Engineering Vol 69 1900-05-04

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E N G I N E E RI N G. 57 1

• YPHO LOClC ON THE apex to the lock, as can be seen in Fig. 5. In this above the suction cylinder commandmg the two THE HOTOPP fiaure the principal dimensions, which are the same volves 0 and c. If the valve v be opened so that

ELBE-TRA VE CANAL. f;r all t he locks, are given : Available length, the air can escape t hrough t he pipe l , ~nd the THE North-East .ea Canal, which joins .. IGel 80 metres (262.5 ft. ) ; width, 17 metres (56 ft ., lever j ust ment ioned be moved, the 'Yater wlll enter

Bay and the Baltic w1th the Elbe at Brunsbuttel, about) ; and depth, 2.5 metres (8ft. 3 in.). The into the cylinder through the plpe 't and the below Hamburg, has not satisfied all the imp~rtant area of the lock chamber is about 15,070 square feet, valve c . the feed comes from t he side of the demands for canal connection between the Balttc and its capacity 135,969 cubic feet; the resen·oir basin upper w~ter. The air outlet is then. closed again and the Elbe. The Old head town of the Hansa, L \ibeck, has twice the area of the lock chamber, and can ill fl t

· d f the lever is turned. The water w now ow ou ·n particular does not profit by the great canal, as supply four-elevenths of the water requue . or R . d d t' · 1~~- 1·8

Q long' wa.y by sea to K. iel Bay around the fillinQ: the lock chamber. At t he gates the w1dth through the pipe , pro~1 e connec Ion lB es-11 Q ..., (3 f · ) Th h d tablished between the cy tinder and the syphon eastern project10n of H olstetn, though not a long of the lock is 12 metres 9 t . 4 m. . e ea s S Th

dl.stance by rail. In the great days of the Hansa, and the walls of the lock piers were each built through the valve and pi.pes , s. ~ er-~ h E b il ' Th b t 1 f linder will begin to empty 1tself, and the a1r will

the Stecknitz Canal was constructed from t e 1 e with its own sheet p mg. e e on ayer o 1. d In d N 1 · k f 400 '11' be sent from the syphon into the cy m er.

to the Trave, on which Liibeck. i.s sitl.;Iate .. ow the lock chamber has a t uc ness o m1 1- h t t (15 75 · ) · 5 ill' t ( l · ) the syphon the water will rise and fall over t e that Liibeck is once more rismg In o Impor - metres . 111. ; wues, . m. Ime res 3 l.n. overflow. As the syphon is narrower at its

ance the old Stecknitz Canal, opened in 1398, has in thickness, are embedded 1n th1s be ton, forming h. h beed closed after al~ost ~xactly five hundred years a netting. Other parts of the concrete have been apex than lower down, the air current w 10 ' of service, to be revived !n the mod~rn Elbe-Trave strengthened by means of 1.6-in. iron bars. The as yet, was from the syphon i~to ~he cylind~r, Canal which is approachmg complet10n. The new gaps left between the heads and the walls have will soon be reversed, and the au will be carr1ed canal 'follows essentially .the .old route. Starting been stopped with flat bars, wound with oakum, down the syphon with the water. As a conse-from Laiienburg, on the JUnctwn of the Elbe and impregnated with tar. quence, the suction cylinder can automatically refil the Delvenau about 30 miles above Hamburg, it Of the two gates of each lock, the one closing itself, the air finding another outlet than formerly makes use of the watercourse.s of the Delvenau and against the upper water, i~ a bear trap dam or li~- through l and v. This refilling will, however, take the Stecknitz, which flow mto the Trave. To I gate, presently to be descn .bed; the other an ord1- place through R, fr01n the side of t he lower wa.te:. anticipate correct.ion, we may say that the Delvena.u nary two-leaf gate. In F1gs . 1 to 5 we see the When it is desired to work another syphon, 1t IS

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appears also to be known under the name of Steck­nitz. The new canal has a length of 67 kilometres 41.6 miles), a bottom width of at least 22 metres

(72 ft. ), and a minimum depth of 2 metres (6 ft. 7 in.). It is not a big canal, therefore, and the means placed at the disposal of the constructors were scanty. But the manner of work­ing the locks is novel and very interesting. F or the facts which we publish, we are indebted in the main to a paper which Professor Hans Arnold, of Hanover, has published in the '' Zeitschrift des Vereins Deutscher Ingenieure," and our thanks are given both to the author and the editor. We further wish to acknowledge our indebtedness to Mr. Hotopp, the designer of the syphon locks, who o?liged us with a descriptive pamphlet compiled by htmself and the engineer.in-chief on the canal, Mr. Rehder.

The canal is fed from Lake Molln, which is about 24ft. above the level of the Elbe, and 40ft. above the level of the Trave. The central reach of the canal, a length of 18. 6 miles, has been ex ea vated to a depth of 2. 5 metres (8! ft. ). The incline down to the level of the Elbe, 5.6 miles in length, has been overcome by two locks, and the incline down to the Trave, 10.5 miles, by five locks. The fall of the locks varies between 5. 6 ft. and 13.3 ft., three of the looks having falls of less than 6 ft. In the ~e of. the other four, the locks have been pro­VIded w1t~ reservoir basins, from which they can be filled durmg the dry season. These reservoir basins have the shape of a sector, the sector turning its

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culverts and the sixteen ports, through which they communicate with the lock chamber; the aggregate sections of the ports represent double the sections of the culverts. But there are no sluices to close or open the culverts, the sluices being replaced by syphons. As shown in the illustrations, the culverts rise near the ends of the lock to form overflows. All these overflows rise to the level of the water in the upper reach. The syphons by which the culverts aro continued, are made of wrought iron, and are lined with cement to lessen the danger from oxidation which the alternating action of water and air might cause. They are rectangular in section, the width at t he t op being 0. 7 that of the culvert, while their lower ends have the full culvert width. The water which passes into or from the lock chamber has to flow through these syphons. This action takes place with the help of the devices illustrated in Fig. 6, page 572. A wrought-iron cylinder has been placed in the lock walls, on the same side as the operator 's cottage, that is on the side opposite t o the reservoir basin, as shown in Fig. 5. The capacity of the suction cylin­der is one-fifth greater than that of the respective syphons which are simultaneously in operation. Its upper edge is on a level with the upper water, and, therefore, with the syphon back, and its size is such that its lower edge always remains above the lower water level.

The suction cylinder communicates with the upper and lower reaches, and also with the syphons and the atmosphere, by pipes and tubes,

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Fl,oat WelL .

necessary only to change the valve v. It would, therefore, appear that filling the suction cylinder from the upper water, in the manner first ex­plained, will o~y be required once for starting the operation . The lever mechanism is, however, also needed, because the cylinder might leak and refuse to operate after a so mew hat long period of rest. The valve V is in the operator's cottage, to which the pipes S and s are taken through a conduit.

This arrangement was first introduced at the Krummesse Lock, which has a fall of 2.75 metres, and having given satisfaction there, was adopted for t he other locks. The suction cylinder has a length of 8. 5 metres and a diameter of 2 metres (28 ft. by 6ft. 7 in.). This gives a. volume of 26 cubic metres (918 cubic feet), while the capacity of the syphon is 11 cubic metres (388 cubic feet). The dia­meters of the pipes are : S, 150 millimetres (6 in.); s, 100 millimetres (4 in.) ; l (air pipe), 50 millimetres (2 in.); 't , pipe communicating with the upper water, 300 millimetres (11.8 in.) ; R, pipe between cylin­der and lower water, 500 millimetres (19. 7 in.). The section of the culverts is 2.4 square metres (28.8 square feet) ; of t he syphon at its apex, 1. 7 square metres (18. 7 square feet). The capa­cit y of t he lock chamber is 3850 cubic metres (136,000 cubic feet); 1400 cubic metres can be taken from the reservoir basin. To empty or fill t he Krummesse Lock requires seven minutes; but ten minutes are required when the reservoir basin is put under requisition.

Some other details have to be described. The gates are moved by means of compressed air and the flow of water through the lock cham her cr~ates the nec.essary ~nergy. The arrangement is illus­trated In the diagram, Fig. 7, which does not refer to. Kru~messe, however , but to one of the locks W:Ith a higher fal~. The principle of this hydraulic au ~o~presso~ IS not new. We illustrated an apphcat10n of It, on ~ ~igantic scale, on page 563, vol. _lxv:, when .descnbmg Mr. C. H. Taylor 's inte­resting Ins_t~llatlons at Magog, Quebec, and at Ains­worth, Bnt1sh Columbia. The latter plant was to be brought to a capacity of 500 horse-power. On the Elbe-Trave Can~llocks no great power is called for. But the adaptati~n of this hydro-pneumatic method of power generation to lock-working has not been attem_pte~ be!ore, so far as we are aware, and the comb1nat10n lB very interesting. A well has been s~nk to a depth of about 20 ft. on the upper pier-head. In t_he concrete a cylindrical bell, 1.9 metres (6 ft. 3 In.) has been fixed ; this vessel ia

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E N G I N E E R I N G.

that th~ fl~w through f can re-start ; the water will then rise In the ascending leg of h. Before the lock chamber is .emptied, this valve again is closed. The syphon h will then automatically beoin to act a~a~. I~ this way a fresh supply of c~mpressed ai: IS o~ta1ned by merely turning a cock twice ; the 2-m. p1pes o and u take the air to the operator's cottage. The ~ell has a capacity of 4.5 cubic metres (159 cubtc feet); about 3 cubic metres of compreseed air are required for operating the lock gate.

The bear trap dam or lid gate, Fig. 7, which closes the. lock cham~er on the high-water side, forms an uon box whiCh turns about its horizontal axis Being a little heavier than water, is lies norman; on t he floor of the lock chamber. To move t he g,.te, air is admitted into one of the gate com­partments, the second one reckoned from the top of the gate, marked. k in Fig._ 7. The pipe o conveys compressed a1r to an 1ron trough in the floor of the lock-gate chamber. The gate

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Compressed air is also used for operating the lower gate. The arrangements made for this pur­pose are illustrated in Figs. 5 and 8. To a chain are f~s~ened an iron bell T, which we will call the dtv~ng bell, and a counterweight G. The bell m?ves In a well, the position of which is shown in F1g. 5 ; the counterweight is suspended in the gate r~cess. The parts are duplicated on the opposite s1de of the lock for the other leaf of the gate. The well has a depth of 4. 5 metres, and is always full of water. T~e bell has a diameter of 1.6 metres (about 4ft.), a he1ghtof 1 metre, and weighs 665kilogrammes (1466lb.) more t han the counterweight. '¥hen com­pressed. air is introduced into the bell through the flextbl~ tube 11,, the bell beoins to rise · when q u~te full of air, its buoyancy is twice its' excess we.Ight, s? that the acting force is 665 kilogrammes. With th1~ pull the load acts on its own gate leaf, closmg the gate when the bell is risina. The chain is fixed direct to the rod. At the Krummesse Lock, where these novel arranae-o

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called the compressed-air bell. The pipef through which the water from the upper reach falls into t he bell, is double funnel-shaped; at its bend it has only 0.4: of the maximum width, 13.5 square feet, at its lower extremity, which is about 10 ft. below upper water level, and 16 in. above the floor of the well. The syphon pipe h rises from a slightly higher level, 20 in. above the floor of the well, extends its horizontal arms just up to the level of the upper water, and then down into the lower water. In the top of this syphon an air pipe n~t, 1. 6 in. in width, has been fixed, which leads to the valve v in the operator's cot­tage. The overflow pipe f is also provided at its bend with an open air pipe x , about f in. in dia­meter. When water falls into the well through the pipe f, a strong suction will be set up at the bend where the section of the pipe is dimi­nished, and air will be drawn in through x and col­lect above the water in the upper part of the bell, pressing the water through h over into the chamber. This will continue until the water level in the bell has sunk below the mouth of h. The syphon h will then cease to act, and the air will not further be compressed in the bell. The greatest water pressure obtainable in this well is that due to 9. head of 16 ft. 5 in. If the valve is now opened in the pipe m, the air will find an escape from h, so

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is provided with open ports, which guide the compressed air into the compartment k, where it replaces the water. The gate begins to rise; finally it leans against the pier blocks in the slightly inclined position indicated in Fig. 7. This rise of the gate is accomplished within one minute. The pressure of the water above keeps the gate in this position, while the lock chamber is being emptied, although the buoyancy of the gate would soon become insufficient to prevent it sinking. There is a bent air pipe i, 1 in. in diameter, leading to the back of the gate, through which the enclosed air can escape, as soon as the water in the lock chamber has sunk low enough. The compartment k, th erefore, becomes refilled with water from the upper water side, and the gate will be ready to fall again and to reopen t he lock. This cannot take place, of course, before the lock chamber has been refilled by a renewed action of the suction cylinder and syphons. The dimensions of the compartment h are 12 by 0.6 by 0.3 metre (39ft. by 23.6 in. by 11.8 in .), corresponding to a capacity of 2 cubic metres (70.6 cubic feet). The mouth of the air supply pipe o is 3.3 metres (130 in. ) under water level. One cubic metre of compressed air, under a pressure of 4. 5 metres, suffices to move the gate.

ments were first t ried, a. rack and toothed gear was employed; simpler mechanisms have been adopted, however, for the other six locks. When the gate is shut, no further force is needed to keep it closed. The compressed air may, therefore, at once be discharged. The bell will then be ready to sink again, and when the lock chamber has been emptied, and the water pressure taken off the gate, the bell will automatically descend n.nd again open the gate. This movement also occu­pies one minute, and about 2 cubic metres (70ft. ) of air are required to effect it.

To summarise the operations, we will assume that a ship approaches from the lower reach. The lower gate is closed by manipulating the air pipe u; the lock chamber is filled with the help of the syphon on the upper water side ; these two operations take from one to seven minutes. During t his time the valve in the pipe m is opened, allow­ing the air to escape from the syphon pipe h of the compressor (Fig. 7). The upper gate will now open automatically, and the vessel pass out of tho lock ; valve m has now to be closed and valve u to be opened, so that the diving bell is released. \Vhen the vessel comes in the other direction, the upper gate-the bear trap-has first to be closed, which is done with the help of t.he air pipe o. The lock chamber is then emptied by means of

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the syphons on the lower water side. During this operation, the syp~on h of the c~mpres~or starts by itself, ge~erat~g compre~sed au·, whllst th compressed atr wluch has lifted t he ga~e es~pes through the pipe i . . The difference m water level having been equal~s~d, the lower gate 0 ens automatically as the dlVmg bell 'Yas n?t b~oyed up all this ~ime. The ~vh?le ~ocki~g will be accomplished, in eit~er ca~e, w1thin n1ne minutes, and as all that is r equired IS to turn a few v~l ves,

laced in the operator's cottage, the lock machinery aoes not need more than on~ att~ndant. ~he syphon locks are therefore economiCal In operation.

The construction of the Krummesse Lock firat finished has cost a little less than 20, OOOl. The Hotopp syphon appliances them~elv.es, apart from culverts, &c., which would be Indtspensable for any system of working, have been constr~cted at the expense of ab~ut 1200l., ~ot reckon1ng the reservoir basin, wh1c~ would brmg the cost up to 165m. Hand mecha.msms would, no doubt, have been cheaper, but the lock-~eeper could not have managed them without assistance, and t he . con­structors were desired to reduce the ~xpend1ture for the lock sen·ice as much as posstble. The manner in which Mr. Hotopp has solved t he pro­blem is certainly ver~ ingenious, and tl~e success of his mechanism wtll be watched w1th great interest.

MODERN FIELD ARTILLERY. ( Co·ntinued from page 542 )

TnE ScHNEIDER-CANET SYSTEM.

75-kiillimetre (2.952-In.) (}wn,. Long Type, on (Jan·iage ~with lndepen~ent Axle (F~gs. 97 and 98).­The following are particulars of this gun :

Weight of gun. ... ... 360 kilogs. ( 793lb.) ca.rrtage .. . . . . 540 , ( 1190 , )

" projectile .. . 5. 2 , ( 11 ~ , ) Mu~~le velocity ... ... 550 m. (1804 fu.) Stnking t;nergyof projectile 80 t.-m. (266 foot. tons).

The carria.ae consists of two steel-plate brackets joined together by riveted pl~tes fo!ming transoms; 1t is supported by the trail w h10h rests on t he ground and on an elastic arrangement which connects it with the axle. This arrangement consists of two

E N G I N E E R I N G.

by a handwheel. Acc?rding to the direct~on in which the handwheel IS turned, the nut nses or descends, and gives the required elevation to the gun.

As the trail is not fitted with a spade, the car­riage recoils at each round over a length. wh.ich depends chiefly upon the energy of the proJectile. The recoil, however, and subsequently the work the gunners had to do to run out the gun afresh, was less than that required for the types of guns and rigid carriages already described.

76-lVIillimet·re (2. 962-Jn .) Gun, Long Type, on Cwrn'age with Spade in. a Li·ne u:ith the .Axle (Fig. 99). The following are particulars :

Weight of gun . . . . . . 360 kilogs. (793 lb. , oa.rriage complete 750 , (1256 , , projectile ... 5.5 , (11~ "

Muz;r.le velocity ... ... 550 m. (1804 ft.) Energy of projectile .. . 80 t.-m. (266 foot-tone).

Several examples of this. typ~ were experimen~ed upon successively at the Vllledieu and Hoc provmg grounds. It was the first of a comparatively large series. The carriage consists of two riveted brackets stayed together by top and bottom trail­plates ; at the lower front part are two supports for an axle, on which the spade is jointed. The latter is formed of two vertical arms, the blade being at their lower part and adapted to penetrate the ground. 'rhe top part of this anchor is fitted with an inclined plate which throws back the ear th when firing takes place in loose ground. The spade is secured to the trail by jointed t ie-rods, a set of Belleville springs being placed between the ends of the rods and the vertical arm, to deaden the sudden reactions which might arise during firing. When it is desired to shift the gun, the spade is lifted near the bottom trail-plate. When a round is fired, the spade is driven in the ground and forms a bearing-point to deaden the force of recoil. The conditions in which this device works vary, how­ever, according to the nature of the ground, and when the latter is not suitable, the gun and car­riage are lifted up and may be thrown forward. But when the ground is favourable, the recoil is much less than with the types firin g with no recoil checks ; on the other hand, the gun often deviates largely, the carriage platform not remaining still.

FIG. 97. 75·MILLIMETRE GUN AND CARRIAGE WITH INDEPENDENT AXLE.

rods linked to the brackets, the elastic system being in two parts, one jointed on a carriage-bar, formed of a hollow cylinder made to turn round an axle parallel with the carriage-axle; the second con­sisting of a piston which travels in the cylinder, the piston-rod end being so arranged that it can turn freely round the carriage-axle. A set of Belleville springs is placed on the piston-rod, between the piston and the front end of the cylinder. When the gun is fired, the springs are compressed and the jointed system comes into action. Part of the force developed during firing is thus absorbed by the springs ; this eases the various parts of the carriage, so that they can be made lighter in conse­quence. When the action has attained its height the carriage and the gun resume their respective positions by the relaxing of the springs.

The mechanism for elevating the gun consists ~ainly of two jointed rods; one is jointed on the Jacket at the breech end of the gun, and the other on a carriage bar. Upon this second rod is fitted a nut which can be displaced over a screw worked

This system nevertheless marked a decided im­provement on the preceding ones ; it was less fatiguing to work, and the firing speed was a little quicker. 76-Millime~re (2.962-In) Gwn, Rcat~>y Type, on

Ca,rriage with ll1·ont Spade (Fig. 100). - The fol­lowing are particulars of this gun :

Weight of gun .. . . .. 360 kiloga. ( 793 lb.) , carriage .. . 580 , ( 1278 , ) , projectile ... 5.2 , ( 11! " )

Muzzle velocity .. . ... 550 m. (1804 ft.) Energy of projectile .. . 80 t. -m. (26G foCJt-tons).

In order to improve the working conditions of the preceding type, a. mounting with front spade was made and tested. The joint of the vertical arm was placed at the height of the muzzle by 1neans of two supports fixed at the rear part of the brackets and joined to the axle by stays. To pre­vent the trail from cutting into the ground, ae fre­quently happened with the preceding type, a plate having a wide bearing surface was bolted to the lower end of the trail. With this arrangement the

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573 :

gun and carriage lifted less than w h.en the spade was placed direct under the axle, ~ut It entered. the ground to a less depth: The c~rr1~ge was ~~dlfied several times with a view of bnngmg th~ JOint of the spade nearer the vertical of th~ ,ca.n·~age ax.le, but without removing the same d1fficul~1es, w~lCh were, a rising of the whole system, or 1nsuffi~1~nt penetration of the spade, according as the JOint was more or less near the plane of the axle.

76-Millirnetre (2. 962-In.) (}u.n, Long ~Pype, .on Carrictge wUh I ndepe11dent A xle, and Spade tn Line with the Axle (Figs. 101, 102, and 103).-The fol­lowing are some parti ~ulars :

Weighbofgun ... . .. 360kilogs. (793lb.) Weight of carriage, in one (

1388 )

case . .. .. . .. . .. . 630 , , Weight of carriage, in

another case ... . .. 640 , (1410 , ) Weight of projectile ... 5.2 , (11! , ) Muzzle velocity ... ... 550 m. (1804 ft.) Energy of projectile... ... 80 b.-m. (266 foot-tons).

Another type was then tested, which combined the use of a spade placed directly under the axle, but the latter was independent. Two mountings of this kind, with slight vari~tions, were tested. ~he system of elastic connectiOn between the carriage and the axle, remained as in those already de. scribed.

These patterns did not show any marked im­provements on the preceding ones, as r egards the resul ts obtained separately with a carriage on independent axle and with a carriage, the spade of which is directly beneath the axle. The spade penetrated even less than with the preceding types, and acted very ineffectually when firing took place on hard ground. .

76-Millimetre (2. 962-In .) Long Type, on CaT'?·tage with Inclined Slide and Spade beneath th e Axle. - The following are particulars of this gun :

Weight of gun ... ... 360 kilogs. ( 793lb.) " carriage ... .. . 660 , .(1454 , ) " projectile ... 5.2 ., (11 ~ ,. )

Muzzle velocity ... ... 550 m. (1804 ft.) Energy of projectile ... 80 t.-m. (266 foot-tons).

The gun-carriage in this case consists of the brackets with a spade beneath the axle, the slide, and the hydraulic recoil cylinder. The brackets and spade are similar to those already described ; a horizontal plate prevents the trail from ploughing up the ground . On the carriage head plate is placed a support which forms t he slides, and is provided with the hydraulic recoil cylinder. The support is mounted on a pivot, and ca.n be inclined under various angles. A cast-steel cradle in one piece, with two vertical supports, the top of which forms the trunnion rests, is made to slide on the gun-metal guides, and is held by lateral clamps. In the central part of the cradle is a lug to which is fixed the recoil piston-rod. The recoil cylinder contains a piston, the rod of which is grooved out along its centre, for receiving a regulating counter·rod. A number of ports establish communication between the front and the rear of the cylinder. The gun runs out by gravity alone, the slide resuming its former position gradually, and without any shocks. Owing to the spade being placed beneath the car­riage axle, the rising of the gun and carriage was still too great. The hydraulic cylinder acted well, but t.he general working would have been much more satisfactory had the travel of the piston been greater.

80-Mill,imetre (3.149-In.) G·wn, on Ca·r·ticrge uith T1·ail-Spade:

Weigh b of gun . . . . . . 425 kilogs. ( 936 lb.) , carriage .. . .. . 495 " (1091 " ) , projectile .. . 5. 6 , ( 12 , )

Muzzle velocity ... .. . 490 m. {1608 ft.) Striking energy of projectile 68.5 b. -m. (228 foot-tons).

The carriage is the same as that first described­for the SO-millimetre gun-but the trail is fitted with an elastic spade.

Schneide?·-Oanet Gtvns on Cat~Tiages with Com­p?·essible T1·ail. - One of the deductions from the first series of theoretical r esearches and practical experiments, an abstract of which has been given in the preceding paragraphs, was that among all the types of mountings tested, not one had the required stability which is essential to modern quick-firing field artillery. Though in the long course of successive experiments, results were ob­tained which suggested alterations and improve­ments, so that the series was essentially proares­sive, and though no definitely satisfactory type was elaborated, the experience gained served as a. basis for a new programme for improving ordinary

574 E N G I N E E RI N G.

gun-carriages still in service, as well as to a com­plete revolution in field armament . Each of the types we have described, when it was fired, r ecoiled, lifted, and deviated, of ten to a great exten t , b ehaving, in fact, in quite an unsatisfactory fashion. In some examples, t hat part which was the main bearing point of the system, was liable to shift

progressively. This series of the Schneider-Ca.net exp eriments had practical results, and various examples of fi eld gun moun tings with elast ic trail were manufactured, one impor tant order being executed for Uruguay.

that the system originated and was first tested in Germany ; it will be of interest therefore to put forward the chneider -Canct claims in this matter.

I t was in F rance and in conj unction with the Schneider- Canet type of artillery, that this special kind of t rail was first designed and manufactured; it was afterwards improved by Messrs. Schneider

The compressible t rail system is one likely to have so wide and impor tant an application that a.

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FIG. 99. 75-MILLIMETRE G cN AND CARRIAGE WITH ANCHOR-PLATE BENEATH Ax.LE.

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- -·-·-- -·- J :---- -- -.I_

Fro . 104. 75 -MII.LIMETRE GuN WITH ELASTI C 'l'ttAIL AND INDEPENDENT A xLE.

under fire to a. large extent. ; this often disorganised the trials in a. very short tlme, and ca~sed ~he gun t o trip up suddenly in the course of rap1d ~mg.

These conaiderat ions led Messrs. Schnel~er and Co., during the fir&t series of tests~ to des1~ and

Fws.

Fig.101.

•

•

Ftg.102.

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Pig.103. - -r-.f- - ~~~~~;-::._ +t-=·-~r-.::=-~-=·-_:-::.:·-=-=-..:.:=.J

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------------------------

101 TO 103. 75 -MILLIMETRE G u N AND CARRI AGE WITH I NDEPENDENT A XLE AND ANCHOR-P LATE.

Fr{J. 105. .---...

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FIG. 105. 7 5· MILLThiETRE GuN WITH ELASTIC T RAIL AND GAS BRAKE.

--. / I -... / "'-...

F lfJ.106.

F iv. 106. 75-MILLl METRE GcN WITH T RAIL BRAKE.

H YDRO-P NEUMATIC

experimen t with a ~ew type of ca.rrlages ha.vmg an elastic t rail. I t will be seen hereaf~er t hat the few words should be given in r eference to a. co~­extent to which one part of the. trail .telescope~ t rovers of recent date as to the origin of . this within tho other , was progressively l~cre~ed d system~ in the controversy referred to it is clalmcd various details were, also, of course, lmprove . ,

and Co., until they felt justi fied in executing an impor tant order for ruguay, as a.bo~e stated. F ive complete batter ies of guns on t lu s system

MAr 4 Igoo.] EN G I N E E RI N G. 575

SCH I EIDER-CA ET SYSTE~1 OF J\'[0 NTIN G FIELD ARTILLERY.

•

Fro. 107. 75-MI LLil\[ETRE GoN WITH H YDR O· P NEUMA'l'IO TRAIL BRAKE.

FIG. 109. 75-MILLIMETRE Gc~ WITH ELASTIC T RAIL :FoR THE URUGUAY GovERNMENT.

Fxo. 112. 3-I~ . G v N wiTli T ELESC<"' P IC R.eco1L BRAKE.

were put in regular service in that count ry wi th complete success, after exhaustive trials had been carried out at the H oc proving ground, as well as severe cross-country and rolling tests made at Monte Video by a ruguayan regiment of artillery. I t was, moreover, during the experiments carried out in France with this system, that, so it appears, a carriage with a double elastic trail W 3S tested in Germany. It is worthy of comment, that consider­ing the rigid rule in Germany to simplify field artillery and its mountings, that a system should have been designed which embodied not one, but two distinct devices for hydraulic recoil. As a matter of history, the French patent was first ap­plied for in France, then in Germany and the Berlin Patentamt granted a patent, as is customary, after preliminary researches into the question of prio­rity. Everyone knows the care taken by the German P atent Department before a. decision is arrived at, and their having granted these patents appears to settle the discussion in favour of the French manufacturer. With these few wo1.qs of introduction, we may proceed to consider the second series of experiments.

75- MiUimet?·e (2.952 ·In .) Short {rlt,rr,, on Ca r­riage u:ith Elastic T1·ail and I ndepende1tt A xle (Fig. 104). - The following are particulars of the gun:

\V eight of gun . ... ... 260 kilogs. (573 lb.) , ca.rrtage .. . .. . 410 , (903 ,, ) ., projectile ... 4.6 , ( 10 ., )

Muzzle velocity ... ... 480 m. (1579 ft.) Energy of projectile . .. 51 t.-m. (180 foot-tons).

The first carriage of this type was made with a telescopic trail which con tained an elastic device, consisting of india-rubber rings placed one over the other; these were compressed when firing took place, returning their energy immediately after­wards. The carriage may be considered to be formed of three main parts ; the carriage proper carrying the gun ; the spade connected to the cn.rriage ; the independent axle and the wheels.

The carriage consists of two steel plates and brackets which take the gun trunnions; at the lower part of the brackets, and in front , are soleplates on which slides a saddle-plate carried on the axle. The brackets are joined together in the rear and end by cylindrical connections formed of two ockcts of different diameters made to slide one

within the other. Thes~ two cylinders are con. nected by a set of india-rubber rings, which, when t he gun is fired, are compressed, and cause the trail for the moment to decrease in length. The india-rubber rings then relax and run out the gun again. The bot tom of the lower cylinder is made with a circular groove, the cent re of which is practically on a vertical line drawn from the centre point of the axle. The trail-spade consists of a. steel blade that bears against a horizontal t rail-plate. The top surface of the latter is made with a ridge that fi ts in the circular groove in the lower cylinder, in which it can slide freely, the slide being limited by catches at both ends. 'Vith this axrangement, when the spade has been

•

placed in a hollow, or when it has penetrated the ground automatically after firing the first round t~e carriage can be shifted over small angles to th~ right or to the left ; the lateral training of the gun ?an thus be co~rected, when only a slight shift ing Is neces~ary, without extracting the spade.

In thlS. first type, the a.xle was independent of the carn~ge, the foll~wing arrangement being a~opted: It was fitted with two saddle-plates oppo­site the ~oleplates of the brackets ; these plates were provided at one end with india-rubber buffers the other end bearing against angles ri vetted to th~ brackets. When the gun was fired the brackets by recoiling, drew back the axle a~d the wheels' by pressing down the intermediate buffers. At th~ same time, the trail cylinders telescoped and com­pressed the set of india-rubber rings. The trail spade penetrated the ground more or less deeply accordtng to the hardness of the soil · it formed the required bearing point to limit ~ecoil and cause.d the ca~ria:ge to ru~ out again by the relaxtng of ~he Indta-rubber rings. In some experi­men~ the rmgs were replaced by metallic springs. It w~ll be ~ee_n that ~l~ost t he whole of the system rec01led wit~m the hmit allowed by the compression of the elast1c column, the 1iis-viva of recoil beina greatly reduced.

0

The results obtained with the first trials of this type were very interesting ; the carriage still re?oiled. and ros~ when fired, but to a lesser degree ; th1s ev1l was, In fact, so much reduced that it appeared likely, br_improving the various parts, a much greater stability would be obtained than with a~y of the preceding systems. Numerous other tr1als were made, among others, some with the gas check at the muzzle, already described. With this appliance, recoil was lessened; but its dis­advantages as regards inconvenience t o the gunners still existed, and it was finally abandoned.

The type which was tried with the gas check at the muzzle, is shown in Fig. 105; from this it will be seen that the trail had been lengthened.

75-Millimetre (2. 952-In.) Gnn, Long T ype, on Carriage with Compre'3sible and H ydro-Pnenmatic R ecoiling Trail (Figs. 106 and 107).-The following are particulars of the gun :

Weight of gun . . . . . . . 360 kilogs. (703 lb.) , carnage .. . ... 770 , (1607 , , projectile ... 5.2 , (11' , )

Muzzle velocity ... ... 590 m. (1936 ft. ) Energy of projectile . .. 92 t. -m. (306 foot-tons).

The trials which had been made with the first types of carriages with elastic trail proved the new system to be one of great promise ; they also showed that by increasing the length of action of the two parts of the trail, the stability of the system was also increased. I t may be mentioned here that all the trials we refer to were carried out in the proving grounds belonging to Messrs. chneider and Co., with the help of the most perfect measur­ing and recording instruments, such as crusher gauges, velocimeters, chronographs, &c., with which every action caused by firing was duly analysed ; all parts that were found to work unsatisfactorily were, of course, modified immediately.

These trials showed that the working conditions of the carriage would be further improved if the elastic parts first employed, and which acted simply as buffers, were replaced by a hydraulic brake device, which would constantly offer a resistance directly proportioned to the energy of recoil. If this were obtained, it would check the rising of the gun, and prevent its deviation. A first example of this type of carriage was therefore experimented upon. It consisted mainly of the carriage proper, t he trail­spade, and the hydro-pneumatic recoil trail.

The carriage was formed of two principal parts; one, of cast steel, was a cylindrical t ube carrying in front two vertical brackets in which the gun trunnions are fitted. The tube was closed in front by a cover , in the centre of which was a passage through which compressed air was introduced in the recuperator ; this was closed by a valve. The carriage formed, with the gun, the axle and the wheels, the movable part which recoiled and ran out again. The second part was the trail, which remained fixed during firing; it consisted of a forged-steel tube, which contained the hydro-pneu­matic arrangement for checking recoil. I t was provided in front with an outside gun-metal lining, which facilitated the sliding of the two parts during recoil and return, t he sliding action being, more­over, controlled by lateral guides. A gland, through which ran the tube for t he introduction of compressed air, closed the t rail at its front part;

E N G I N E E R I N G.

it was closed at the rear by a cover in the centre o.f which was fixed the central cdunter-rod. A rmg, t o which was fitted the trail-lifting lever, was also screwed on t~e l?wer end. The spade was att~ched to the trail with a groove and rib, as de­scrlb~d for the preceding type, this arrangement enablmg the gun to be trained over small lateral angle~ . The s.pade was of steel, and bore against a honzontal trail-plate ; it could be easily removed when, for any reason, it was desired to fire with free recoil, as in the old rigid trail system. To obtain this, it sufficed t o fix the two tubes one on the other by placing a ring in a groove on the r~ar tube; the movable tube butted against the nog, and the trail remained rigid.

The hydraulic recoil cylinder and the recupera­tor were contained in the lower fixed tube. The recoil cylinder was on the Schneider-Canet system

Fig. IOB .

•

In some ca~es the gun rest.ed in a small carriage made to pi vo~ on the . carriage proper, a special ha~d ~heel be~ng provtded for rectifying lateral traH~mg. Th1s arrangement also gave satisfaction, and It was chosen by the Uruguayan Government for the ordnance they ordered, and which was manu­factured at the Havre works.

75-Milli?netre (2. 952-In.) Gun on Carriage 1t:ith Compressible '!rail Adopted by the Untuuay Government (Ftgs. 108 and 109). - The following are part-iculars of this gun :

Weight of gun . ... ... 260 kilogs. ( 573 lb.) , carrtage .. . .. . 585 , (1289 , )

M ,,

1 projectile ... 5 , ( 11 , )

uzz e velocity .. . ... 470 m. (15t2 ft.) E nergy of projectile ... 56 t. -m. (186 foot. tons).

: This . type contained, besides t hose parts men­honed ID the preceding descrip~ion, a small carriage

•

FIG. 108. 75-MILLtMETRE GuN WITH ELASTIC TRAlL FOR THE URUGUAY GovERNMENT.

·-·----

F,;g.no. 1

•

SJSC V

Fxo. 110. 3-IN. GuN WITH TELESCOPIC RECOIL BRAKE.

Fi<J . lll.

'

.......-- ·-- ·-- --•

•

(SJao. vJ

•

FIG. 111. SECTION OF TELESCOPIC RECOIL BRAKJt

with central counter-rod. The liquid when dis­pla?ed, acted on an airtight movable diaphragm, whiCh separated the liquid from the air contained in the top part, and the diaphragm compressed the air in front of it. The air by expanding when recoil ceased, caused the liquid t o flow back, and the gun ran out again automatically.

The results obtained with this type were very satisfactory as regards stability. The gun which recoiled after each round with t he front t ube of the t rail, returned alnwst completely to the position it occupied beforo firing the preceding round; and by regulating the ports in the recoil cylinder and the air pressure in t he recuperator, the rising of the whole system was practically done away with. The spade held well, and generally penetrated com­pletely at the first round without loosening the ground. The device for slightly rectifying the lateral training acted well, even when covered with earth and mud.

Several specimens of this type and of various calibres were manufactured and test ed in succession.

movable on the gun-carriage proper, and whit h serves for rectifying lateral training. This arrange· ment necessitates a second hand wheel for the late1al training. The small carriage consists of a cast-steel circular platform in one piece with two vertical brackets, the gun trunnions fitting in the top part of the latter . The platform is free to turu rvund a central bearing which forms a vertical pivot ; it rests on two circular guides fitted with gun-metal slide­plates that form part of the gun-carriage proper, clamps in front and in the rear preventing the shifting of the system when the gun is fired. The left-hand bracket is continued at the rear as a sup­port for the gun-training mechanism. The required elevation is obtained by a screw, the head of which bears constantly against the breech end of the gun. It travels in a nut carried on the cxt~nsion of the small carriage, the rotation of the nut being pro­duced by an endless screw worked by the hand­wheel. The gun is trained laterally by displacing the small carriage by means of a screw, tlie nut of which is jointed on the shoe-plate of the gun. carriage

MAY 4' 1900.]

proper · the rear end of the screw rests on a second jointed' support mounted on the extension of the small carriage. The system is W?rked by a hand­wheel. The wheels are of wood with steel centres ; the brake used when the ordnance is wheeled from one place to another, consists of a circulAr band that surrounds the nave ; it is not used during firing. . . . .

This descriptiOn completes the sect10n dea.lmg with elastic trail carriages. This system has been carried by Messrs. Schneider and Co. to a high degree of perfection ; it allows the firing of 10 and 12 rounds per minute by gunners having no special training. This speed is in excess of what can be obtained with rigid tail carriages, provided with elastic devices for deadening the force of recoil. As has been previously stated, the system works smoothly and the spade scarcely recoils, when the gun has once started regular firing. The rising of the carriage is negligeable. This type is, there­fore, suitable to replace the older ones, over which it constitutes a. marked improvement.

During firing, however, the gunners are obliged to stand in the rear, or outside the wheels, owing to the backward and forward motion of the latter. The consequence of this is that the guns cannot be fired with the rapidity now demanded by modern conditions without undue fatigue to the gunners. This has led Messrs. Schneider and Co. to design and experiment with another class of gun-car­riage for extra rapid firing, in which the wheels remain in place, and by which 20 or even 25 aimed rounds per minute can be fired, without fat igue for the gunners.

The following section deals with this type, and especially with the 1898 pattern, which it is claimed fulfils to a high degree all the conditions embodied in the present programmes of the French Ordnance Committees, whose main study is now the transformation of field artillery.

3-In. Gun, Long T ype, on Oat'riage with Tele­scoping Recoil Otjlinde1· (Figs. 110, 111, and 112). The following are particulars of this gun :

. . . 430 kilogs. (948 lb.

.. . 870 , (1917 ,

... 6.2 " (13i ,

.. . 610 m. (2001 ft.)

. .. 117 t. m. (390 foot-tons).

Weight of gun • , carriage ...

,, projectile Muzzle velocity ... Energy of projectile

...

The carriage may be divided, for purposes of description, into two main parts ; the carriage support and the carriage proper. The carriage support consists of t wo fixed plate brackets ; it is joined by a circular rib and slide to a trail-spade, on which it can be displaced to the right or to the left, for regulating the lateral training. The gun rests in two collars placed one near the reinforce and the other in front of the breechblock ; the collars are in one piece with the slide. The latter, during recoil and return, travels in a forged -steel cradle fitted with the recoil cylinder ; the cradle rests partly on the brackets through its trunnions and partly on the head of the elevating screw, to which it is jointed.

The telescoping cylinder (Fig. 111) has been de­signed specially with a view to meet a long recoil of the ~un without its being necessary to lengthen the carriage excessively. An outside cylinder forms part of the cradle and remains fixed when the gun recoils ; it is fitted in front and in the rear with a gland and two flanges, in which are screwed the tubes that contain the recuperator springs ; these tub~s are supported near the middle of their length. A Pl:Bton travels in the outside cylinder and forms an mtermediate recoil cy tinder with relation to the piston proper, which is joined to the gun. These concentric cylinders and the piston proper telescope one in the other during recoil and return. A head-piece is screwed on the rear end of the int~rmediate cylinder ; it is fitted with two flanges, agamst one of which bear the right-hand re­cuperator springs, the other supports the left­h~nd recup.erator-rod: The gland plug of the recoil plStofl:-rod I~ screwed m the centre of the head-piece; t~e .Ptston IS made with a port which allows the hqm.d to flow from one side to the other, a reglet caus~ng the opening of the vent to vary as may be reqmred. The piston-rod is joined direct to the ~reach end of the gun ; a neck fitted with a valve Is placed in. the ~entre of the system, and serves to fill the ~ecoil ?Yhnder. The shoulder-piece to which t~e recoil-rod IS fixed, is fitted on the right-hand side With ~ arm on which the rod of the right-hand recuperator i~ bolted. The recuperators are formed of seta of sprmgs placed inside the cy lingrical tubes

E N G I N E E R I N G.

fixed to the cradle; these springs are divided by diaphragms, and are placed on a central rod.

The required elevation is obtained by means of a screw jointed on the cradle and which turns in a nut, the latter being worked by two bevel wheels - one keyed on the nut, the other on a hollow horizontal shaft set in motion by a handwheel driven by the gunner. Lateral training is obtained by displacing the trail. To obtain this, the spade is provided with a rack worked from a pinion keyed on the same shaft with a pitched wheel driven by a plate-chain. The latter is worked by a pinion keyed on a shaft placed concentric with the hollow shaft for elevating the gun. The two hand­wheels for elevating the gun and for lateral train­ing are therefore on the same centre.

(To be continued.) •

THE INSTITUTION OF MECHANICAL ENGINEERS.

ON Thursday evening of last week, April 26, an ordinary general meeting of the Institution of Mechanical Engineers was held at the Institution House, Mr. J. Hartley Wicksteed, Vice-President, occupying the chair in the absence of the President.

RoAn LocoMOTION. The only business on the agenda. was the reading

of a paper by Professor H. S. H ele.Shaw, of Liver­pool, on the subject of " Road Locomotion. " We commence to print this paper in full in our present issue, and may therefore at once proceed to the discussion.

Mr. A. J . F. Aspinall, in response to an invi­tation from the chairman, referred to the statement made in Appendix II. of Mr. Hele-Shaw's paper to the effect that in the case of a steam lorry, made by the Thornycroft Steam Wagon Company for the Lancashire and Yorkshire Railway Company, the daily consumption of coke was 259. 7lb., and of water 191.7 gallons were the average daily consumption, giving an evaporation of 7.38 lb. of water per pound of coke. The coke consumed had been 23.4 lb. per hour, or 22.05 lb. per mile; whilst the water evaporated had been 17.14 gallonR per hour, or 16.15 gallons per mile. How much had to be spent for maintenance and repair could not be stated. The wagon was one of the Thornycroft type, and they were determined to give it a thorough trial in carrying goods to and from their depots, after persuading Mr. Thornycroft to part with the vehicle, although he had no small diffi­culty in doing so. The experience gained led him to the conclusion that the results were fairly satis­factory ; but he could not say that the mechanical traction was better and cheaper than horse traction in all positions. It was, however, true that they had found nothing to complain about'; but the question of cost was not yet Rettled. They had heard papers read before that energetic body the Liverpool Self­Propelled Traffic Association, in which it was attempted to be proved that the new method was cheaper than the old-fashioned way of moving goods on the railway. He would like to know how the 10-mile rate was arrived at, seeing that in this country such a thing does not exist. There were plenty of references t o cost of carriage, but these only referred to a certain class of goods. In regard to the passenger traffic he had recently been staying in a part of France where the motor car may be said to be rampant. It was impossible to take a walk in peace, for one had constantly to get into the ditch to let the motor cars tear past. He sincerely hoped that in this country motor cars would not be allowed to 0'0 at the excessive speeds that were sometimes ~een. Such a course would bring the whole thing into disrepute, and choke a new and promising industry.

Mr. J. Brown, of Belfast, the inventor of the '' Viagraph," an instrument to which reference hacl been made in the paper, said that he had made the invention for philanthropic purposes, and not for the purpose of putting it on the market. It had been said how much better the roads were in England than in Ireland, and his object had been to reduce the statement to more precise terms. The arrangement consisted mainly of a straight-edge placed on the road surface, and in this way the raised parts and the depressions could be measured and a record taken, by mellns of a serrated wheel which followed the unevenness on the road and marked them on a paper. There was an addition by which the sum of. the irreg~laritie~ were automatically ascer­tained for a gi van distance. The instrument had not come into general use, but the cycle clubs had

577 taken the matter up, and h~ ~oped they wo~ld be able to impress the authont1es. The quest10n of surface was of importance, as it was useless to com­pare the power needed to propel two vehicles r e­spectively if one were on a smooth road and the other on a rough one. In a leaf spring used in the Thornycroft wheel there should not be friction between the plates, otherwise there would be a loss of energy. ln this respect it differed from a ~p~ng used for ordinary pur~oses, where the fr10t10n acted much as on the principle of the dashpot. In spiral springs there was the difficulty of likelihood of breaking at the point of attachment.

Mr. J. I. Thornycroft, who rose in response to an invitation from the chair, said that the author had left very little to say. The paper was of uniform merit, but he could hardly concur in the statement as to the life of wheels. It was, how­ever, most desirable, if it were possible, to employ a pneumatic tyre to "absorb an obstacle" (to use the author's expression), as in that case the difficulty of heavy roads would be largely overcome. How­ever, this might be, he thought it was most desir­able in the meanwhile to have a better road. He had been making further experiments of late with wheels, and reached better results. Fore wheels built up with plenty of wood would last well under ordinary conditions. If they were run at extreme speeds, it would be necessary to have something different from ordinary wheels, but the answer to this was that they should not be driven at too high speeds. The driving wheels would last a reasonable time, but the first thing to go was the tyre, and they could not increase the weight to any great extent when travelling on the road. In regard to resistance, that increased enormously with a bad road, and he had found sand worse than really formidable obstacles, it acting almost like an adhesive substance. Speaking on the question of cost, Mr. Thornycroft stated that it would not be so great as to detract from the value of steam-driven vehicles for moving goods on common roads. These motor wagons would take loads over hills not prac­ticable with horses, and which it would not be thought of negot iating by the railway.

Mr. Wicksteed at this point said that the dis­cussion would be adjourned until the June meeting, when the 1000-nliles competition then in progress would be completed, and they would have the ad vantage of some American guests being present. He would, however, call on any one present who would be unable to attend at the next meeting to move a vote of thanks to the author, and, at the same time, make any remal'ks on the paper that were necessary.

Mr. Shrapnell Smit h, in response to this invita­tion, said it was gratifying to those who took an interest in this subject to hear from Mr. Aspinall that his experiment had been so far satisfactory ; although the statements made had not been of so favourable a nature as the report received from the Corporation of Liverpool, who had purchased a vehicle previously, nor as that of the Dock and Harbour Board. There would be another compe­tition of the Liverpool Association in May. He wished to add, in proposing the vote of thanks to the author? how much.those interested in self-pro­pelled vehicles appreCiated the fact that the Insti­tuti?n of Mechanical Engineers had taken up this subJect, and a good many of those engaged in the 1000-miles competition regretted they could not be present.

Professor V ern on Boys seconded the resolution which was carried by acclamation. '

This brought the proceedings to a close.

PARIS EXHIBITION RAILWAYS. (Continued frt:nn page 547.)

THE second sect ion of the Exhibition line extends from the Avenue du Troco.dero station to the junction with the railway following the left bank of the Seine- the Moulineaux line. These works have been carried out by M. Bonnet, Ponts et Chaussees engi~eer, wh?, like M. Rabut, has kindly afforded us all Information. The entire undertaking has been under the general direction of M. Moise and M. Widmer, eDgineer-in-chief and assistant­engineer respectively, of the Western Railway of France.

On t~is section the work~ carried out were much more difficult and more original than those on the fir~t se?tio.n. The direction of the line may be br1e~y md10a.ted : beyond the Avenue du Trocadero stat10n, and the crossing beneath the Avenue

•

THE PARIS INTERNATIONAL EXHIBITION;

~-------- - --------------------------------r--­'

------ ------ ------ -- 1/:11/) 20 ----- ---------- - -- - -

•

THE COURCELLES-CHAMP DE MARS RAILWAY.

---- ------- .,-_______ _____ ,.. ____ ...,

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Fro. 10. LoNGITUDINAL SECTION FROM THE 'l'RocADERO STATION TO THE CHA?rfP DE MARS.

----- -- - · -- . - il --- . ----------- --------- ,. 'i---_::::::28.19? -"------~ ________ __ ______ r:. _______________ fl.2.:. ~9) _____ _

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Henri-Martin, the down track turns to the left and goes into tunnel, while the up t rack is deflected to the right to another tunnel that passes beneath the Ceinture. At a distance of about 50 yards beyond the crossing, both tracks come together, in open cutting, until they again enter a common tunnel, which is intetrupted for a length of 110 yards by a station. Beyond this is a tunnel for a length of 650 yards, and a short distance further the I Seine is reached at a point where the stream is di­vided into two channels by an island ; it is crossed by two steel viaducts, after which, with a curve of 348ft. radius, a j unction is made with the Mouli­neaux line near t he Champ de Mars station , which has been enlarged. (See longitudinal section, Fig. 10.)

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To go somewhat into detail, we may start with t he branching of t he two tracks from the Cein­ture. The exact spot was decided on after much consideration. At the point chosen, the Ceinture line has a somewhat sharp curve ; and, on the plan, at least, a tan~ent branch was, of course, easy. The Ceinture line, on leaving the Tro­cadero station has a rising gradient of 1 in 100. Therefore, by giving the up, or right-hand track of the new work, a falling grade of 1 in 100, a sufficient difference in level was soon reached, to obtain headway for an under crossing. The down, or left-hand, track was also given a falling grade, so as to meet the up line in the open cutting beyond the tunnel as already described ; in this way the

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E N G I N E E RI N G. - 579

THE INV ALIDES STATION OF THE COURCELLES-CHAMP DE MARS RAILWAY.

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danger of a level crossing was avoided. But this plan was attended with considerable difficulties, not only on a·ccount of the heavy traffic t hat had to be maintained on the Ceinture, but also because the tunnel crossed beneath the line at an angle of 14 deg. Moreover, the levels only allowed a dis­tance of .68 metre (26.77 in.) between the rails of the Ceinture and t.he extrados of the tunnel arch. The length of the tunnel is 75 metres (246 ft.) and the work was completed in two months and a half without accident, an average of 430 trains per day passing over the Ceinture line during the time. Fortunately the ground offered a good foundat ion, but it was impossible to drive the heading in the ordinary manner, on account of the slight depth. The method was, therefore, adopted, which had been successfully followed in making t he Paris extension of the Sceaux Railway.* The arch was built in short sections of about 10 H., on tem­plates formed by leaving a bolster of earth, brought to exact shape by a covering of plaster-of-Paris ; there were 25 of these sections, each being completed down to the footings before the next was commenced. In the tunnelled lengt h beyond, though many difficulties were met wit h, t he work could be carried on with the assistance of two shafts which gave additional working faces for the headings ; all excavated material, and that required for construction, was removed from , and brought to, the works by the shafts, so that the tracks were not encumbered with the contractors' trains. The headings were driven on the lines to be occupied by the side walls and footings of the tunnel. In that part of the work immediately under the rails of t he Ceinture the excavation of each section was in open cuttin.g; this ~volved the preliminary work of carrymg the ra1ls across each successive opening. F or this purpose longitudinal bearers were employed long enough to span t he opening ; t he bearers were braced together and further strengthened by a system of girders, the whole forming a sort of grill which was put in place in a few hours during the night, when there was a brief interruption to the traffic. The corresponding section of arching was completed on the plaster­covered earth centring above dQscribed, the mass was quickly removed, the side walls being previously constructed in. the open trenches prepared for t hem. The sohd nature of the ground, which was rock at the level of t he footu1gs, greatly facilitated this work. Those sections of the tunnel, which were partly under the Ceinture track, and partly outside were constructed o.n a mixed ~ystem ; the outer part~ were made b:r dr1 ven .headmgs, and the retaining walls of the Cemture Railway, where they were inter­fered with, were underpinned and carried in 10-ft lengths by oak beams. This work cost about

*See ENGINEERING vol. lix., page 101.

s8o 200,000 francs (8000l.) ; as it a voided the danger­ous alternative of a level crossing, the money was well expended, and might with advantage be imi­t ated in many other places. The L ondon Metro­politan widening at King's Cross affords a some­what analogous example. It remains to be added that ventilating and lighting shafts are made, open­ing into the retaining walls of the Ceinture lin6.

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Fig. 21.

E N G I N E E R I N G.

were 2.50 metres (8 ft. 2 in. ) wide, and of the same heigh t . The headings were afterwards lowered to the level of the springing of the arch, and close tin1bering was put in; the masonry then followed in short sections, and side headings were driven in which the masonry sides of the tunnel were built, also in short lengths. These latter excavations did not exceed more than 10 ft . in length at any one

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very bad, it was found necessary to excavate for lengths of 10 f t. to the invert level, and build it so as to pre\·ent the sliding inwards of the vertical side walls . Owing to the special conditions, and par­ticularly when passing beneath houses, great care was necessary in excavating the clay; the pick and shovel could not be used, and explosives were, of course, out of the question. R ecourse wa<3,

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As said above the two new tracks come t ogether beyond the t unn'el in a short length of_ op~n cut ting,

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this length being followed by the prm~tpal t_unnel I I on the line. The ground through whteh thts w~s constructed prmyed to be very ~nf_avo0:rable ; 1t consists at least down to the sprmgmg hne of the i- _ arch or' thin layers of limestone much dislocated by ~­cracks, many of large proportions. Bel?w t he arch f .. "f~;~~~ ~ springings a considerable depth of plastte cla~ rest- i 4--'-"'--

7 ing on marl was encountered . The constructwn of I I

the tunnel ~nder these conditions had,_ therefore, : * t o he carried out with great care, and ~1th ~he use ~ '?

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of close and heavy timbering. The dtmenswns of ; : this tunnel, which is interrupted by a ~hort length : -i- _ _ : of open cutting, are as fo_llow : 6. 5~ metres : ~'"" -- i: :

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(21 ft. 4 in.) between the ratl an~ the tntrad?s; ~ 5 1: : ~ metres (29 ft. 6 in.) between th~ stde walls, w~Ich ;,. _:t _ -~~~=::....::.::: """'+ _ :t are vertical ; the thickness of arch ts 1 metre(39. 3_tn.) SJN . IJ) ~+ozr~_. DZ

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at the top, and 1.25 metres (49.2 in) at the sprtn~- C.EMENT BEAMS AND R EVETMENT OF GIRDERS.

· the side walls are also finiShed to t lus 1 m g, · 90 t (3"" 4 · ) time, and the piers forming t_he s ide wa~ls w 1en thickness. The invert I S • me re o. to. . dl bl thick. The process of carrying Ol;lt the work was joined up, were put ID as rapt y as poss1 ~so as as follows : ~hafts were sunk at Interval~ on the not to leave the arch unsupported. After th~s :was

Centre ll.ne, and headings from these workmg face. s completed the mass of ea.rt~ and roe~ remamtng,

d d were removed down to the tnvert wluch was then were driven, the t op of which correspon e . to 1 h h d level witn the top of the t unnel ~rch ; t}lese drtfte constructed. I n some p aces w ~re t e ~roun was

therefore, had to a special class of work m_ en called "glaisiers," who are accustomed to deal w1th clay beds in brick and tile works, and who use tools that remove only small cubes of about 8 in. on a side. The work is very slow, especially as the tool has always to be used wet, otherwise ~t would not enter the plastic mass. All the matenal exc~vated was brought out in small wagons t?, and c~rrted across, the Seine over a temporary brtdge, whtch had_ been built On the other side these wagons were tlpped into iarger ones on a siding of the Mo_ulineau.x line, and taken outside PariE~, to be used In makmg up e10bankments for another railwn.y. I n order to insure solidity of work, it was found necessarr to inj ect liquid cement into the fi ssures of the hme­stone at the blck of the arch. This was done . as the work advanced, by means of compressed a1r ; about 250 cubic feet of liq uid cement ~ere. th~s used for each metre run of tunnel. V cnttlat10n 1s assured not only by the ends of the tu~nel, ~ut b_y a central shaft of 107 S<iuare fe~t area, m ~htch, tf it be found ne~essary, a fan dr1ven electncalJy can be placed. .

On this new Courcellcs-Cbamp de Mars Ratlway there is another work of considerable interest- the viaduct ta.kin~ it acro§B the Seine on a curve, and at

a very oblique angle (see Figs. 11 to 13, page 578). T]1e curve was n ecessary in order to effect a junction with the Moulineaux line before reaching the Champ de Mars station. The crossing of the river and the quays comprises a series of viaducts. Th~ first of these is askew span of 20.96 metres (68 ft . 8 1n.) over the roadway of the quay (see Fig.l3), and approached by five masonry arches; the secon d is a masonry via­duct spanning the lower road by the river ; a third is a gil'der bridge 81.71 met res (268 f t .) span. Then follows a masonry pier with an ar ch of 23ft . open­ing built on the island dividing the Seine at this place ; there are also three g irder spans over the further arm of the Seine, and finally a 13-metre ( 42 ft. 7 in.) land span across the quay on t he other side. This leads the railway to the Moulineaux junction. The principal part of this work was the 268-ft. span across t he mai~ branc~1 of the ~eine. I ts erection was attended wtth considerable d ifficul­ties on account of the heavy traffic on the river which could not be interrupted by the construction of staging, and only one span was possible, because the construction of piers was n ot permissible. Moreover, the level of the Moulineaux line at the point of junction was such that only a Yery limited headway was available. A scheme for a rigid sus­pension bridge was at first prepared, but was abandoned on account of the difficulty involved by the obliquity of the crossing. Another project for a lattice-girder structur e was negatived on the ground that it would look unsightly, so that t he arched bridge was the only alternative. The struc­ture consists of t wo arched ribs with large inter­section bracing, carrying the rail way by suspension rods placed 4 metr es (13 ft. 1 in. ) apart, excep t near this abutment . The structure appears very light, and the clear head way obtained is 7. 26 metres (23 ft. 9 in.), sufficient for the requiremen ts of navigation. The other arm of the Seine is crossed by the iron arches above referr ed to, and the design of which calls for no special comment. Figs. 11 to 13 are profiles of the Seine crossing, and show the relative positions of arches and girder spans.

The Champ de Mars station has had to be en­larged and considerably modified to provide for the great increase in traffic during the Exhibition ; the remainder of the work was the extension of the railway to the E splanade des Invalides, and the construction of the terminal station there.

E N G I N E E R I N G.

the Esplanade were very favourable, especially as t he existing quay wall had in any case to be taken down and r econstructed under different condi­tions. Ther e is a lower and an upper quay wall here as in most part of th e Seine within the city limits ; t he latter is much high er than the former, and serves as a h eavy retaining wall. As constructed, the line runs in cutting between this retaining quay wall on one side and a wall on th e other side, separating the rail way fron1 the lower quays on the bank of the Seine. This extension will be in open cutting for almost its whole length ; it will be electrically worked, for the Municipality, to say n othing Gf the people, will not tolerate any of the inconveniences in­separable from a Metropolitan railway like that of L ondon. It is covered by various existing streets and avenues, and, n ear the terminus, it curves away from the Seine in a short tunnel, which leads to the large underground station on the Esplanade des Invalides. This station occupies the whole width of the Esplanade between the two side streets that enclose it . The very large area thus obtained is entirely covered; in some portion by a system of columns, shallow girders, and brick arches, but to a large extent by thick sheets of glass resting on a girder structure, and through which sufficient light is ob­tained below. The station, of which an interior view is g iven in Fig. 15,'is a decorat ive building adjoining one of the streets t hat bound the Esplanade. Access from this to the numerous platforms is by a series of stairs; t he general arrangement is shown on t he plan, Fig. 14. One of the special accessories of the station is a considerable pum, ing installation. As the whole work is beneath the level of the Seine, it was n ecessary to provide means against p ossible inundations ; indeed, it is feared that this may prove from time to t ime a serious inconveni­ence, and even a possible danger.

Figs. 16 to 26 illustrate various types of construc­tion adopted on different parts of the Courcelles­Champs de Mars Railway. Fig. 16 illust rates the faQade of the Avenue Bois de Boulogne station. Figs. 17 to 20 are various views of the end of the covered way beneath the Avenue des Ternes, where the old Ceinture lines are in the centre in girder covered way, and the new lines, one on each side, are in brick arches ; an example of the use of the reinforced concrete is shown in Fig. 17, wher e the side walk of the Boulevard P ereire overhangs t he railway, and is supported on concrete slabs. Figs. 21 to 23 illustrate a type bridge crossing ; the one selected carries t he Rue Lalo over the railway into the Boulevard L annes. F our plate girders carry the road way over the track, the spaces between being filled in with jack arches ; the side walks are carried partly by the outside girders, and partly by brackets. Figs. 24 and 26 illustrate the method adopted of revetting the outer face of existing girders with concrete (Figs . 24) and the cross-section of a reinforced b eton girder (Fig. 26), of the type which has unfortunately been made so prominent by the r ecent accident.

As for the Champ de Mars station, the general arrangement adopted in 1889 has been maintained, but the number of tracks and platforms has been increased. There are now 20 lines and 10 platforms, all placed at right angles to t he faQade of the station building, in which there are 10 ticket offices, so as to provide for the great crowds that will cer­tainly have to be dealt with. This collection of tracks will serve both for an·ival and departure trains, the destinations of which are varied as far as possible, in order to prevent the inconvenience so prevalent on French suburban rail ways, of fre­quent change of carriages. Of t he 20 tracks, six connect with the Gare St. Lazare, running over the new line we have described. Two t racks will carry trains to the Moulineaux Junction, but for the Ceinture only : two others are also for the Ceinture service, but for that part on the left bank of the Seine, by way of a branch, that was built before 1889 ; four t racks will join the Gare du Nord following the Oein t ure on the right bank ; four are reser ved for passengers taking the line via Moulineaux to the western suburbs of Paris; and t wo will accommodate those passengers going towards Versailles by the branch not yet complete, between Moulineaux and Versailles. Although so much care and expense have been lavished on th e Champ de ~ars station, it is only to be temporary, and will dl.Sappear with the Exhibition. We have explained that the main object of the Moulineaux line was to bring railway accommodation towards the cen tre of Paris by its extension to the E splanade des Inva­v~lides. Before reaching the Champ de Mars sta­tiOn the line branches in the direction of the river and is continued parallel to the Seine ben eath th~ quay. AB, or nearly all, the trains coming from ~umerous directions enter the Champ de Mars sta­tiOn, but to provide for those passengers who desire to g? on .to t he Esplanade des Invalides, an exchange statt~n ls provided, so that visitors can pass from one hne to the other with but litt le trouble. When the Exhibition is over t his little exchange station will continue to serve as th e Gare Champ de Mars, and a goods depot will be established on t he site of the present temporary station.

In spite of the opposition of the Paris Munici­pality, i t is to be supposed that an extension of this line will be made to join that of the Orleans R ail­way, which is to have a terminus on the Quai d 'Orsay. Such an extension could, of course, be easily made, and would add greatly to suburban t ravelling facilities. Visitors to the Exhibition will scarcely see the Invalides station, except from the street outside its enceinte ; but in passing along the Avenue in the centre of t he E splanade des Invalides, they will walk over the glazed roof of the station. From the '~Street of Nations" the rail way is not visible, for although it has been constructed in open cutting, it is for the present covered by r einforced beton arches, on which most of the foreign pavilions are erected. There is no doubt that this part of the Pa.ris M etropolitan Rail­way system will be of great permanent utility to the city, and, later on, to the Exhibition esp ecially, but unfortunately it will n ot be available for the latter purpose immediately, since the electric trac­t ion station, being constructed by the Western Railway Company, is not quite complete.

The conditions for const~ucting the ~xtepsion ~o -

(To be oontinued.)

T HE RussiAN MERCANTILE MARINE.-At the date of a recent return, the R ussian mercantile navy comprised 604 steamers and 2294 sailing vessels. The steamers of the Russian mercantile marine are principally screws with one engine, but a few are of lar~er dimensiOns with two engines; these latter are used principally on the Ca-spian and l3laclc e~~s.

THE JAPANESE BATTLESHIP "AS A HI." WE give with this week's issue another two-page

plate, on which are reproduced the longitudinal sec­tion and the plan of the upper and main deok of t he new Japanese battleship Asahi, recently completed by Messrs. J ohn Brown and Co. , Limited, at t heir Clydebank works. The former two-page plate, which appeared with our issue of April 6, gave a profile and a plan of the boat deck. In subsequent issues we hope to reproduce further plans and sections, and need only here briefly refer to the illustrations on this week's plate. These are specially interesting as show­ing the great armament of this ship, which exceeds that of any of our battleships now afloat; for, in addition to the four large guns, of 12 in. bore, mounted in the t wo bar bettes there are fourteen 6-in. quick­firing guns, each in a separate casemate, t wenty 12-pounder, eight 3-pounder, and four 2~-pounder, and several Maxim guns of rifle calibre. The guns in the main battery are all of the E lswick type, and they were only shipped last week at Portsmouth Dockyard. with the sanction of the Admiralty. When leaving Portsmouth Harbour to proceed on gun t rials on Monday there was a slight hitch in connection with the steering gear, and wind and tide swung the hew of the ship round on to the beach. I t was ebb tide, but at the next Hood, at midnight, on Monday, t he vessel was easily got off, and will now be docked for examination; but the longitudinal section we repro­duce suggests sufficient strength to withstand a much severer trial t han was involved in this grounding on a gravel beach. It may be added that the Asahi has a displacement of 15,200 tons; her length between perpendicula-rs being 400 ft., and o,·er all 425 ft. 6 in. ; t he breadth extreme, 75 ft. 2i in.; and depth moulded. 43 ft. 7! in. With her engines developing 16,360 indicated horse-power, she attained a speed of 18.3 knots on a deep-sea trial, with a draught in excess of the contract ; t he design was for 18 knots.

AUSTRALIAN RAILWAYS.-Queensland is arranging to develop more rail ways. She is expected to place on the market shortly a 3, 000, OOOl. loan to be apphed solely to the construction of new lines. The New South Wales Railway Department will shortly call for tenders for 19,000 tons of 00-lb. flanged steel rails, 1420 tons of steel angle fishplates, and 220 tons of steel fish bolts and nuts. The Queensland Railwa-y Department bn.s let a contract for the erection of railway machine shops at Ipswich at a cost of about 200,000l.

---STEEL.-The exports of unwrougbb steel from the

U nited Kingdom in March amounted to 33,732 tons, as compared with 24,104 tons in Marc~, 1899, and 26,697 tons in March, 1898. In the three months ending March 31 this year, the aggregate exports were 91,448 tons, as compared with 65,608 tons in the corresponding period of 1899, and 73,357 tons in the corresponding period of 1898. The exports to Australasia in the firsb three months of this year were 10,372 tons, as compared with 7 420 tons and 721() tons respectively ; and those to Germany, 10,196 ton!l, as compared with 15,782 tons and 8780 tons respectively. No other country took as much as 10,000 tons.

---GAs AT P ARTs.- The Parisian Company for Lighting

and Heating by Gas has had an experience of 45 years (without taking account of the current twelve months), and during that long period the sales of the company's gn.s have made very great progress. In 1855 the annual consumption was 40,774,400 cubic metres, and in 1865 the total had been carried to 116,171,727 cubic metres. The sales steadily expanded during the next four years, until in 1869 a total of 145,199,424 cubic metres was attained. Then there came a great check in the company's opera­tions. Paris was besieged by the Germans in 1870, and was the seat of civil strife in 1871. The result of this terrible experience was that the consumption declined in 1870 to 114,476,904 cubic metres, and in 1871 to 87,481,346 cubic metres. The French, however, have a remarkable facility of overcoming difficulties of the most formidable character; and in 1878, which was an Exhibition year, the consumption of the company's gas had risen to 211,949,517 cubic metres. Then there was a. gradual advance to 287,443,662 cubic metres in 1884. The competition of the electric light now began to tell, and in 1885 the company's ga-s sales declined to 286,463,999 cubic metres, although they rallied again in 1886 to 2d6,851,360 cubic metres. There was then a gradual advance year by year to 3l2,258,070 cubic metres in 1889, when another great Exhi~itio_n was held ab Pari~. The competition of the electrtc hght now began aga1n to make 1ts adverse in­fluence felt, and in 1894 the company's gas sales bad de­clined t~ 300,823,710 cubio metres. In 1895 and 1896 they again recovered, a.nd in the last-mentioned year they stood at 318,020,060 cubic metres. In 1897, there was a decline to 315,308,270 cubic metres, but in 1898 there was a rally to 320,031,250 cubio metres, and in 1899 a further advance to 325,874,000 cubic metres. The general con­cl•1sion which may be derived from the company's expe­rience is tha.b while the electric light has not reduced the demand for the company's gas, it has greatly checked the progressive increase formerly observable in the consump­t~on ?fit. Th~ company shares its profits wit_h the muni­Clpahty of Paris. The aggregate length of p1pes laid by the undertaking in PariR and its suburbs was returned at the close of 1899 at 1541 miles. The capital expended by tpe Qompany a.t the sft,me date was 12,989, 765l.

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: E N G I N E E R I N G. • - •

THE DUDDELL OSCILLOGRAPH. CONSTRUCTED BY THE CA~IBRIDGE SCigNTIFIO INSTRUn!l~NT C0?\1PANY, LT~IITED~ CA~1BRIDGE.

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THE determination of the actual relation between the potential difference of an alternating current and the current itself in different circuit conditione has for long been a matter of considerable difficulty. I n certain simple cases the problem could be solved from theoretical.consi~lerations without much difficulty, t he more espeCially 1f the generator was such as to give a sine curve for the wave of potential, but with the types of wave curve common in commercial machines matters became more complicated. Further, as in t he case of an alterna te·current arc, data were wanting t o permit of any satisfactory prediction of the current wave, even when the wave of potential was of the simplest character ; and in other cases where t he nature of the circuit was better understood, i t was at least highly desirable to ma ke an cxperi· mental comparison between t he theoretiQal deductions and t he actual fae: ts of the case. The only methods aYnilable up to quite a recent date were highly laborious. These involved th c determinat ion of t he curves concerned point by point ; ana t hough much valuable research work had th us been accomplished by different ob crvers, t he time needed to complete a re­search was enormous, and in cer tain cases led t t t he abandonment of the attempt after the full mag­nit ude of the undertaking was completely appreciated. Some few years back Professor Blonde! succeeded in subst ituting, by means of an iHstrument he named an oscillograph, an autographic arrangement, for t he point-by-point method of curve tracing then in vogue, but t hough he did obtain some interesting results, his instruments did not come into general use, and it re­ma ined for a young English engineer to overcome the practical difficult ies involved, and to devise an inst ru­ment which seems capable of meeting t be se\ erest of re­quirements. Mr. W . Duddell, the gentleman in ques­t ion, in addition to his theoretical know ledge, is at the same time endowed with considerable manipulative skill, which enabled him to construct the first of t he inE~truments made with bis own hands, though much of t he work was of an exceedingly delicate cbaractu,

F IG. 1.

Fro. 2.

and t he instruments are now being made by t he Cam­bridge 1 cientific Instrument Company.

The instrument consists cs entia.lly of a modified D'Arsom·al galvanometer, combined wit h a rotat ing or vibrating mirror. I n this instrument the st rength of a. current is measured Ly t he angular displacement of a beam of light reflected from a mirror mounted on a. coil suspended in a strong magnetic field. The beam of light in question being received on a screen, t he st rength of a current is proportional to t he linear displacement of t he rEsultan t spot of light. With

alternating currents the spot of light reflected from t he mirror of this galvanometer oscillates to and fro as the current through its coil Yaries, and would t hus trace a straight line on a screen iuterpo ·ed in its path. In the oscillograph, bowevtr, a second mirror is inter­po P.d in the path of the beam, and this mirror is caused to vibrate by a cam driven by a synchronous motor, and there is thus added to t he beam of light a vibration at right angles to its original plane of motion , and it now t races on the scnen a cur ve of potentia l or current as the case may be. The apparatus is

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E N G I N E E R I N G.

THE DUDDELL OSCILLOGRAPH. CON TRUCTED BY THE CAMBRIDUE CIENTIFIC IN TRUMENT COl\IPANY, LIMITED, CA~JBRIDGE .

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shown complete in Fig. 1, whilst in FigP. 2 and 3 we j vibrated by the motor is thrown up on to t he curved show separately it s pt incipitl components. As will be screen above, as shown in Fig. l. A piece of t racing SfPn, the galvanometer and t he motor are placed in a paper can bo secur~d above t,his screen, and t he curve \\ oorl~n case. A lamp, fitt ed with a condenser of the pencilled in. Tho curtains shown keep out tray u~ual. type, is placed outside the case to the right, light, and enable the experimenter to follow the curve nnd tts light, passing through a vertical slot, is re- more easily. fiected back from the galvanometer mirrors, and passes The galvanometer constitutes the most important throng? a cylindrical lens cJearly shown in front of the part of the inst rument. Its magnetic circuit is satu­~otor 1D Figs. 1 and 2. This condenses the line of rated with a comparatively small energising current, hgbt to a. point, and this point fa.lling on a. mirror ~o that considera.ble changes in the latter have little

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influence on the strength of the magt1etic field in which t he moving coil or coils are placed. In the instrument shown there are two such coils, enabling simultaneous obsen ·a tions to be made on both current and potential. The coil in each case consists of a simple loop of phosphor· bronze, arranged as indicated in Fig. 4. The upper end of the loop passes round a pulley which is a ttached to a light spring balance, as shown in Fig. 3. By altering the tension of this spring, t he periodicity of the instrument can be varied at will. In t he instrument shown, t hese loops are but 7 mils wide by i'tr mil thick. Each lE>g of a loop pasees through a slot in a soft iron armature, thE\ clearance between the Eides of t he slots and the moving strip being but 1.5 mils, and t hese slots are then filled with a viscous oil, over which is placed a small lens, which is held in position entirely by the surface tension of the oil, and a.t t he ~ame time serves in its t urn to keep this oil in place. The object of the oil is to damp the oscillations of the coil. A small mirror marked !vi, Fig. 4, is attached to the loop, as shown. The effect of passing a current through one of these loops is to cause one leg of it to advance whilst the other goes back, and the mirror is thus oscillated round a vertical axis. In the instrument shown the natural period of vibration of the loop is

10 ~00 th of a second, and the clearances being, as I

stated, extremely small, the damping effect of the oil is very great, so that the instrument can be relied upon to give good curves even when the periodicity of the our­rent to be tested is over 300 altt-rnations per second. Small fuses, shown bolow the loops in Fig. 3, protect these from iojury in case of accidental excessive cur­rent . These fuses consist of very fine wires enclosed in gl~s t ubes. They are ht-ld in position by spring clamps. The motor, Fig. 2, has been specially de­signed for its work. It is a synchronous motor, on the armature ehaft of which is a. cam. This cam en­gages with a follower rigidly attached to t he frame carrying the vibra ting mirror. The shape of t he cam is such that it gives a uniform displacement to the point of light reflected from the mirror on to the screen a.boYe it. The return of t he mirror to its initial po itioo is effected by means of a spring, and during this back motion a shutter mounted on the motor shaft cuts off the light from the lamp. This shutter is clearly shown in Fig. 2. Provision is made for t9.king the load off the motor whilst the latter is running up to speed. The current required is but . 75 ampHe at 100 volts.

ome extremely interesting results have already been obtained with this apparatus. In particular, the remarkable researches on the alternating arc described in the paper road by Mr. Duddell and Mr. Marchant, before the Institution of Elect ricaJ Engineers, were made with the assistance of thi instrument. In these experiments photography was used to record many of the observations, the spot of light being received on a sensitive plate in place of ou a screen , the remark· able changes, in t he curves of potent ial and current, occurring on alterations being made in t he circui t con­djtions, being brought out in a very st riking manner. We reproduce here some of the curves obtained with

the same alternator and frequency, but with circuits differing in their self-induction or other particulara. Thus in Fig. 5 we have first the curve of potential difference for a Ferranti alternator when sending current through a non-inducti,re resistance of 3. 3 ohms in series with a resistance of 3. 04 ohms ; the potential difference curve across the termina]s of the latter is a lso shown, as well as the cur­rent curve. In Fig. 6 the resistance of 3.0! ohms is replaced by an arc, and the changes in form of the <.ltfferent curves are very striking. The potential dif­ference across the arc is, it will be seen, represented by a very fia.t-top curve, whilst the current cun·e is sharply peaked. In l?ig. 7 the conditions correspond to those in Fig. 5, save that one of the resic;tances is highly-inductive, and there is thus a considerable lag between the current and the potential difference of the dynamo. In Fig. 8 the circuit contains both self-induction and an arc. The frequency in all four cases is 100 alternations per second.

NOTES FROM THE NORTH. GLASGOW, W ednesda.y.

Gla~gow Pig-Iron MMket.-At the forenoon session_ of the pig-iron warrant market last Thursday a firm feehng ruled a.b the opening; but the selling of Scotch iron became rather pronounced, a.nd there was a sharp set­back. The close was fi!l.t, with Scotch down la. O~d. per ton at 72d. 7d. Hematite iron fell 2d. per ton, but Cleve­land was unchanged. In the afternoon the market was irregular. Scotch was very flat, and closed l s. 4~d. do~n on the day, and Cleveland fellls. per ton; but hemati~e iron was supported, and closed ld. per ton better than m the morning, or only ld. down on the day. The sales for th& da.y amounted to 40,000 tons. Cleveland was ~old at 693. 6d. per ton six months fixed. The settlement pr1ces at the close of the market were : Scotch 72s. 3d. per ton ; Cleveland, 75s. 9d. ; Cumberland and Middlesbrough hematite iron, 845. 3d. and 86s. per ton. The m~rket opened on Friday at 72~. 6d. per ton for _Scotch Iron, and receded to 72~. 2d., but afterwards 1mproved to 73s. ld. per ton, closing with buyers at 733., the settlement prices being 73s., 763., 84.s. 4~.d., and 863. per ton. Owing to the unexpected calhng up of. a large quantity of hematite iron, the afternoon sees1on was excited, and the prices had a very ~m~rt ride, Scotch rising 9~d., Cleveland 4~d., and hemat1te u on id. per ton. The reports as to the condition of the iron tt:ade m America were somewhat mixed on Monday mormn~, but! they were generally regarde~ as unfavourable. Busi­nefiS in the local market was qmefJ, only some 10,000 tons, chiefly Scotch, bE'ing dealt in. The price fell 7~d . . per ton, and Cleveland gave way 9d. per ton. The deahngs in hematite iron were few, and were only for ~xed periods, as a result of the calling up announced on Frld.a.y. The prices rose l!d. per to~ and the settlement pnces were: 7b. 9d., 75s., 8-!s. 3d., and 86s. per ton. On account of the calling up of hematite iron, and the ~hreat~ned squeeze in tha~ claes o~ i~on, there was exceedmgly httle bueineas done 10 the pig-uon market on Tuesday forenoon, when less than 10,000 tons changed hands. For the same reason the feeling amongst ope~ators 'Ya~ very .n.erv<?us, and prices were strong, there . ~mg a dl.S~l~ct dismchna­tion to sell under the existmg conditiOns. . Sc<?tch rose lO~d. per ton. Cleveland 4~d., and hema.t1te uon 9d. per ton. ~n the af_ternoo~ the market was ~tea.dy, very little bus10ess domg, st1ll the turnover d1d not exceed that of the forenoon session. It was repor~d ~hat warrants representing about ~,000 tons of bema.tite 1ron were lifted and some Scotch uon was also called up; but in the latter connection it was. &"iven out that the movement had nothing to do Wlth. a. squeeze-that it simply had relation to the squarmg of an open account. Scotch and Cleveland. w~re unchanged from the forenoon close; hematite uon ga.ve way ~d. per ton, there being leas nervousness over the threatened squeeze. At the close of the market the settlement pr1ces were: 72s. 7id., 75s. 3d., 8~s .. 6d., an~ 8GJ. per ton. The market w.as i';l a_very sen~Itive con~l­tion to-day. The squeEze lS still m force 10 hema.tite iron, which rose in the forenoon 4~d. per ton. Abo~t 13 000 tons of iron changed hands, and 10,000 tons m th~ afternoon. The settlement prices were: 7~. nd., 75s. 3d., 84s. 9d., and 86s. per ton. The f~llowmg are the current quotations for makers' No. 1 uon: Clyde, 893. Gd. ; Gartsberrie, 90s.; Summerlee an~ Cal~er, 9La.; Coltness, 93s. 6d. per ton-all the foregomg sh1pped at Glasgow; Glenga.rnock (~bipped a.b Ardrossan), 88s .. 6d. ; Shotts (shipped at Leith), 90s. 6d. ; Carron _(shtpped at Grangemouth}, 90d. per ton. Here are given the shipments of pig iron from all Scotch porta for the we~k ending lasb Saturday : Fo~ the United States 200 to';IS; for Canada, 267 tons; for Indta, 120 tons ; for Austraha, 407 t ons· for Italy 225 tons; for Germany, 940 tons; ~or Hol­land; 1074 ton~; lesser qua~tities to other countnes, and 2709 tons c ::>astwiae. The shtpm~nts for the week a~ounted to 7597 tons against 5983 tons m the correspondmg week of last year 'and the total shipments for the year amounted to 186 090 ~ns as compared with 86,138 tons ab the eall?e date ~f last y~a.r. The fluctuations of the. past we~k 10 the pig-iron market were ~oth rapid and vi~lenb, swayed up and down by ever-varymg and C?ntra.dic~ory r~<?rts received as to the state of the trade m AmeriCa. . ncea have aho been influen?ed adversely by the contmue~ absence of all fresh buymg, whether on home. or o~. Con tinental acconnt, and makers h~reshow so~edis~sition to meet the market with concea~10ns on thetr offimal quota­tions Speculative dealings 10 warrants ha.ve been on a very ·large scale, and some interes~ing developments may be looked fo: in west coast hematite brands, as attempts

E N G I N E E R I N G. are being made to manipulate the Glasgow market. The furnaces going ab present number 85, of which 40 are making ordinary iron, 3!) are working on hematite iron­stone, aad six are making basic iron. At this time last year there were 83 furnaces in blast. ~be stock of pig uon in Messrs. Conna.l and Co.'s pubhc warrant stores stood at 154,827 tons yesterday afternoon, against 150,107 tons yesterday week, thus showing a reduction for the past week amounting to 4280 tons.

Finished Iron~ Steel.-The sizing up of the Scotch manufactured iron trade is becoming increasingly diffi.cul b, for with the severe break and ultimate rally in the apecn­lati ve branch, brokers are at a loss as to how to de.al with quotations. Prices cannot well be reduced, so h1gh are wages and fuel charges; and, on the other hand, some m_ove is called for if fr~sh orders are to be attracted. AdviCes give it that the Belgians and Americans have both shaded prices, although, on the other hand? t~e prospect of the federating of the bar-iron trade associations sho~14 have a hardening and assuring effect on . the trade. po~ItlOn . . It is evident that the sreat productive capaclty lS gettmg abreast of consumptiOn, and when that ~act is f~lly r~­cognised makers will be forced to consider their posi­tion. Sheet iron is in satisfactory request, a.nd steel rails are asked for. Local makers, as recent contracts go to show, are s~ill en~bled to compete success­fully with the fore1gners m neutral markets. Scotc.h steel workers are asking 5 per cent. of advan~e. Th~u leaders base their calculations upon the pnce which the masters are asking for material, hub which the.y ~re not getting. Indeed, makers assert that under ex1stmg circumstances steel plates a.t 8l . 15s. per ton do not pay them. Steel angles are quoted at 8l. 5s. ~o 8l. 7s. Gd. per ton; ship-plates, 8l. lOa. to 8l. 12s. 6d. ; b1llets, 7t. 15s. to 7l. 17a. Gd.; raild, 7l. 53. to 7l. 10s. per ton. Bars are again quoted at Dl. 15s. to lOt. lOa. per ton. ~f otherwell Bridgebuilding.- The Brand on Bridge­

building Company have secured the_ ?Ontrac.t for the viaduct at Yorkbill of the North Bnhsh Ratlway. Io will be remembered that the viaduct was destroyed by fire in March. The Parkneuk Bridge Works Mother­well are very full of orders just now, both for home and foreign requirement~, although they ba.':e just g~t out of their hands the steelwork of the termmal sta.t10n and ~oods yard a.t Marylebone-road, L ondon, for tha Gr~at Central Railway and the steelwork for the power stat10n and car sheds for Edinburgh Corporation. At present they are engaged with the manufacture of t~e steelwork for the ~rand concert ball for. the forthc~mm~ Glasgow Exhibit10n, and bridges for ratlway extens10nstn Lanark­shire and elsewhere.

Sulphate of Ammonia.-Tbis commodity is weaker in demand spot business having been done on Monday at lll. 7s. '6d. per ton f.o.b. at L eith. The shipments of sulphate at that port for last week amounted to 168 tons.

Glasgow f!opper Market.-No ~usiness has been done in col?per durmg the week, and pnces have generally been qu1te nominal, ranging between 76t. 5s. per t9n and 78/. No change to-day.

Engineer to the Clyde Trust.-A meeting of the Com· mittee of Management of the Clyde Trust was ~eld le:st week, Dr. U re presiding, when amongst other thmgs di.s­cussed was the subject of the filling up of the vacancy m the official staff occasioned through the recent death of Mr. J a.mes Deas, the engineer-in-ch~ef. After ~ rather protracted discussion, it was unammo~sly decided to appoint Mr. William Murray Alston engme~r at a sa.la~y of i50l. per annum, and to appoint Mr. Archibald Hamil­ton outside superintending engineer at a salary of 600l. Mr. Alston has been 34 years ~t least in. the employment of the Trust. He a~ted as rea1dent engme.er at the con­struction of the Queen's Dock, and be was r!_ght-~and ~an to Mr. Deas in Parliamentary work. Mr. Hamll_to~ hke­wise has been long connected with the Tru_st, prmc1 pally superintending outside work.. He was res1denb engmeer during the erection of the Pnnce's Dock.

NOTES FROM SOUTH YORKSHIRE. SHEFFIELD, Wednesday.

Gas-Making Difficulties in West Riding.-~everal im­portant points have arisen between the Ass~Clated Coal­owners of South Yorkshire and the C<?rporat10ns of ~eeds and other big West Riding towns, whtch, unless amicab!y arranged, may very shortly lea_d t<;> a new departure m gag production, if not a revolution In t~e ~ethods of coal sup.Ply. The Associated Coalowners, It lS state~, seek to msert in future gas-coal ~ontrac~s terms !f'h~ch .the Corporations unite in regardmg as uks<?me, Irntatmg, and unfair. The latter have entered a. vigorous Pt:otest, and have informed the colliery proprie~ors tha.t If the new terms are insisted upon, steps w11l be taken to restrict the purchase of coal : one of the mean~ to th~t end being the use of carburetted wa~r-gas, wh1ch, as 1s well known, not only acta as an .enr1cher, but renders a large percentage of cannel c~al superfluous. The Cor­porations epecially concerned m the ?latter are t~ose of Leeds, Bradford, Huddersfield, ~ahfax, and Keig~l~y; and suggestions have been made ~n favour of mummpal combination in colliery undertakmgs, S~<?uld_ th~ worst come to the worst. In. this age of ?lUDlClpaheatlOn, t~e question of corporation co~l-gettmg, for the pubhc benefit, is doubtless one that m the near .futur~ ma.y be added to the rest. Leeds is about to acqUire a .big esta~ for sewage purposes a.t Gateforth, under which coal 1s said to be found .

N ovel Armoured Trains.-An interesting feature of the visit of the Institute of Suryeyo~s to Leed~ last week was the inspection ab the engmeermg esta.bh.shment of Messrs. John Fow)er .and .eo., ~imited, of part of an armoured train whiCh lS bemg bUilt by the firm for ufe

with the British forces in South Africa. The wagons inspected formed a portion of two trains which are to be despatched by order of the Govern!Dent at the e':ld of May. The traina do not run on ratls, but are designed for use on the veldt or on roads, to be drawn by traction engines. The wagons are bullet-proof a.t 21) yards, and have openings for long field guns.

Sheffield Di~trict .Railway.- The opening c~romon.y, which has been fixed to take place on May 21, wtll cons1sb of a trip over the line and on through Beighton toE~ win­stowe, returning to Sheffield, where luncheon will ~ served in the Cutlers' Hall. The Duke of Portland will be the principal guest.

Iron and Steel.-The reports of the condition of the heavy branches of trade continue to be extremely satis­factory, and at all the iron and steel wor~s men are being found full empl~yment. In the f~undnea de_voted to the turning out of Iron a.nd steel castmgs there 18 the greatest activity, the demands for ~11 kind.s of w~eel.s a.nd parts of electrical and other macbmery bemg specially heavy. Manufacturers of dynamos and motors are well off for orders, and there is a. well-sustained demand for all descriptions of engineers' tools, especially for_ anvil~ vices and heavy hammers. A very large busmess 1s being done in gas and oil en~inea, as ma~y manufactu~ers are adoP.ting them and clea.rmg out thetr present engmes and botlers. Apart from Government. orders, the file trade is quieter t hat?- it ~as, and there IS .a great deal of slowing down of busmesP m almost all articles of luxury. Manufacturers of edge tools, pen and pocket c~tlery and scissors, are seriously hampered by the scarcity of labour.

South Yorkshire Coal.-A feature of the coal trade in the district this week is the inquiry from many of the principal __gas companies for tenders !or supplies, com­mencing July 1 next. The compames, as a rule, a~e asking for a much larger tonnage than was the case m last year's contract$, with the object, it is assumed, of securing better terms. Colliery owners, however, do not seem inclined to respond to their req nests, on account of the very heavy demand a.b present existing from all quarters. The contracts which have been already entered into for supplies for next year have been made ab advances of at lea.gt 6s. per ton. An increasing demand exists for coal for export purposes, the inquiry f<?r home consumption being also very Ja.rge. House coal 1s some­what easier· but while in coke for foundry and steel­purposes, va.iuea are steady, blast-furnace coke is selling at fully ls. per ton more than was the case a. month ago. In Sheffield prices are as follow: Mortomley, 16s. 6d. per ton ; Silks tone branch, 16s. per ton ; W allsen.d 15s. p~r ton; picked large Silkstone, 15s. per ton_; Htgb Hazles (hand picked), 14s. per ton; screened ~1gh Ha21les and Silkstonea, 13~. 6d. per ton; Barnsley p1cked house, 14s. per ton· ditto seconds, 10s. to 12a. per ton; Ba.msley bards, lSs. to 14s. per ton; ditto, unscreened, 11~. to 12d. per ton; Parkga.te bards, 12s. ud. per ton; steam nuts, 10~. 6d. to lla. per ton ; best Barnsley slack, 93. to !>d. 6d. per ton· pit slack, 7s. 6d. per ton; foundry coke, 28s. per ton; steel ·melting coke, 26s. per ton; blast-furnace coke, 22s. 6d. per ton.

NOTES FROM CLEVELAND AND THE NORTHERN COUNTIES.

MIDDLESBROUGH, Wednesday. The Cleveland Iron Trade.-Y esterday there was only

a thin attendance on 'Change, the mar~eb ~~ dull and very little business wa.s done. A few 10qmnes were re­ported, but they led to little business, as pi.g iron was ex· ceedingly scarce, and buyers and sellers d.ttfered a good dea.l in their ideas a.~ to what should be paid for early de­livery. Little or no disposition was shown to do business ahead makers being well sold a.nd purchasers well bought. At th~ sa.me time, confidence was felt in the fature1 and reports of pjg iron having been bought. on .the <;'ontmenb and in the United States for consumpt10n 10 th1s country had little effect on the market!. 'l'he general market quotation for l?rompb f.o.b. delivery of No. 3 g.m.b. Cleveland pig u on was 77s. Sellers, as a rule, would nob quote below that figure, but, on the other ha.nd, buyers endeavoured to purchase at considerably les~, some of them offering as low as 753. No. 4 foundry p1g was about 76s.; grey forge, 75s. ; and mot~led and white, 74s. 6d. Middlesbrough warrants were qmet thro~ghoub the day a.t 75s. cash buyers. The nominal quotation for Nos 1 2 and 3 east coast hematite pig iron was 87s. 6d., but th~r~ was absolutely none to be had. Mi9dlesbrough hema.tite warrants were not quoted. Rub10 ore w~ 2ls. 6d., ex-ship Tees. There was no change whatever m the market to-day.

Manufactured Iron and Steel.-In all departments <?f the manufactured iron and steel trades a. lo_b of work 18

going on, and most firms have orders t~at wtll keep them fully occupied for a month or two. It 1s understood thab more orders have to be given out s~ortly, ~?ut those who have the placin~ of them are holdmg off m the .hope of easier rates ruhn~. Up to the present, quotations a.re very well maintamed. Common iron bars are. 9l. 10s.; beat bars, lOl.; iron ship-plates, 8l. 10s.; steel sLip-plates, 8l . 7s. 6d.; iron and steel ship-angles, 8l: 5s. to 8l. 7a. 6d. -alll~s the customary 2! per cent. diScount for cash. Heavy sections of steel rails are firm at 7l. 15s., net ab works.

Rumunvr of Armour-Plate Works fo r Tees-side.-There are rumours afloat that armour-plat~ works ar~ to be esta· blished at Middlesbrough. It 1s said that a Site ha.s been purchased on the river side below Cargo Fleet, and for· merly belonging to the Cargo Fleet Iron Company, Limited. Negotiations are a.lso reported to have_ passed with the Tees Consenancy Commissioners regardmg tho

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river frontage. and arrangements for shipping facilities. Notwithstanding the circumstantial statemen ts, many business men here discredit the report. There are others, however, who believe that the establishment of such works is very likely, as the district is admirably suited for such a. purpose.

Shipments of I ron and Steel.-The shi(>ments of iron and steel from the Tees and from Skinrungrove during April were very satisfactory, reaching a grand total of 167 419 tons. Of this, 11,100 tons of pig iron were sent tro:U Skinningrove, 106,839 tons of pig iron from Middles­brough, and 2l,109 tons of manufactured iron, and 18,371 tons of s teel from Middlesbrough. Germany was the biggest customer, taking 49,109 tons of pig iron, Holland came next with 20,792 tons of pig, Scotland took 9075 tons of pig, Italy 6500 tons, and Belgium 4228 tons. The largest customer for manufactured iron wM India, with orders for 4742 tons. and the mo~t steel (7672 tons) was sent to Portuguese East Africa..

Coal a;nd, Coke. -The demand for bunker coal is s teady, hub the supply is good and quotations are unchanged. Gas coal is firm, and this week very heavy shipments have been made to the south. Manufacturing coal and coking coal steady and strong. Coke continues in very goo? request, and m~dium bla.at -fur?a.oe q ua.lities are selling a.t 28s. 61 , dehvered at Tees-stde works over the next half year.

NOTES FROM THE SOUTH-WEST. Cardiff.-The demand for steam coal has continued

good. Colliery managers have not been in a position to accept much new business in connection with which prompb delivery is insisted upon. The best steam coal ha.s made 2ls. 6d. to 22~. 6d. per ton, while secondary qualities have brought 193. 6d. to 20s. per ton. The house coal trade has shown little change ; but, of course, busi­ness in these qualities has fallen off with the advance of the season; No. 3 Rhondda. large has brought 2ts. to 2Z3. per ton. Coke has made about former terms, foundry qualities being quoted a.t 323. 6d. to 33s. 6d., and furnace ditto, ab 303. to 3ls. 6d. per ton. As regards iron ore, the best rubio has made 20s. to 20s. 6d. per ton.

Bute Shipbuilding, &c., Complllny.-The report of the directors of the Bute Shipbuilding Engineering and Dry Dock Company, Limited, for the year ending March 31, 1900, observes: "The balance to the credit of the profit and loss account for the year. after allowing for deprecia­tion, &c., amounts to 17,987l. 4.s. 9d. An interim divi­dend a.t the rate of 10 per cent. per annum was paid in September, after providing for which there remains (including 33,269l. 5s. 1d. brought forward from the last account) a. balance of 42,506l. 9s. 10d. available for divi­dend. The directors recommend the payment of a further dividend at the rate of 10 per cent. per annum (free of income-tax), which will amount to 8750l., leaving 33, 756l. 93. 10d. to be carried forward. "

Wirelus Telegraphy.-Signor Marconi's system of wire· less telegraphy was further tested at La.vernock on Tues­day, when messages were transmitted to Weston-super­Mare without any fault being observable. Some sub­stantial alterations had been made, Marconi's cylinders having been substituted by strips of wire gauze; and the most essential feature of the scheme-the coherer-having been altered. It is not unlikely that, owing to the fact that the military authorities require the sole control of the fort at Lavernock, but few further experiments will be made there. Should L avernock be not available, trials will pro­bably be made between Ilfracombe and the Mumbles, a distance of 25 miles.

Glov..cester.-As a result of a. recent inquiry, an intima­tion has been received that the Local Government Board will be prepared to issue a. provisional order for including in the city adjacent parishes representing 800 acres. A scheme of the town council provided for the addition to the city of 6451 acr~ .

Swansea..-At a meeting of the members of St. Thomas, s~. John's, and Landore Wards at Swansea OD Wednes­day, a resolution was passed instructing the borough surveyor to prepare plans for a footbridge over the river from Hafod to F oxhole, on lines suggested by the sur­veyor. The bridge will cost between 15, OOOl. and 16, OOOl.

The South Wales Institute of Engineera.-The forty­seco!ld annual meeting of this society was held at the Ins~ttute, Park-place, Cardiff, the chair being occupied du!lng the. earlie! portion of the proceedings by the out­gomg prestdent, Mr. H. K. Jordan, F.G.S., who subse­quently re3igned it to his successor, Mr. Thomas Evens, M. Insb. C.E. Mr. Evens' inaugural address ra,l)ged over nearly every department of engineering. With refere~ce to the coal industry, he gave figures according to whtch the world1S output of coal had risen from 393,695,000 tons in 1889 to 627,250,000 tons in 1899.

CATALOGUEs.-The Atlas Engineering Company, of the Atlas Tool Works, Levenshulme, Manchester, have sent ~-a. copy of. their new illustrated catalogue of lathes,

rillih ng machines, planing machines, milling machines, and ot er tools.-We have received from Messrs. N. C. Szerelmey and Co., of Rotherhithe New-road, S.E., a copy of a. paii_lph~et describing applications of the stone-pre­servmg liqUid and paints made by the firm.-Mr. R. J. Moss, of 97, Great Hampton-street, Birmingham has rent us a catalogue of generators and fittings for ~ty-ene ~.-M~rs. Joseph Adamson and Co., of Hyde, Cheshire, have 1SSned a list of the fianged plates they are prepared to sup.PlY. to the trade, together with the prices of same. The hst moludes a very la.r~e variety of boiler­end plates, manhole fittings, and the hke.

E N G I N E E R I N G.

MISCELLANEA. THE b·on A ge is responsible for the statement that a

train 6000 ft. long wa.a recently hauled over a certain portion of the Cleveland and Pittsburg line. The brake­man in the van at the rear of the train had to telegraph the order to start to the engine·driver in front.

By alloying aluminium with tungsten, M. H. Partin claims that a metal can be obtained, having in its oast state a specific gravity of 2.89, and a tensile strength of about 9 tons per square inch. The same metal rolled has a den­sity of 3.09, and a tensile strength of 22 tons per square inch.

The Council of the Sanitary Institute have arranged to hold the Institute dinner on Friday, May 11, in the Vene­tian Chamber, H olborn Restaurant. His Royal Highness the Duke of Cambridge, K. G ., President of the Institute, has consented to take the chair. Tickets can be obtained from the secretary at the Parkes Museum, Margaret­street, L ondon, ,V,

The annual dinner of old students of King's College, L ondon, will be held at the Holborn Restaurant on Mon­day, June 18, with the H on. Sir J ohn Alexander Cock­burn, K.C.JM:. G., F. and A.K.O .• M.D., Agent-General for, and formerly Premier of, South Australia, in the chair. His Royal Highness the Duke of Cambridge, KG., has signified h:s intention of being present.

The traffic receipts for the week ending A pril 22, on 33 of the principal lines of the United Kiogdnm. amounted to 1,801,509l. , which was earned on 19,865f miles. For the corresponding week in 1899, the receipts of the same lines amounted to 1,746,789l., with 19,604} miles OJ?en. There wa.s thus an increase of 54, 720l. in the rece1pts, and an increase of 261i in the mileage.

The North Sea.-Baltic canal still fails to pay its working expens~, though, of course, as its construction was due to strategic and not commercial consideration~, this was only to be expected. The traffic is, however, increasing. the tonnage passed through in 1898 totalling 3,117,840 tons, an increase of 26.24 per cent. on the preceding year. The receipts were 1,634,337 marks, and the expenses 2,066,737 marks. The average time of transit was 8 hours 43 minutes for boats nob exceeding 17.7 ft. in draught, and 11 hours 30 minutes for boats drawing between 17.7 ft. and 22.6 ft. of water. The time taken in {>&SSing the locks a.t the Baltic end has· averaged 8 mmutes; whilst at the North Sea. end, 17 minutes has been required.

Plant for automatically charging blast-furnaces has recently been erected at the Zanesville furnaces of the National Steel Company by the Brown Hoisting and Conveying Company. An inclined girder is constructed from below ground level up to the top of the furnace, and is provided with rails on which runs a skip of 100 cubic feet capacity. This ~kip, after being filled at the bottom, is hoisted by a small engine, overwinding being pre­vented by an automatic stop, which shuts off steam when the oar has reached the proper point for dumping. The bell and the hopper doors a.b the top of the furnace are all regulated from below, and a regtstering device is pro­vided which records the height of the stock in the furnace every time the bell is lowered. The whole of the work of hoisting and filling into the furnace is done by a single man, who is much less hardly worked than the men replaced by the machine.

The Board of Trade inspectors have of recen t years repeatedly called attention to the slackness of British railway companies in adopting some mechanical method of fog signalling, which would, at any rate, insure the safety of trains until the fogmen can get to their places. According to the .Railroad Gazette such a system has been in successful use on some of the New York lines since 1892. The trouble with such systems lies in the fact that in case of failure of any portion of the mechanism, no danger sign al is given, the ideal system of signalling being on the other hand one in which the absence of a positive signal to proceed, means danger. Even so, how­ever, the adoption of this system would go far to reduce the accidents which now occur before the fogmen can get to their posts, and we do nob believe that the problem of mechanically giving a. positive signal for safety, and for safety only, is by any means insoluble.

~he water works of. Daw:son City, on the Klondyke RIVer, are probably umque m the world. The supply is pumped from a well sunk in the river valley, into a tank holdmg: about 8000 imperial gallons. This tank is en­closed m a house heated by a stove which maintains a temp~rature inside of about 50 deg. Fa.hr. The water as it comes from the well has a temperature of about 35 d eg. to 36 deg. Fa.hr. From the tank the water is pumped to a number of hydrants, from \vhioh the supply is drawn by the consumer as needed. These hydrants are all housed within wooden shelters having double walls, the space between being filled with sawdust. A stove in these shelters keeps the water from free7.ing. The water is kept in constant movement, being, we gather, pum~d back to the main tank where ib is reheated. One dlffi. oulty meti with on the part of the water company is the very considera.blf;\ loss by theft, estimated to amount to one-third of the total supply. To oheok this, it is pro­posed to institute some form of penny-in-the-slot meter similar in principle to the prepayment gas meters no~ so common.

An American engineer resident in the Rand reports in the Engineering and Milnimg Journal, that the Trans;aa.l Government adopted a very simple plan of reduci~g the working expenses of the mines operated by them. Under company management the native workmen were paid 4l. per month, plus food and lodging, hub the Government cut this down to 1l. in the mines operated by them ; and

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even this amount was paid under protest, so to speak, as they claimed the right to make the negroes w<?rk f~r nothing. And the same time that they agreed to gtve th1s compassionate allowance, as it may be called, they decreed that no Kaffir labourer anywhere in the country should be paid more; but it has been found impossible to adhere to this striotl;r, in the case of natives who had facilities for esoa.pmg, such a.s th<:>se employed on the railways. In the oase of the mme labourers, however, the decree has been enfor~d ; a.~d though under ordinary conditions such a. dra.st1c cut m wages would be followed by a fa.lling-otf in the efficien~y of the labourers, this, it is believed, has not foJlowed 1n the present ir.stance, since the correspondent states that the Dutch officials who are now in control underata.nd the management of natives better than EnglishmenA Presumably the frequent and forcible application of "sj ambok , forms a prominent feature of their &3Stem of management.

Observations on the propagation of sound have shown that under certain conditions a very loud noise is trans­mitted more rapidly than less powerful ones. Some experiment3 bearing on the same subjeot, viz., the pro­pagation of very violent waves, have recently been made by M. Paul Vielle, the inventor of a smokeless powder adopted by the French Government. Theory shows that if a. wave front becomes perpendicular, the ordinary Jaws of wave movement cease to &J;>ply, and this condition is readil;r attained with explos1 ve waves. In M. Vielle's experiments a steel tube about 1 in. in diameter and some yards long was provided with recording pressure gauges at different points through its length. On de­tonating charges of powder or fulminate near one end of the tube the pressure gauge nearest the point of explosion recorded a gradual rise of pressure, but the records taken further along the tube showed that this wave front quickly became vertical, and from this point the pressure gauges gave deceptive indications since the rise of pres­sure was so abrupt that the inertia. of the moving parts of the gauges vitiated the record. After the wave ha<i, however, travelled still further it lost its steep­ness of front and took, again, the usual wave form, its velocity falling therewith to that of sound. With the vertical wave front the velocity of propagation was always much greater than this. It is suggested that these experiments gave an explanation of the fact ths.t the barrel of a shot gun can be bulged by {>lugging it near the muzzle and firing a cartridge with 1t in this state. In these conditions the explosive wave has acquired a vertical front before reaching the obstruction, and a.ccord­ingly the rise of pressure there on the arrival of the wave is enormous. An ordinary wave passes through a. fluid medium without taking up or giving out energy, both expansion and contraction taking place automatically; but, with a vertical fronted wave, this is no longer the case. Energy is given up to the medium, which is heated thereby, and this loss of energy finally re~ults in the me~hod of propagation being at length reduoed to the ordma.ry wave type, in which condition the velocity is equal to that of sonnd.

LEAN's RoYAL NAVY LrsT.-We have reoeived from Messrs. Witherby and Co., 326, High Rolborn, and 4. Newman's-conrt, Cornhill, the April issue of " Lean's Navy List." W e have so frequently written in a. com• mandatory way of this comprehensive and well-arranged Navy List that it need only be said now that the new issu~ embraces all recent changes, including the South Afncan war honours. It should be remembered that thie list gives a narra.ti ve of the war and meritorious services, &c., and of all officers- an interesting record not found in other similar publications.

THE WEAR.-An agreement was concluded on Fridaty between the committees acting for the Sunderland Town Council and the South wick Urban District Council with reference to a bridge which it is proposed to build over the Wear between Southwick and Deptford. The chief points of the arrangement are that the Town Oounoll will pay 140,000l. towards the cost of the bridge, and make the south approaches which will cost about 20 OOOt. The ex­penditure on each side will be returned by tolls and after· wards 10,000l. will be allowed to accumula.'te for the expense of keeping the structure in repa.ir, the bridge then to be declared free.

- - -. THE BAOT~R~AL TRE.ATMlpYT Oli' SEWAGE.-A capital

httle book, gt. vmg an htstonca.l survey and details a.s to the mode~n method of treating sewage by biolysis, has been pubhshed by The Councillor and Guardia!n of 29 Old ~ueen-street, S. W. The author is Mr. he~rg~ T~ud.toh~m, F.C.S., who _has been associated with Mr. Dtbdm m a number of unporbant applications of the syste~. .To those who already have some knowledge of. thts Important departure in the disposal of the dejecta. of our towns and cities, the most interesting part. of ¥r. Thudiohum's pamphlet will be that dealing wtth trade wastes. These differ much in ohara~ter. Some, such. a.s brewery wastes, are, Mr. Thud10hum states, unemted for septic tank treatment • but can readily be rendered innocuous by a.erobi~ method~. At. Yeovil, on t~e othe~ hand, where the sew~ge IS parbtoularly obnox10us owmg to the large pro. port10n . of. fell mongers and leather -dressers' wastes in­cluded m ~b, the s~ptic tank supplemented as usual by tr~tment 1n. aerobto beds, has proved successful in pto­ducmg a. sa.ttsfaotory effluent. In Scotland these bene ficent bacteria. bid fair to save the threatened destruotio~ of the salmon streams ~y distillery wastes. In faob, it ~ou~d see~ that there lS hardly any organically polluted hqwd, wh_tOh cannot. be successfully dea.lb with by these recently dtsoovered frtends of humanity.

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SIX-YARD DIPPER DREDGE. CONSTRUCTED BY TH E BUCYRU COni PANY, OUTH 1\IIL\VAUKEE, " ''I· CON IN, U .. A.

(For Descriptio?t, see Page 595.)

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THE T'i\TIN-SCREW BATTLESHIP IC A s A I J~ F 0 R T I-I E IMPERI AL JAPANE SE NAVY.

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AGENTS FOR "ENGINEERING." AusTRIA, Vienna: Lehmann and Wentzel, Kartnen~raaee. OAPB TowN : Oordcn and Ootch. Eot.NBURGR: John Menzies and Oo., ~2, Han?ver:s~reet. Fa&'iOB, Paris : Boyvenu and OheT1llet, L1brame Etrang~re, 22,

Rue de la Banque ; M. Em. Terquem, 31 bia, Boulenrd Hauesmann. Also tor Advertisements, Agence Bans, 8, Place de la Bourse. (See next column.) .

GIJUIANY Berlin : .Messrs. A. Asher and Oo., 6bUnter den Lmden. ' Frankfurt-am-.Main : .Me~RJI"I. G. L. aube and Oo. (tor

Advertisements). Leipzig : F. A. Brockbaua. Mulhouae : H. Stuckelberier.

GLASGOW : WiUiam Love. IMDlA Calcutta: Thaoker, Spink, and Oo.

' Bombay : Thacker and Oo., Limited. ITALY : U. Hoepli, Milan, and ~ny post office. LIVBRPOOL : .Mrs. Ta.ylor, Landmg Stage. MANCHBSTBR: John Heywood, 143, Dennsgate. NoRWAY, Obristiania: Cammermeyers Bogbandel, Oarl Johans

Oa.de, 41 and 43. Nsw SouTH W AL&S, Sydney : Turner and Henderson, 16 and 18,

Hunter-street. Oordon and Ootch, George-street. QUBKNSLA.ND (SouTu){ Brisbane : Oordon and Ootoh.

(NORTHJ, TownsviUe : T. Willmett and Oo. RonDDAll : H. A. Krn~er and Son. . SOUTB AUSTRALIA, Adelaide: W. 0. R1gby. UNITKD STATBB, New York: W. H. Wiley, 43, East .19th·s~re~t.

Chicago : B. V. Holmes, 44, Lakes1de Buildin~. y 1oroRlA .Melbourne : Melville, Mullen, and Slade, 261/264, Oolline·

1treet.' Oordon and Ootch, Limited, Queen-street. -======

We be« to announce that American Subscriptions to ENGINE'8RING may now be addressed either direct to the Publisher, Mr. 0. R. JoBNSON at the offices of this Journal, Nos. 35 and 36, Bedford· street Strand London, W.O. , or to our accredited Agents for the United States' Mr. W. B. WILSV, 43, East 19th-street, New York, and Mr. H. V. BOLMES, 44, La.keside Building, Chicago. The prices of subscription (PO:Y~ble in advance) !or one ~ear are :. For thin (foreign) po.per ed1t1on1 ll. 1~. Od. , for thick (ordinary) paper edition 2Z. Os. 6d. ; or 1f rermtted to Agents, 9 dollars for thm and 10 d~llars for thick.

AMERICAN ADVERTISERS can obtain full particulars con· cerning our Advertisement Rates from Mr. WILLARD C. TYLKR, 9LS Morton Building, New York; and Mr. B. V. Bot.MJUJ, 44, Lakeside Building, Chicago.

ADVERTISEMENTS. The char,e tor advertisements is three shillinr for the first

four lines or under, and eightpence for each additional line. The line anrages seTe!l words. PM me~t mus~ B?OOtn~any all orders for single advertiSements, othenv1se theu msertion cannot be iUaro.nteed. Terms for displayed ad';ertisements ?n ~he wra.p~er and on the inside pages mo.y be obtamed on a.pphoahon. Senal advertisements will be inserted with all practicable re,ularity, bu\ ab!olute regularity cannot be guaranteed.

Advertisements intended for insertion in the cur· rent week's issue must be dellvered not later than 5 p.m. on Thursday. In consequence of the necessity for going to press early with a portion of the edition, alterations for standing Advertisements should be reoelved not later than 1 p.m. on Wednesday after· noon In each week.

SUBSCRIPTIONS, HOME AND FOREIGN. ENGINEERING can be supplied, direct from the Publisher,

post free for twelve months, at the following rates, payable in advance:-

For the United Kinrdom . . . . . . . . . . . . .£1 9 2 , all placet abroad :-

Thin paper copies........ .. £1 16 0 Thick , . . . . . . .. . . . . £2 0 6

All accounts are payable to "ENGINEERING," Limited. Obeques should be crossed " Union Bank, Oharing Oross Branch."

Post Office Orders payable at Bedlord·street, Strand, W.O. When fore ign Subscriptions are sent by Post Office Orders,

&<h'ice should be sent to the Publisher. ForeifO and Colonial Subscribers receiving incomplete copies

through newsagents are requested to communicate the fac~ to the Publilher, toiether with the a,ent's name and address.

Oftloe for Pnbllcation and Advertisements, Nos. 36 and 36, Bedtord·atreet, Strand, London, W.C.

We desire to oan the attention of our readers to the f~t that the above is our SOI·E Address, and that no connection ex:J.sts between this Journal and any other publloatioDJJ bearing somewhat stmtlar titles.

Tlueaumo ADD!I.BB&-BNGINEERING, LONDON. TILllPHONB NUliBBR- 3663 GePrard.

CONTENTS. PAGB PA&B

The Hotopp Syphon Looks Notes ..... .. .. ..... .... .. 600 on the Elbe-Trave Canal The Late Mr. Willia.m Duff (lllmtrated) . . . . . . . . . . . . 671 Bruce . . . . . . . . . . . . . . . . . . 691

Modem Field Artillery (Il- I Steel Rails . ... :. . . . . . . . . . . 691 lustrattd) .... . . . ... . ... 673 Road Looomot1ves (Illtt8.) 692

The institution of .Mech&· Yacht Measurement .. .... 693 nical En~oeers .... ...... 677 Th(Coal·Mining Industry . . 593

Paris Exhtbition Railways The Flip or Jump of a Gun (l llmtrated.) . . . . . . . . . . . . 677 or Rifte . . . . . . . . . . . . . . . . . . 693

The Japanese Battleship Notes from the United 11 Asahi " (llluttratecl) .. 681 States ......... .. ....... 69!

The Duddell Osoillograph Diagrams of Three Months' (fllmtrated) . . . . . . . . . . . . 682 Fluctuations in Prices

Notes from the .North... .. . 68~ of Metals .. .. .. .. . . . . . . .. 694 Notes from South Yorkshire 68-! Six-Yard Dipper Dredge(n· Notes from Cleveland and lmtrated) . . . . . . . . . . . . . . 695

the Northern Counttea . . 584 Industrial Notes . ... .... .. 696 Notes from the South-West 5 5 Road Locomotion (lUu1.) .. 697 Miscellanea .. . •...... . ...• • 685 The Physical Society ...... 600 Eleotrio Energy in Bulk.. . . 587 Launches and Trial Trips . . 600 The British Arsenic In· Graphical Constructions in

dustry .. .. .. .. . . .. .. .. .. 688 Engineering .. .. .. .. .. . . 601 Cor_npulsory Boiler lnsoea· I " Engineerin~' Patent Re-

t•on . . . . . . . . . . . . . . . . . . . . 689 I oord (IUttstrated). • • • . • • • 60S l'ith a f'wo · P(IIJo Ew.rraving oj THE TWIN· SCREW

BATTLESHIP cc A5ABI" FOR THE I:4fPERIAL JAPANESE NAVY.

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E N G I N E E R I N G. far wider in proportion to the traffic, and are much more easily restored, since they ar~ generally of

Advertisements from Germany should now be sent macadam or of granite pitchin_g. . In the c~se of through Messrs. G. L. Da.ube and Co., Frankflirt-am· wood-paving, and of as~hal~, 1t JS almos~ 1mpos­Maln, who have been appointed our Sole Agents for sible to insert a new stnp whtch shall be, 1n ever_y that country for Trade displayed Advertisements. way, equal to the origi_nal ~urface. B?t this Advertisements from France, Belgium, and Bol· d ifficulty does not obtain wtth other ktnds of land should be sent through the Agence Havas, r·oads. and there is no reason whatever why a 8, Place de la Bourse, Paris, our Sole Agents for ' · th

NOTICE TO CONTINENTAL ADVBRTISBR&.

those countries for stmnar Advertisements. local surveyor should not be able to tnsure . e --====----=----====~--====---=:=- perfect reinstatement of macadam and gran~te

RsADtNo OAsES.- Reading cnse8 tor containing twenty-six surfaces after the electric mains have been laid. numbers ot ENGINEERING may be had of the Publisher or of any The aeneral plan in such circumstances is to allow newsagent. Price 68. each. o

the local authority to make good the pavement,

NOTICES OF MEETINGS. SOCIP.rr OJo' E~OIN&KRS.-Monday, May 7, at the Royal United

Service Institution, Whitehall. A paper will be read, en~itled, " The Economical Disposal of Town Refuse," by Mr. Bnerley Denham Bealey. The chair will be taken at 7.30 p.m. precisely.

TliK INSTITUTION OF ELECTRIOAL ENGINBERS.-Thursday, 1\lay 10, rueetiog at the Society of Arts, John-street, W.O. •• A Friction· less Motor !leter," by 1\ir. S. Evershed, Assoc. 1\lember.

SOOJETY OF AR1'S.- Monday, May 7, at. 8 p.m. Cantor Lectures. 11 The Incandescent Gas Mantle and its Use," by Professor Vivian B. Lewes. Three Lectures. Lecture I. 11 Tbe History of lnoan· descent Gas Lighting." Tuesday, May 8, at 8 p.m. Applied Art Section. .. Art Metal Work," by Mr. Nelson Dawson Henry H. Ounynghame, O.B., will preside. Wednesday, May 9. at .8 p.m. Twentieth Ordinary Meeting. 11 Improvement of Our Roads," by Mr. A. Moresby White. Sir John Wolfe Barry, K.O.B., Chairman of the Council, will preside.

IRON AND STERL INSTITOTE.-Annual meeting, at the Institution of Oivil Engineers, Great George·street, Westminster, on Wed· nesday and Thursday, May 9 and 10, commencing each day at 10.30 a.m. On Wednesday the Council will present their report for the year 1 99. Tbe Bessemer Gold Medal for 1900 will be presented to Mr. Henri de Wendel, President of the Oomit~ des Forges de France. A selection of papers (4, 5, 6, and 9) will be read and discussed. On Thursday a selection of papers (1, 2, 3, 7, and 8) will be read and discussed. Tbe following is a. list of papers that are expected to be re1d and discussed : 1. .. On Ingots for Guu Tubes and Propeller Shafts," by Mr. F. J. R. Carrulla (Derby). 2. 11 On the .Manufacture and Application of Water· Gns,' by Mr. Oarl Dellwik (Stockholm). 3. 11 On the Equalisation of the Temperature of Hot Blast," by Mr. Lawrence Gjers and Mr. Joseph II. Harrison (Middlesbr'Jugh). 4. 11 On Blowing En~ines Driven by Orude Blast-FurnaceOa~," by Mr. AdolpheOreiner, Mem· ber of Council {Serain~, Belgium}. 5. " On the Solution Theory of Iron," by the Baron H. von JUptner (Donawitz, Austria}. 6 . .. On the U11e of Fluid Metal in the Open Hearth Furnace," by Mr. James Ri1ey, Vice-President (Stockton-on·Tees). 7. "On the Manganese Ores of Brar.il," by Mr. H. Kilburn Scott (Minas, Brazil). 8. "On the Utilisation of Blast-Furnace Slo~," by the Rttter Oecil von Schwarz (Li~ge). 9 ... On the Continuous Working of the Open· Hearth Furnace," by Mr. Beojamin Talbot (Pencoyd, Pennsyl· vania).

ENGINEERING. FRIDAY, MAY 4, 1900.

ELECTRIC ENERGY IN BULK. THE Committee appointed to inquire into the

Bills now before Parliament for the supply of elec­tric energy '' in bulk , commenced its sittings yesterday. These Bills were read a second time in the House of Commons some weeks ago, somewhat to the surprise of many who were interested in the subject, and who anticipated that the opposition of the municipalities would secure their rejection at that early stage. Fortunately Mr. Ritchie took a statesmanlike view of the subject, and advocated fuller inquiry before any final decision was adopted, and so, owing in great measure to his influence, defeat was avoided. It must not be supposed, however, that the danger is past, and that the measures in question will necessarily receive the Royal assent before the close of the Session. They are still on their trial, and immense exertions will be made by their opponents to secure their rejec­tion, if possible, and, failing that, to load them with so many liabilities and obligations that no one will undertake the responsibility of construct­ing the works which they authorise.

At a cursory glance it is difficult to understand why there should be so active and widespread an opposition against measures which seem to promise nothing but good to the districts which they will affect. The only point in which the urban and rural authorities will be injuriously affected by the operations of the companies supplying electric energy in bulk is in connection with the breaking and reinstatement of the roads. In this matter they, representing the inhabitants, will suffer some inconvenience, and in that respect they have the right to demand guarantees. This, however, is a very trifling matter. In London, with its enor­mous traffic, we manage to exist and conduct our business, in spite of the many interruptions of the streets due to the repair of gas, water, electric, and hydraulic mains, in addition to frequent re­newal of the surface, and what can be borne in the Metropolis can surely be endured in the smaller provincial towns. Their streets are

and charge the company with the expense, and under these condit ions the surveyor has a perfectly free hand, and if he does not make a good job of the work, it is his own fault.

The passing inconvenience of _h~ving t he roads opened is all that the local authorities have to fear. On the other hand, the ''electricity in bulk " schemes offer them very notable advantages. They will re­lieve the smaller municipalities of much of the anxiety of their present position under the Electric Lighting Act. Accordin~ to that they h~ve t~e right to set on foot electric supply works tn t~eir areas, even if other undertakers should be al1Xlous to execute the work. The councils enjoy the preference at the Doard of Trade, and can block their dist ricts against the entrance of private enter­prise. Great numbers of them have exercised this right, without, however, taking any steps to provide a supply themselves. There is, however, a limit to the time during which they can play the dog-in-the­manger, and many of them are now face to face with t he necessity of either taking action or allow­ing other persons to do. In not a few towns an electric lighting station is certain to make a loss for some years, and increase, instead of relievi~g, the rates, and such an occurrence is certain to bring odium to the council from a certain portion of the electorate. On the other hand, there are plenty of far-sighted commercial men who have sufficient con­fidence in the ultimate success of electric lighting to accept a temporary loss for the sake of future profits, and who will snatch at the opportunity if the councils let it pass. The dilemma is an awkward one for those who are eager to obtain the profits of municipal trading without under­taking its risks- a ' 'ery numerous class in our urban councils. The institution of a general supply in a district would, however, completely solve the difficulty in tnost cases. The council would buy what they wanted in bulk, at a rate which would be quite as low, i f not much lower, than that for which they could generate it for them­se! ves, and the only expense they would incur would be for mains, or about one-third that required for a complete equipment. 11he arrangement is an ideal one from their point of view. The r isks con­nected with electric lighting are at the generating station. There it is that fires and accidents occur. Not only does machinery depreciate, but, what is of more importance, it rapidly grows antiquated. Already many alternate- current stations have had to spend large sums in lower­ing the frequency of their supply, although their machines are comparati \?ely new ; and we are still far from finality in such matters. l\1ains, on the contrary, if of good quality and well la.id, are a very safe investment. Indeed, many of them have recently had their earning capacity increased fourfold by the increase of pressure from 100 to 200 volts, which we think is quite a unique experience in engineering. The town, therefore, that under­takes to distribute to its inhabitants a supply of electrical energy bought in bulk, tackles a problem in which there are practically no unknown quanti­ties, and at the same time indulges its ambition to enter into municipal trading.

One of the proposed companies, which will have ils field of operations in Durham, only asks powers to supply '' undertakers," municipal or private, leaving the entire work of distribution to them. The others, however, have wider aspirations, and, as a. rule, seek the right to enter into direct rela­tions with customers requiring power. To this extent they will invadt:} the domain of the munici­palities. It is, however, a Yery small matter. According to a paper read by Mr. Alfred H. Gib­bings, the electrical engineer to the city of Brad­ford, before the Northern Society of Electrical Engineers, on lVIarch 13, 1900, the number of elec­t~ic motor~ in use in various towns is only con­siderable m the cases of Manchester, Liverpool, Bradford, Edinburgh, Birmingham, and Nor-

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wich, just the places into which the "bulk" companies are certain not to gain admittance. In nearly every other case the demand for motors is a negligible quantity, and will remain so at t he prices at which a small electri~ station must de­mand t? assure itself against loss. The supply companies are founded in the expectation of in­augurating a new condition of affairs. With them t~e heavy costs of supervision and management w~l be vastly reduced, while labour-saving devices '~ill be employed to the ubmost. They will be situated where coal and water are cheap, and will lay themselves out from the commencement to obtain a good load factor. They will start on the assumption that they are going to do business in a wholesale fashion, with a comparatively small per­centage of profit on an immense output, and unless they realise this they will not be successful. 'fhey will, therefore, have to foster a demand in a way which is quite impossible for a municipality, and in doing this they must necessarily stimulate the industries of these districts in a remarkable way. The quack advertisement of a few years ago used to declare '' Electricity is Life, '' and certainly the presence of an immense electric supply company in a manufacturing district will quicken and vita­liee it in a way that nothing else can. It is a stock platform phrase that cheap power has made this country the workshop of the world, but it is a phrase which may easily mislP-ad. We have had cheap coal, and shall have it again when the present scarcity is over, but a great deal of the power we use is very dear. In the cotton mill and the steamship, and also in our locomotives, power is generated economically, but in most of our manufactories it costs far more than it should in the first instance, and then a great part of it is wasted in friction. The smaller the works the greater the waste. The supply company will give cheap power to all, and will put the jobbing mechanic who seizes his opportunity on a better footing than the large manufacturer who plods along the old way. Industries will spring up beside its mains, just as formerly they did along water courses. There are scores of valleys in Derbyshire and Yorkshire, which are dotted with the remains of mills built there in the past for the sake of the water p.:nver. When the steam engine became common these mills suffered from their position, and many of them were closed, the neighbourhood returning to its original pa~toral simplicity. We may possibly see a like migration of the smaller industries to the districts Rerved bysupplycompanies to the detriment of those which have not the same advantage.

The Bills before the Committee have, however, an interest to engineers quite apart from any eco­nomic advantages they promise to the districts concerned. Upon their passage, or rejection, de­pends the creation or loss of a great industry. If they succeed in becoming law, British engineers and manufacturers will have a new field opened to them-the transmission of power by electricity to considerable distances ; and in competing for orders in our colonies and elsewhere, t hey will be able to point to what they have done at home in evidence of their ability to design and construct such ma­chinery. At present they have to acknowled.ge, not without shame, that they have no practical experience in this branch of their art, and that what they know o_f it has been largely ~l~aned in America and Switzerland. Upon the dems10n of the Committee bang most important issues to the profession and the ~dustry. The matter in ques­tion is not the erect10n of three or four large gene­rating stations ; that is an affair of comparatively small moment. It is whether the scientific know­ledge the inventive skill, the manufacturing ability, and the commercial enterprise of this country are to be deliberately fettered in order that the counc~s of a number of third-rate towns may play at mun~­cipal trading and, if successful, may reduce their rates by 5 pe~ cent. That is the plain sta-tement of the case. Just as the famous Mr. Robins in selling a great London brewery told his audience he was not offering them so many tuns and vats, but the chance of growing ~ich beyond the. dreams of avarice, so the Committee are not settling whether electric stations shall be large or small, but whether Englishmen shall be allowed to obtain th~ir share of the wealth which other peoples are cre!l'hng. by fol­lowing this important branch of engine~rmg. It is worse than useless for us to have published .the views of many of the leading m. en m the l T :n~ted States on the subject of Amencan competitlOn,

E N G I N E E R I N G.

a~d ~or the Times to have sent its Special Com­nusswner across the Atlantic to spend weeks in examining steel and iron works to learn the secret of their success, if the Legislature is so blind to our danger as to regard the breaking of a few streets as of equal importance to the birth of a great industry.

The opposition to the Supply Bills will be strenu­ous, because so many people are interested in fomenting it. The paymaster-the general public :-has no voice in the matter, and so the restraining mfiuence of a cautious litigant is wanting. Town councillors find it agreeable to have their expenses paid to London in May, when there are so many things to be seen. Clerks to boards like conten­tious business, because it adds to their income and importance. Parliamentary agents and counsel live on other people's quarrels, and, generally, there is quite an army of men to whom an occa­sion of this kind is bread and cheese, and often champagne too. We are sorry, however, to see leading 1nembers of our own profession affording the support of their names to the opposition. We should have thought that at this great crisis their sympathies would have impelled them to exert their influence in aid of the movement, and that, unless bound by general retainers, they would have declined to assist their municipal friends in attacking their own brethren. We are quite aware how strong are the temptations in the opposite direction. There is a certain class of consulting engineer who would be pleased to see a miniature electric light station in every street, so long as he was called in to advise on it, and it would be expecting too much to think that such members of that branch of the profession will feel anything but hostility to the new schemes. It is, however, of those engineers who have already made their mark in the world, and who have reaped full sheaves in the harvest of success, that we are thinking. As men of science they must be interest.ed in the success of such an important forward step ; as men of light and leading they must desire to be in the van; and as prudent men they must welcome the opening up of a new department of practice. How comes it, then, that we find them providing ammunition for the forces of obstruction 1

THE BRITISH ARSENIC INDUSTRY. THERE is one branch, at any rate, of the Corn­

wall and Devon mining industry which has not felt the pinch of foreign competition, and this is the arsenic industry. True, the production of recent years has not attained to the figure of fifteen years ago, but against this must be put the fact that the prices ruling at present are considerably higher, and suggestive of a larger profit than was the case when the output was greater. The product of few branches of mining has been so much in the hands of merchants, who on several occasions have formed rings to regulate the price, a proceeding that can only be done with any degree of success where the total bulk of material dealt with is comparatively small. Arsenic itself cannot be considered a com­mercial article ; it is the white arsenious oxide which finds so much employment in the arts and manufactures, and it is this body which is meant by the term arsenic, as used in the present article. The main reason which prompts us to say a few words on this rather special industry at the present time is that a new mine, which is expected to add considerably to the amount now put yearly upon the market, has recently been opened in Eastern Cornwall, and any­thing which tends to provide the Co1·nish miner with work whereby he can maintain his household, and yet stay in the country, is not without iln­portance in these days of depopulation of rural districts. It is to be regretted, we may say, while on this point, that the expected revival of tin-mining has not come to pass, or, at least, only to an insigni­ficant extent, although the fltct that the metal now stands at 140l., instead of 60l., at which it was a year or two ago, certainly seemed to warrant the sanguine hopes of the native miners who looked to many of the 1nore recently abandoned mines being re-opened. However, we are trenching on ground which hardly concerns our present subject, and we hark back to arsenic, which, although it was at one time entirely, and still is, to a limited extent, merely a bye-product of tin-mining, is now worked entirely for itself in the case of one or two mines.

Especially does this remark apply to the noted

mine known as the Devon Great Consols which is located on the Devonshire bank of the Tamar which divides the county just named from Corn­wall. How a group of mining speculators ceased their operation when almost within touch of the great lode of copper ore which made the fortunes of the speculators of a later date, and how, when the copper ore gave out, a rich vein of arsenical pyrites or mundic, as it is locally called, was struck, are matters of history which border on the romantic. To-day the mine is in full swing, and turns out, in addition to an insignificant quantity of copper ore, an amount of ars~nic approximating to 2500 tons annua1ly, equalling the total yield of the other dozen or so of arsenic-producing mines in the two counties. To those who are not aware of the extent to which this body is used in the arts, the fact that from 6000 to 8000 tons have been annually produced by British mines may come somewhat in the light of a surprise ; that ignorance does prevail on the point is clear from the statement recently made by a chemical manufacturer in the North of England, that it was preposterous to talk of putting another 60 tons per month on the market. Whet her there is any good reason for open­ing out new arsenic property at the present time, is a matter on which we shall dispense with giving any decided opinion, but considering that in the seventies the substance was produced and sold at a profit for 7l. per ton, it certainly seems likely to be a profitable business provided that the present market price of 20l. per ton can be maintained. Probably, from the reason already mentioned, this will be the case, and we very much doubt if calico-printers, pottery manu­facturers, and the makers of green pigments, not to mention sundry other consumers (in a technical sense) of this chemical, will have the benefit of any substantial reduction in price, or will witness a shrinkage in values to those ruling twenty-five years ago, when two of the most prominent mines were selling in active opposition.

Although there is nothing of novelty to describe in the methods in present use for the manufacture of the arsenic from the ore, yet in view of the fact that the apparatus employed is peculiar to this business, and that, moreover, it is to be seen at work in but few districts of the world, it may not be superfluous to say a few words on the subject. The ore, which is variously called arsenical pyrites, mispickel, or mundic-the last being its common designation in Cornwall- is composed of arsenic, sulphur, and iron, and contains, when pure, 46 per cent. of arsenic. It is the only ore from which arsenic is obtained in England, though in Saxony and Silesia the substance is generally found in con­junction with cobalt. As for the process of obtain­ing the arsenic, it is a very simple one, consisting merely in calcining the ore and collecting the vola­tilised oxide in long flues. Naturally, the efHux of time has brought about changes in the details of operation, and the ·calcining furnace of an earlier date has been superst~ded by that in general use to­day, and which is known as the Oxland and Hock­ing calciner. This briefly may be described as a wrought·iron cylinder 30 ft. or so long, and about 3 ft. in diameter, with a firebrick lining. It inclines upwards from the furnace with which it is connected at its lower end, and is sup­ported upon rollers, w hioh cause it to revolve slowly. By this action, and aided by a number of projections in the tube, the crushed ore, which, after being mixed with coal, is fed in automatically, gets very thoroughly exposed to the furnace heat and rapidly becomes incandescent. The furnace is kept going night and day, Sundays included, until a sufficien t quantity of arsenic has collected in the flue, when it is cooled down, or in some cases connected with another flue. These flues, made usually of brick, are often of considerable length, and at intervals widen into chambers where the arsenic is deposited on projections. The length of the flues is necessitated not only from motives of economy in manufacture, but also from a desire to prevent the poisonous dust from passing out into the atmosphere. From 300 to 500 yards is a common length, though it is said that they have been made as Inuch as a mile long. From the chimney at the end nothing should exude but sulphurous acid, and tests which have been made show that this is practically the case. The deposit in the flues from the calciner is commonly known as arsenic soot, though its colour approximates more closely to that of flour than to the tint of coal soot. But for market it must be quite white, and

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therefore it undergoes tre~tment in the refining furnace, which in. England IS of th~ reverboratory type the verticalrron pots and upright condensers used' on the Continent not being found here. The arsenic soot is mixed with coke, and t he volatilised product which is now quite white- or should be so- is collected in flues similar to those of the firpt process. After this t here only remains the grmding and packing into small casks, ho_lding generally about 3 cwt., and t~e .stuff is ready f.or market. With regard to the mmmg of the mundtc, there is nothing about it which is not general to tin mining carried on at deep levels, though the stamps and huddles wl~ich f?rm a. necessarJ: part of the equipment of a tm mme are here dispensed with. To say a word or two more especially of the Devon Great Oonsols, as t he most important mine the drainage of the shafts, of which there are two ~r three situated on various eminences, is car­ried out by water-power, which is di~tributed by rods of considerable length connected w1th water-wheels in the valley, the whole arrangement being one of considerable ingenuity. As at Dolcoath and some other of the more important mines, the man-engine is still to be found, and the present generation of miners who have accustomed t hemselves to its use, would certainly not care to return to the toilsome ladder way. Accidents connected with the more modern means of locomotion are now of extreme rarity, though. in t~~ light of the dis~strou~ experi­ence of certam visitors to a Cornish mme, the ladder with all its toil, seems more suitable to the uninitiated than is the man-engine. The company possesses its own line of rail way from the mines to the guage, about four miles down the river ; and is thus more favourably situated a~ regards the carriage of coal and finished products than are several of the Cornish mines, such, for instance, as those at the Land's E nd. The new arsenic mine already referred to, is not particularly well situated as regards railway accommodation, a fact which may not be without effect upon its fortunes. That the question of carriage is of some import­ance, is clear from what one hears about t he pro­jected opening of certain closed mines as soon as some of the light railway schemes which are in the air come to maturity.

Our readers may naturally wonder what effect this well-known poison has upon t he workpeople who have to deal with it, and it is reassuring to be able to say that the strict Government regulations which are now in force have done very much to lessen an evil which in earlier times was cer tainly one of some prominence. Where every pre­caution is taken in the way of preventing t.he in­halation of the dust, and where the change of clothes and bath are rigidly adhered to, the men do not seem to suffer to any material degree, though, as may be noticed in most industries where un­pleasant, if not dangerous, processes have to be worked, the constitution of the individual workman is an important factor in the situation. In the operation of breaking and grinding the ore for the calciner's work, which is carried on to some extent by girls, there is nothing of a dangerous character, nor can it be said t hat the men in charge of the calciners experience any unpleasantness. It is in the periodical removal of the arsenic soot from the flues, and in the subsequent grinding and packing that the danger lies, and those engaged in t hese operations protect themselves by covering the face with fuller's earth, putting a cloth in their mouths, and by generally taking every precaution to prevent the irritant dust from settling on the skin, where, if allowed to lodge, it causes a peculiar eruption. The teeth, as in the case of the salt-cake furnacemen in the alkali districts, are peculiarly liable to attack, ~nd it is said that dental troubles are very common m the populous town of Camborne, where there are g.enerally traces of arsenic vapour in the air de­rlv~d !r?m. the roasting of the arsenical tin ores. ThlS mJunous effect of arsenic on the teeth is also home witness to by Englishmen who have held posts at the Rio Tin to copper mines at Huel va, whe~e, although the proportion of arsenic in the ore ~s but very small, it all passes into the air and not mto condensers, as is always the case in Corn­wa~. However, taking into consideration the pOisonous nature of the substance, it must be a mat~er for c?ngratulation that the industry is carr1ed on With such comparative immunity to th~se engaged in it, and it is to be hoped that by stnct enforcement of the Government regulations we sh~ll hear no more of men in the prime of life " rottmg away " as the resul t of their occupation.

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E N G I N E E R I N G . Although in Germany the manufacture of arsenic

is generally associated with that of other of the rarer metals, such as cobalt, in England this is not the case. True, 30 years ago a considerable amount of silver was extracted from the arsenical pyrites of Cornwall, but none of the metal is now pro­duced from this source, a remark which applies with similar force to cobalt, which under the name of smalt, finds a considerable application in the pott ery manufacture. An increasing quantity of arsenic in the form of realgar or the yellow sulphide is shipped from this country to South America in sheep-dip composition, for in spite of the increase in the use of carbolic acid for the purpose, the bulk of opinion inclines towards arsenic as being the most effective remedy for the parasitical troubles with which sheep are affiicted. On the other hand, we understand that the use of arsenical paints is on the decline, not so much because of their supposed dangerous properties in wall paper, &c., but rather because they have been superseded by something cheaper.

To conclude with a few remarks of a more or less statistical nature, it must be understood that the amount of arsenic mentioned above as being pro­duced in England is not by any means all utilised at home, much of it being exported, America being an important customer, as, so far, very little of this substance is produced across the water. It is not much beside the truth to say that England satisfies the world's requirements of arsenic, because we turn out a very much larger quantity than is yielded by the three or four other arsenic-producing centres of Europe put together. The fact that so much of the arsenic soot is obtained at a nominal expense as a bye·product of tin-mining is a point in favour of the decaying tin industry of Cornwall ; and at present, at any rate, it does not seem that the Straits or Tasmania are likely to enter into com­petit ion with us in the matter of arsenic, great as has been t he part they have played in deposing us from our once proud position as the foremost tin­producing country. We can, with safety, of course, speak only for the immediate future as regards pro­bable competition, for it mtist not be lost sight of that tin and arsenic are generally found in juxta­position; and if the important deposits, which are said to occur in the States come to be worked on the large scale, it is more t han probable that our shipments of the poisonous commodity across the water will show an appreciable decline at no very distant date.

COMPULSORY BOILER INSPECTION. IN E NGI·NEERING for March 30 and April 27 we

referred to the Bills for enforcing periodical boiler inspect ion, which have been brought in during the present session of Parliament by Mr. F en wick and Sir William Houldsworth. The third proposal in this direction is contained in the Factory Bill intro­duced by t he Home Secretary, in which one of the clauses reads as follows :

'' Every steam boiler used in a factory or work­shop, or in any place to which any of the provisions of the Factory Acts are applied by t he Act of 1895 or by this Act, must, whether separate or one of a range, (a) have attached to it a proper safety valve and a proper steam gauge and water gauge to show the pressure of steam and t he height of water in the boiler ; and (b) be cleaned out and examined in­ternally by a competent person at least once in every three months, and oftener if necessary; and (c) be examined internally and externally by a com­petent person once in every 12 months. Every such safety valve, steam gauge, and water gauge must be maintained in proper condition. The person making an examination in pursuance of this section must forthwith enter in the general register a certificate signed by him containing the prescribed particulars of the result of the examination. A factory or workshop in which there is a contraven­t-ion of this section shall be deemed not to be kept in conformity with the principal Act."

This clause may perhaps be considered as a step in the right direction in so far as it shows a desire on the part of the H ome Secretary to do something to reduce t he loss of life from boiler explosions. The utility of the proposal, however, is open to question; it merely touches the fringe of the matter, and its limited scope would seem to be its weakneas. The Bill applies to factories and workshops, and would, presumably, have its principal sphere of operation in the manu­facturing districts. In Lancashire and Yorkshire,

where factories abound, the boilers . on the wh?le are of a superior class, the constr~ctlon a~d equtp ­ment of fittings, generally speakmg, being up to date. It would be difficult, for instance, to find a boiler without a safety valve, a steam gauge, and a water gauge. In by far t~e gre~ter nm·~ber of cases the boilers are under mspectw~, mam}y. by the organised inspecting and insunng soe1et1e~. That is a point on which manufacturers and their managers are most particular. They have the boilers examined over all parts once a year, and occasionally under steam, by inspectors wh? are understood to be competent, and a repor t IS re­ceived after each visit . The yearly thorough ex­amination is considered to be sufficient for in­s.uring eafety, but in many instances the engine­men or attendants clean the boilers out at intervals, and make an examination, more or less complete, themselves. Special attention is paid to the fi t­tings, and the percentage of accidents due to de­fective safety valves, steam gauges, or water gauges, is small. The clause, therefore, appears to be somewhat unnecessary so far as factories and workshops are concerned, where, as a rule, its provisions are already observed. Even if we admitted that it is necessary and applicable, we may point out that no provision is made in any degree for securing the competency of the inspectors. There are always to be found amateur engineers who are anxious to pose as experts where the question of the inspection and safety of boilers is concerned, and the Board of Trade have on many occasions reported on explo­sions where the boilers had been examined by such persons, and, though dangerously defective, had been ignorantly pronounced to be perfectly safe. No declarat ion of competency, so far as we can see, has to be signed either by the boiler-owner or inspector, and we think that some decided modifi­cation would be necessary to make the clause as effective in this respect as could be desired.

If t he clause, as at present framed, became law, it might to a certain extent be use­ful, but the question arises whether it is wise to introduce piecemeal legislation on such an im­portant matter as the inspection of boilers 1 A law is required which will reach all sorts and con­ditions of works all over the country, and not simply factories and workshops, as defined in the Home Secretary's Bill. The clause would by no means touch the exact spot of the evil ; it would include boiler-owners at the specified works, but the careless owners, who are engaged in many other trades which we could mention, would be allowed to go on as before in their calm indifference to the state of their boilers, and the safety of their workpeople. If the Home Secretary in his wisdom could frame a measure in which the clause, now applied to certain factories and workshops, could be extended to include practically all the boilers in the country, useful legislation would, we think, be the result . A Bill, based on similar lines to the one referred to in detail by us last week, would probably meet the case. A remedy is needed for a wide area of disease, and legislation should by no means be confined to the narrow limits which the Home Secretary's Bill proposes.

Another measure now before Parliament is the '' Steam Engines and Boilers (Persons in Charge) Bill," brought in by Mr. Jonathan Samuel and other members. It differs from the three Bills to which we have referred, inasmuch as it is not a boiler inspection Bill, although its object, as stated by the promoters, is to save life. The propositien is that persons in charge of engines and boilers shall be examined and certified by the Home Secre­tary. I t '' does not a,pply to any boiler or engine used exclusiv~ly for domestic, agricultural, or farm­ing purposes, or to any boiler or engine used in t he service of Her Majesty, or to any boiler or engine used by a railway company, or to any boiler or engine used on board a steamship having a certifi­cate from the Board of Trade, or to any road trac­tion engine or steam roller."

The qualifications required are as follow : '' 1. A person taking charge or control of any

boiler or engine to which this Act applies, of 5 horse-power or upwards, or of any engine to which this Act applies, used for winding workmen or minerals up or down the shaft of a mine, must hold a first-class certificate or a special certificate of service under this Act.

'' 2. A person taking charge or control of any other boiler or engine to which this Act applies must be the holder either of such a certificate as

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aforesaid, or of a. second-class certificate under this Act.,

Applicants for certificates have to satisfy the Secr~tary of __ State as ~o character, knowledge, physical ability, expenence, &c. The entire management and control of the examination of can­didates as to subj ects, method of conductinO' the examination, time, place, &c., is left to the Secre­tary of State, and the expenses of carrying out the Act are to be defrayed out of moneys provided by Parliament.

Some three years ago (see ENGINEERING, March 5, 1897, page 317)westa.ted ourobjections to the general principles of this Bill, so that it will not be neces­sary to go over the whole ground on the present occa­sion. We 1na.y point out, however, primarily, that it is the boiler that needs exan1inationa.nd certification, and not the attendant. Year by year the propor­tion of explosions due to the neglect of attendants is very insignificant. Out of 152 explosions referred to in the reports by the Board of Trade issued under the Boiler Explosions Acts, for the two years ending June 30, 1898, and June 30, 1899, only 22 are ascribed to the ignorance or neglect of the attendant. Analysing these 22 explosions, we find that eight arose from shortness of water, four from the accumulation of scale, four from the im­pact of water, three from unequal strains induced by rapid cooling, &c., one from over-pressure con­sequent on overloading of the safety valve, one from overheating owing to the circulation of the water being checked by air in the pipes, and one from the vibration due to the breaking of the pro­peller shaft, the explosion consisting of the crack­ing of the main steam pipe on board a vessel. The explosions, therefore, due to actual oversight or ignorance on the part of the attendant, it will be seen were few in number. On the other hand, 120 of the explosions dealt with in the reports named, were attributed to deterioration by cor­rosion, defective design, undue working pressure, &c., which would seem to confirm the view that boilers and not attendants are, as a rule, at fault. Further, if boiler attendants were examined and certified, there would be no guarantee of permanent fitness or carefu]ness. Many explosions have occurred on board ship, where the boilers were in charge of certificated engineers ; but the fact that those engineers had passed an examination and obtained a certificate, did not necessarily lead them to exercise greater skill or care. The remedy for explosions is careful inspection. Would the passing of an examination formulated by the Secretary of State, and the obtaining of a certificate, enable the ca.ndidate to be a good h1spector ?. vVould it, indeed, make him in any way superi0r to the ordinarily intelligent and faithful attendant who probably. could not pass such an examina~ion, but yet is qu1te competent, as shown by experience, to perform his allott~d d_uties ?. Ag~in, the propo~i­tion that the examinatiOn of cand1dates shall be 1n the hands of the Secretary of State is open to criticism. The Department is not conversant with the technicalities of boiler inspection, and would probably have to depend for information mainly upon the Board of 'frade. The result, we fear, would be the introduction of a theoretical and book test as t he basis of examination. It is by no means necessary t hat a man in order to qualify as _a g~od boiler attendant should pass such an exam1nat10n as is proposed : in nine out of every t~n cases we doubt his ability to do so, and, even 1f he could, we cannot see that he would in any practical degree be better fitted for his position.

The Bill we consider is antagonistic to the interests of steam users. A fictitious Yalue would possibly as one result of its passing into law, be plac~d on t~e wages of boiler attendants, and this would ser1ously affect small employers. A dangerous power and an equally ~angerou~ mono­poly might in process of b~~ anse, and 1t would be unwise to place an add1t10nal burden on our already handicapped industries. Another point is that the employment of men who possessed certificates fron1 the Home Office .w?~ld tend to relieve the boiler-owner of respons1b1hty. In the case of an explosion he might urge that the atten­dant had been examined and certificated by the Home Office, t hat he had trusted him as a compe­tent man and t hat he alone was to blame. Fal~e confidenc~ might be inspired, and e~en lead 1n some instances to steam users neglectmg to adopt the principle of independent inspection which, up to now, has so safe-guarded th?ir boilers. A fur­ther objection to the measure IS that the cost of

E N G I N E E R I N G. the exa~ination of candidates is mainly to be borne by Parliament. This would 1nean introducing class legislation of a character to which, at present, we are strangers, and the taxpayer might protest against contributing to such an expenditure of public money.

On the other hand, if the Bill is, as its promoters affirm, so necessary, why are so many boilers left outside the pale of its operations ?. In the case of agricultural boilers, which frequently explode, the attendants, as a rule, are lamentably ignorant, and certainly neQd some education and training to fit them for their duties. We remember a case which occurred some years ago in which the boiler atten­dant, who was a farm labourer, sat upon the lever of the safety valve in order to increase the pressure, and was ultimately blown up with the boiler and killed. There have been other cases in which even the most elementary knowledge and care has been wanting on the part of the attendants. PerhapR it may be urged that this affords an argument in favour of the Bill. If so, we may ask, why ex€lude these men from receiving its benefits 1 If agricul­t ural boilers, among others, came under an efficient system of compulsory inspection, greater care would be exercised in their use, and attendants, whether good, bad, or indifferent, could not fail to derive ad vantage from the exan1inations made and the information given by the inspectors. Boilers at hotels and public buildings, many of which are to be found in our principal cities and towns, are also excluded from the Bill, as well as steam roller and traction engine boilers, all of which often work in populous districts and need careful attention.

We have only glanced at a few objections to the Bill, and others might be advanced if needful. In our opinion the Bill is totally unnecessary, and it could not fail to incur strong opposit ion on the part of steam users. Long experience shows con­clusively that the attendant is but seldom the guilty party in the case of an explosion, and we may repeat that it is the boiler which needs exami­nation. This point the Select Committee would do well to keep in mind when considering the general question of legislation. If the promoters of this Bill are anxious, as they doubtless are, to save life, we would suggest that they should go direct to the head and front of the offending, and inaugurate or support a proposal for the enforcement of periodical boiler inspection. They would be rendering a dis­tinct public service, and would be thereby more likely to attain their desired end of saving human life, than by agitating for the passing of a measure the effect of which would probably be to partially benefit a certain class of labour, but which, we fear, would be h~rassing to trade, and a constant source of trouble to boiler owners.

N 0 T E S. HIGH-TENSION ELECTRICAL EFJ.l'ECTS AT PARIS. A VERY interesting high-tension plant has been

arranged by M. D'Arsonval for obtaining the elec­trical effects, which are used to decorate the fagade of the Palais de l'Electricite at the Paris Exhibition. For the purpose in view it was necessary to be able to obtain at will either short or long sparks, which had moreover to be very brilliant and very noisy. The desired end was attained by the discharge of very powerful condensers charged to a high poten­tial by an alternating-current transformer. The transformer used is of 30-kilowatt capacity, and the alternator to which it is connected has a periodi­city of 42 cycles per second. The primary of the transformer consists of two sections, which can be coupled either in parallel or series. The high­tension circuit can be relied on to work up to 90,000 volts for prolonged periods, or to even higher voltages for shorter length of t ime. The condenser gave much trouble at the outset, since when glass was used as the insulator, even in a thickness of 5 millimetres (.196 in.), it was invariably pierced by the sparks, while ebonite, celluloid, and paraffined paper, proved equally ineffective. Finally, how­ever, micanite was adopted, and has resisted satis­factorily. The condenser, has in consequence, been built up of alternate layers of very thin tin-plates and sheets of micanite 2 millimetres (.079 in.) thick, and measuring 365 millimetres (14.37 in.) in length by 285 millimetres (11.22 in.) in breadth. The micanite in question, it 1nay be useful to add, is an American invention introduced some years back, and is made by cementing together very thin sheets of mica with gumlac, the whole being kept under heavy pressure while the cement is

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har~ening. The c?n~enser used is divided up into sect10ns, each cons1stmg of 20 plates of mica inter­leaved with the sheets of tinplate, and the capacity of each section is about one-hundreths of one micro­farad. The sections are finally completely im­mersed in paraffin oil. These condensers have given every satisfaction, · they do not heat, and being immersed in paraffin lose nothing by brush discharges. The spark is passed between two balls, the formation of a permanent arc being pre­vented by a blast of air or by the device due to M. d'Arsonal, of causing the balls to rotate by means of a small motor the rush of air being then sufficient to prevent the formation of an arc. The display with this arrangement is very striking and the noise is deafening. The length of spark obtained with the condensers, charged to 50,000 volts, is 18 to 20 centimetres (7.08 in. to 7.87 in.), but by suitably adjusting the speed of rotation of the two balls, the apparent length can be greatly increased, owing to the persistence of the vision, and in this way sparks appearing to be nearly 12 metres in length have been obtained. These sparks are really built up of many successive discharges, the balls having rotated into fresh position between each discharge and the next. Long sparks have, how­ever, been honestly obtained by electrical means by making use of a high-tension transformer, through the primary of which is passed the current from the condensers already described, and with one of these, sparks 80 centimetres (31.49 in.) long were obtained, and with the more powerful trans­former now being made this length will be still further increased.

SEW AOE PURIFICATION PROBLEMS. We believe that it is by no means generally

known that the fact that sewage could be puri­fied by intermittent sand filtration was brought before the Rivers Pollution Commission in 1870 by the late Dr. Frankland, who based his statements on laboratory experiments, and held that the system would provide the r eadiest method of solving the problem of sewage disposal. 'Vith the exception of certain works carried out by Mr. Bailey Denton, the discovery was, however, almost completely ignored, probably owing to the im­possibility at that date of recognising the mecha­nism by which the purification was effected. The scientific mind is slow to accept processes it is un­able to explain, and from this point of view it is possible that a less able commission would have been more easily impressed with the advantages of the system proposed. At that date, though bacterial life was known to exist, its importance was but faintly grasped even by leading lights of the scientific world. In fact, the existence of such organisms had been established mainly by indirect reasoning, and some eminent men, such as Dr. Bastian, were prepared to maintain that they were spontaneously generated in putrefying matter. Indeed, the earlier attempts at sewage disposal, based upon the scien­tific know ledge of the time, generally ·succeeded in making matters worse, and purely empirical processes, unguided by reason or scientific know­ledge, were generally more satisfactory in practice. The true nature of the process of putrefaction being ID:isunderstood, disinfectants were added, with the result that whilst an eftiuent free from offensive odour might be discharged into a waterway, the process of putrefaction was meJ;"ely postponed, and the nuisance was transferred from the outfall works to the streams some miles below. Though the significance of Dr. Frankland's work was not grasped at the time, yet the requirement that sewage should be passed through land before being dis­charged into rivers serving as sources of water supply, was effective in putting an end to these attempts of well-meaning chemists to cheat Nature; but the very large area of land required for broad irrigation works was a very serious matter to many of the towns concerned. The great possibilities of the system of intermittent filtration for the disposal of sewage were, however, again brought prominently forward by the Massachusetts State Board of Health in 1889. In the meantime the science of bacteriology had taken immense strides, following l{och's inven­tion of a method of estimating their number and character by culture on gelatine plates, and the time had accordingly arrived when some rationalconcep­tion could be formed of the true mechanism of the extraordinary degree of purification which experi­ment showed could be effected by passing sewage through well aerated filters. Experiments made at Barking by Mr. Dibdin led to the adoption of the very

interesting sewage filtration p!ant at Sutton! where 't was found that greater effiCiency was obtamed by dividing up the given filtering area into two sets of filters, through ~hie~ the sewage was passed in succession const1tutmg the so-called double con­tact syste'm. ~his was foll~wed by the very important invenhon of the sept1c tank, the first of which was constructed .by ~r. Oameron at Exeter. The sewage is kept ~n this tank, excluded frot~ light and air for a period of some hours before 1t is allowed to' pass on to the filter~, and it is found that in this way the rate of filtratwn can be greatly increased, and tha~ owing to t~e solution of ~u~h of the solid orgaruc matter whilst the sewage IS In the tank the sludge question is practically solved. At Mandhester a system combining those in use at Exeter and Sutton is being adopted.

THE PRoTECTIVE PowER OF PAINTS.

IN a paper rece1_1tly read bef?re the Newcastle section of the SoCiety of Chemical Industry, 1\lr. Harry Smith, F .. I. C., describes a series ?f very interesting experu!lents upo1_1 the comp~rative .pro­tective powers of different paints as applied to non­work. Three series of experiments were made. In the first series a method originating with Mr. Max Toltze was employed; a number of iron dishes, 5 in. across and about ! in. deep, were cleaned and carefully painted with two coats of the paint to be tested. These dishes were then filled with water, which was allowed to completely evaporate at the ordinary tempera~ure of the labo~atory, af~er wh~ch the dish was agam filled up ; this operatwn bemg repeated six times in the cou1·se of the six months over which the experiments extended. The paints used were prepared by grinding the pigments with linseed oil on granite rollers to a stiff paste, which was then thinned with best quality boiled linseed oil- itself capable of drying in seven hours to a hard film when painted on to a glass plate. Thus tested, the only paints which re­mained practically unaffected were red lead or orange lead paints, some of which, however, such as the "vermilionette" and the scarlet red paints, contained also a certain proport ion of aniline colours; whilst two of the red-lead paints contained, in the one case 45 per cent., and in the other 66 per cent., of barytes. All the other dishes were more or less rusted, the order of merit of the better paints being as follows : 1. Zinc white. 2. Equal parts zinc white and barytes. 3. Zinc w bite 3 parts, barytes 7 parts. 4. Lithopone (a mixture of zinc sulphide, zinc oxide, and barium sulphate). 5. Pure white lead. 6. White lead, 5.37 parts, barytes 4.03 parts. 7. White lead 5.05 parts, barytes 4.21 parts. All the other paints, 36 in number, proved very inefficient, the first dish to show signs of rust being that painted simply with linseed oil. In the second series of experiments a number of painted iron plates were exposed to the weather for a twelvemonth, and with the single ex­ception of the plate painted simply with linseed oil, all withstood the test remarkably well. In the third series of tests, strips of iron were painted, and when the second coat was quite dry these strips were placed in wide-mouthed glass bottles, which were then nearly filled with water, and allowed to stand. The bottles were not closed, but the con­tents were protected from dirt by standing them under a shelf, there being about ! in. of space be­tween the top of the bottles and the underside of this shelf. The bottles were left untouched for three months. Some of the plates were sensibly affected within seven days; but those which successfully withstood the shallow-dish test also resisted this one most successfully. The fact that paints containing such large proportions of barytes, as some of the lead paints noted above, gave such excellent results, is of much interest, as it goes to show that this material can hardly be co~sidered as a mere adulterant. In fact, one pamt made up only of barytes and linseed oil gave better results than an oxide of iron paint. Mr. Smith refers with approval to the methods adopted in painting the Forth Bridge. All plates and bars for tha.t structure were cleaned with st~el scrap~rs and wire brushes, and then coated Wlth . hot lmseed .oil. As soon as possible after erectiOn they received two coats of red-lead paint ~hich ~ere subsequently followed by two coats of 1ron. onde. The life of the paint on the upper portiOns exposed to the weather is found to be about three years ; but it must be added that the paint is then still in good condition, and on less llllporliant bridges would by many engineers be

E N G I N E E R I N G.

allowed to pass for several years longer. Experi­ence shows, however, that in s uch cases the metal is liable to be deeply pitted. The paint inside the tubes of the }i'orth Bridge is as perfect as when first applied twelve years ago. The parts of the bridge most subject to rust are near the water, where the underside of the girders get sprayed with salt. The rust ing commences on the rivet­heads and the edges of the plates. These portions of the bridge are cleaned and repainted every year. The work is in charge of Mr. A. Hunter, who has supplied Mr. Smith with the above particulars .

THE LATE MR. WILLIAM DUFF BRUCE. AN engineer who contributed in no small measure

to the prosperity of our great Indian dependency, since it suffered a;ll the calamity of the Mutiny, has just passed away in the person of Mr. William Duff Bruce, of whose death, on the 24th ult., we heard with regret, for he was yet comparatively young, although he had done a life's measure of good work. He was born on April 10, 1839, and had thus just completed his 61 years. Although born in Ireland, where his father had temporarily taken a country estate- at Brooklawn, in County Leitrim - he came of an old Banffshire family, as is almost suggested by his name. When nine years of age he was sent to St. Andrews to be educated, and returned t o Ireland in 1854 to serYe apprenticeship with Messrs. Thomas Grendon and Co., Drogbeda; and during the five years he went through the shops and drawing office, and was, towards the end of his time, engaged in the design and erection of locomotives, marine and land engines, iron bridges, and mill work. J\IIr. Bruce followed up this practical training by taking the engineering course at St. Andrews University, with the special intention of competing for a place in the Indian Public Works Department, at the examinations instituted about this time by Lord Stanley of Alderley, the Secretary of State for India. He took second place in the exami­nation of July, 1860, and proceeded at once to India, where he continued until 1887, doing, as we have said, most effective work towards the material advancement of India.

The first six months of his time walL spent in Roorkee College, learning the language, and becoming acquainted with essentially Indian problems. His first appointment was assistant engineer in the Cawnpore military division, with special charge of the Futtegarh district ; and it is interesting to note that his first work was the erection of a memorial church there to commemorate those who had fallen during the Mutiny. In 1863 he was transferred to Oudh, being appointed assistant to the chief engineer and secretary to the Chief Commissioner in Lucknow; and two years later he became municipal engineer at Lucknow, and during his residence there recon­structed the drainage system, and built a bridge with three 80-ft. spans in brickwork across the Goomtee Rhrer. It was at this early period of his career that he became a member of the Institution of Mechanical Engineers. When at Lucknow, too, he designed and built a fine series of double-storied barracks.

Mr. Bruce's next move in the service was to Cal· cutta, where probably his most effective work was done. Many of the fine public buildings in that town are his design-the High Church, the Telegraph-office, the High Court, the Museum, &c., but his reconstruc­tion of the harbour is the most notable improvement effected. In 1870 he was promoted to the charge of the works, at a time when new Commissioners were constituted on the same general lines as the Mersey Board, and of this body Mr. Bruce became vice-chair­man and chief engineer. In 1873 the river works be­tween the town of Calcutta and the sea also came under the jurisdiction of the Calcutta Port Commis­sioners, and Mr. Bruce was called upon to recon­struct lighthouses, lightships, and to improve the channel generally. 1n 1884 his scheme for the exten­sive dock system was approved ; and this work, cost­ing 2! millions, he carried to a successful issue. These works need not be dealt with at any length, they were described at the time in ENGINEERING; and Mr. Bruce contributed a paper on them to the Institution of Civil Engineers, for which he was awarded a Telford Medal. He had joined the Insti­tution in 1873.

Mr. Bruce continued in Calcutta until1887, when on retirement he was presented with a valuable ser­vice of plate by the officers and servants of the Com­mission; but even after his return to London he held the appointment of consulting engineer to the Port Commissioners, and his memory will be cherished in the Indian city alike for his splendid work as well as for his genial society. In 1887, Mr. Bruce com­menced business in London as a consulting engineer, and later assumed as partner Mr. J. Angus, and since then the firm have done important work. Mr. Bruce was consulting engineer to the Delhi-Umballa-Kalka Railway and to the Assam-Bengalline, concessions for both of which he obtained from the Secretary of State

59 I

for India. He laboured long and unceasingly towards the establishment of iron works in India, and the re­sults aro now being realised and will continue. t o flow from his efforts. He was also connected With the Rio Tinto mines, as a technical adviser, director, and deputy-chairman. Mr. Bru~e had a very wide cir~le of friends, for although he d1d not take a very active part in the public proceedings of the institutions asso­ciated with the profession, he liked social life, and was s. charming companion.

STEEL RAILS. A•r the ordinary meeting of the Institution of Civil

Engineers, held on Tuesday, April 10, Sir Douglas F ox, PreAident, in the chair, two pa~rs were read.

In the first of these, on " The Development of the Manufacture and Use of Rails in Great Britain," by Sir Ieaao Lowthian, Bell, Bart., LL.D., F.R.S., M. Inst. C.E., the author traced the history of the development of wrought iron and steel manufacture, with particular reference to its employment for rolling into rails. Com­parison was made of the relative loss of weight of iron and steel rails due to wear in use. Experiments made by the author, in order to study the circumstances which influence the comparative rapidity of the disappearance of carbon and phosphorus from the liquefied metal, were then re. £erred to. With regard to the properties of Bessemer steel, the author commented on the irregularity in the strength of rails produced from this metal.

Results of experimental tests of rails, by fra-cture under a falling weight, were given. Rails rolled from the upper middle, and lower part of the ingot were compared in this manner, and also by chemical analysis. The results of an experimental investigation of the deflection of rails at various speeds of the train were given. These tended to prove thab the deflection, and therefore the pressure on the rail, diminished as the speed increased. The author referred to the extreme brittleness of rails after use, and also to the grinding effecb of traffic on the rails. The molecular change brought about in rails by use, and the effects of the presence of phosphorus and silicon in the material · of rails, were touched upon. In conclusion, the author remarked that the durability of rails mannfactured by the basic process had proved equal to that of steel rails manufactured from h~matite ore.

In the second pa:Q_er, on " The Wear of Steel Rails in Tunnels," by Mr. Thomas Andrews, F.R.S., M. Inst. C. E., the author investigated the effects of the deteriorat­ing influences peculiar to rails laid in tunnels. Among these were the increased corrosion of the surface of the rail, due to the action of moist chemical vapours, and the increased chemical action of the ballast on the foot of the rail ; the ballast, on account of its porous nature, absorbed the chemical vapours, and hence acted with increased deteriorative force on the rails.

The author had made a careful examination of a rail which had done its life's work in such a situation. The results of this examination were given, with reference to the mechanical, chemical, and phy:sical changes which the rail had under~one during its hfe in the tunnel. The rail had been latd in a tunnel for seven years, on a straight piece of road having a falling gradient of 1 in 90, and it had carried the main-line traffic during this time without fracture. The tunnel was about 1000 yards in length, and it was situated fairly near the sea-coast. It lay in a direction nearly north and sou~h. This fact was pointed out, as the author had observed'indications that magnetis­ation E\xerted an influence tending to increase the cor­rosibility of steel in certain solutions.

The rail, which originally weighed 84lb. per yard, had lost weight at the rate of 2.8 lb. per yard per annum, and on the face the rail had worn down to the extent of i in. Tha chemical analysis showed that sulphur was present in considerable excess, but otherwise the general com­position of the steel was excellent. The physical tests showed a very good result, the strength of the metal bein~ normal, and an elongation of 27 per cen b. being obtamed. To ohviate the excessive wear of rails in tunnels, the author advocated the employment of a heavier section of rail, with a wider wearing surface. He also expressed the opinion that, as a general rule, rails in tunnels should only be allowed to remain in the l>ermanent ~ay for OI~e-half (or in some cases only. one-thud) of the time that IS usually allowed for the ordmary use outside tunnels.

SOROOABA.-Steps are being taken to provide Sorocaba with a good supply of water. The water is to be taken from the Valtarantim, and is to be raised to a certain height by means of turbines.

HAMBURG.-The entrances of shipping at this port in the first three months of this year were 1, 778 400 tons as compared with 1,731,640 tons in the corr~sponding period of 1899. The clearances of shipping from the port in the first quarter of this year were 1,803,133 tons as compared with 1,691,531 tons in the first quarter of 1899.

- --CoAL.-The quantity of coal exported from the United

Kingdom in the firat three months of this year was 10,274,745 tons, as compared with 9,691,596 tons in the corresponding period of 1899, and 8,508,542 tons in the corresponding period of 189~. Th~ exports of coal to France have been largely mcreasmg of late having amounted to March 31 this year to 2,200 06i tons as c~mpared with 1,81~,813 tons an~ 1,579,421' tons respec­tively. The .quantity of coal shtpped in the first three mon.ths of thiS year for the use of steamers engaged in foreign trade was 2,939,410t6ns, as compared with 2 867 304 tons and 2,642,283 tons, respectively. , '

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ROAD LOOOMOTIVES. To THE EDITOR OF ENGINEERING.

S~~~-Y: our very interesting and instruoti ve remarks on the Wetghtof Motor Wagons ,on page355amte, have in­duced me to send you a few observations on the limit to which your propo~ed increase of weight should be allowed to extend. And also to call attention to the fact that there ar~ other poin~s of road locomotive legislation, besides thts, that require readjustment; and which it may be useful to h~ve get;lerally stated, even although there may !lot be. any tmmed.tate prospect of obtaining the relief that ts obv10usly requtred.

In the first place, I think that some further reference should be made to t~e all-important point of the neces­sary amo';ln~ of bearmg surface for the driving wheels ; ~s th~ extstu~g motor wagon, with its low narrow wheels, 18 qu1te unsuttable for those "rural districts, into which at pre3ent it. seems so anxious to wander. And in order to have a suttable and universal basis of comparison it ~s evident that the diameter of a wheel must be taken 1nto account, as well as its breadth · for a ton 0:1 a 3-ft. wheel 3 in. wide, is obviously twice as severe o~ a road, ~s ~he same weight on a 6-ft. wheel 3 in. w1de.. A~?. tt 18, therefore, quite indefinite to merely men~10n . mches of. breadth per ton,, without this q ua.hfioa.t10n, by whwh the practical results can be so largely varied. And so as a general statement we may ta.ke it that .the breadth ?f a ~oad wheel, per to~ of load, must vary mversely to tts dtameter in order that the pressure on t~e supJ>orting surface ~ay, on a soft road, ~hua be equal~ed. But on a hard road, this attempt to Increase bearmg surface by mean~ of increased width of wheel, very soon attains a hmit beyond which it is useless to go ; for the reason that a common road does not make any ~pproa.oh a.t ~ll to being a prue plane, but invariably conststs of a senes of very trregula.r projections and hollows, formed on a surface which is curved and which slopes rapidly awa.y in a very uncertain man'ner to ea.oh side of its course. '

The a~oJm_pa.n:ying Fig. 1 is an illustration of this, from whtoh tb Wlll be seen that no amount of increase of wi?th, will ever_prevent ~he projection on the road from bemg crushed, tf the wetght on the wheel is sufficiently gre_at. And the same applies to Fig. 2, where, if the wetght ts great enough, the inner edge will disintegrate the surface, whatever the breadth of the wheel will be. If, however, a flexible tyre be used, as in Fig. 3, capable of a large amount of transverse, as well as other adjust­ments, these defects can be eliminated. However, with rigid wheels, on a hard road, there is a moderate breadth for any diameter, bsyond which it is practically useless to f{O.

With rigid tyres then, on a hard road, the only way to increase tlie bearing surface is to enlarge the diameter ; a9 it is evident that 3 tons on the wheel in Fig. 2, will dis­tress the road twice a.s much, if the wheel is only 3 ft. in diameter, as it would if it wer~ 6ft. high, even although we make the small wheel twice as wide a.s the larger. This study of the question of road wheels might have a large amount of time devoted to it, which, however, cannot here be given. And so it will have to suffice to merely say that, for heavy work, the present motor wagon system of driving by a low wheel, is very objectionable for either ha.rd or soft roads, as on a. hard road, it concentrates all the weight and driving strain on one little portion of the surface, which it disintegrates ; while on a. soft road, it sinks more readily than one bhab is larger, rolls with an increased resistance, and more easily leads to floundering in the mire, from which it can only be extricated with increased difficulty.

In order to bake cognisance of this means of driving by means of heavily weighted low wheels, ibis probable that if the 3-ton limit should be raised, that then the motor wagon mA.ker will bs thrown upon some such provision as that in the 1878 Act, which states : "A locomotive shall have the tyres of the drivin~ wheels thereof, not less than 2 in. in width for every ton m weight, unless the diameter of such wheels shall exceed 5 ft,, when the width of the tyres may be reduced in the same proportion as the dia­meter of the wheels is increased." This Act did nob con­template driving wheels smaller than 5 ft., but as such have come into use for heavy weights, the provision that the wheels may be narrowed for increases of diameter, will probably in the future be accompanied by the condi­tion that they must be a.lso proportionately widened, for wheels smaller than this size. So that the 5-ft. wheel would thus become the standard diameter, at which to reckon the prescribed minimum width of tyres.

Turning now to actual practice with traction engines, and always differentiating for any variation from a stan­dard diameter of 5 ft., as just stated- we find that this width of 2 in. per ton, is alwayo very largely exceeded; the minimum width for any kind of driving wheel being 4 in., while many have 5 in., and others even more. The width of driving wheels, 4ft. 6 in. in diameter, on the first of Thomson's rubber-wheeled road steamers, which was shown in ENGINEERING for December, 1867, page 579, and which was the firat illustration of theee engines that ever appeared-was 5 in. f<?r each ton. While a v~ry common width for such engmes made afterwards, w1th 5-ft. wheels, was 6 in. per ton; from which we see that their ability to pass over even. th.e sand o~ the seashor~, was quite as much due to theu h~ht loadmg as to their possession of the rubber tyres, which, of course, could not become flattened to give increased bearing a.rea, unless they rested on a surface sufficiently hard and firm to deform them. Moreover, the constant practice with ordi­nary traction engines is to co.n~inually go on increas~ng the bearing surface of. the drJ.vmg ~heels _by et;llargmg their diameters, by whtch means thetr relat1 ve wtd th per ton can be. greatly advanced over ~ny of th~ figures given; and 1b may be ta,ken t~t the mmunum w1dth of ~

E N G I N E E R I N G.

traction engine. driving w~eel. with ~he or4inary rigid tyre, ab 5 ft.-diameter, wtll, m the tmmedtate future not ~ le..~ than 6 in. per ton of load for soft ground: And 1t wtll always be sought to obtain this proportion fr?m an increase of diameter, rather than from that of wtdth.

Taking now the motor wagons tested at Li verpoollast year, we find that the widths of the driving wheels per ton.of load-on the standard 5-ft. basis of computation­varied between only 1.8 in. and 1.1 in. for a light and heavy wagon respectively. And we are therefore at once struck by the fact of the utter inadequacy of the carriages for soft ~ound ; as not one of them has even one-half of the t~&<~t10n eng\ne ~inimum all~wanoe. And yet how easy tt ts for even thiS latter engme to get into trouble when it leaves the terra firms. of the high road to pursue its ad ventures in rural districts ! And how then can the existing type of motor wagon, with its little narrow wheels, hope to bring that relief to the " distressed far~er, :' for which he is suppos~d to be waitin~ until its arrtvalm the farmyard? For agr10ultural work, It is quite evident that the present design will have to be re-oast with muoh larger and wider wheels ; and for this a liberal increase of wetght will ha.ve to be provided. ~n order to ascertain next what this p~ospective wei~ht

mtght amount to, we commence by takmg the followmg statement from the last report of the Liverpool Self-Pro­pelled Traffic Association : " Four tons of load, carried on the legal tare of 3 tons, at the legal speed of 5 miles a.n hour, is the maximum performance that has so far been obtained by a. four-wheeled vehicle." And then further as to future requirements, "self-contained vehicles capable of transporting regularly loads of from 6 to 8 tons at from 4 to 5 miles an hour, and up to 10 or 12 tons ab red uoed speeds, would shortly be available were a 4-ton tare sanctioned." That is, tha.t the present tare of 3 tons only allows 4 tons of useful load to be carried ; while if 4 tons of tare should be allowed, that a paying load of even 12 tons would then become practically obtainable. But is not that an obviously incorrect conclusion to be put forward by the writers ? For in this latter case the weight of material would have to be very largely increased; the extra amount in the wheels, springs, a.nd axles alone, being considerable. For the driving axle would have to

8. .1. . -2.

carry 14 tons, which would require wheels, only 39 in. high, to be 21 in. wide, on the basis of 2 in. per ton for a 5-ft. wheel, while the front wheels at 33 in. high would be 11 in. wide ; which would lead to formidable propor­tions in the Akermann st€ering axle and gear. These dimensions might be taken for ordinary macadam, hub if we attempt to apply the minimum traction engine width of 4 in. we then find that each driving wheel would actually have to be 42 in. wide. From which we a.t once see that the proposal to carry 14 tons on 39-in. wheels, is, for soft ground, impracticable; and that wheels very much higher than this would have to be used. But how­ever we modify the arrangement, how can one single extra ton of material be sufficient to comfortably cover all the possible contingencies of increasing the present load three times? Surely even one-half of the load to be carried, or 6 tons of material, would be required to pre­venb the designer of a 12-ton wagon from again getting into trouble with his proportions and weights, and so calling out afresh for the proverbial " more."

However, another matter that the writer considers of more pressing importance than increasing the weight of motor wagons, is that of allowing large omnibuses to run on the roads a.b useful speeds. For the motor wagon, up to 3 tons, has at J:>resenb all the liberty that is required for it; and in addttion to that, it could, if desired, be at once put to work under the 1898 Act, up to any size and weight that would be practicable. But the large motor omnibus cannot be put mto any kind of useful work at all on account of its absolutely necessary requirements of weight and speed. In regard to this, it may perhaps be said that it has the same opportunity under the 3-ton limit as the wagon, but this 1s nob the case. For a 40-passenger omnibus mus t of necessity be very much heavier than the existing wagons. It requires a much longer frame; a b_ody having heavy gla~3 win~ows, outside seats, and ascensiOn ladders ; and a b01ler twtce as power­ful as that of. th~ wagon. So that if the wa~o~ can. only jus t keep wtthm the 3 tons at preseJ?-t, tt .18 evtdent that the omnibus musb go far over th1s wetgh t. And to avoid any kind of risk with such a. larg:e number of people, it must also be a very subs tant1al ptece of work, considerably different in pattern from that suitable for a goods wagon. And, _in ~d~tion to all t~is~ eyen if it were possible to get tt wtthm the 3-~n hmtt, tt WO';lld still only be allowed to run a.t 5 miles an hour, which would be useless for passengers ; so that the omnibus is worse off than the wagon. The 1896 Act makes no dis­tinction at aJl between various kinds of traffic. It evi­dently never intended to provide for the transit of goods; it is merely by a fortunate accident that the "motor wagQn " has been l\ble to find s4elter within it~ fold; and

I ~

it also never contemplated the working of large omni buses. It was simply passed to promote the use of what may be styled p~eas~re carriages, a.nd the idea of any larg~-sca.le ~rade m . etther goods or .Passengers, is quite out:~ude .of .tts provmce; as is suffimently shown by its wetght hmtt of 3 tons.

And so here is, in itsel£1 a very large field of engineering usefu.lness, into '!hich it IS impossible to enter, on a com­mermal scale, w1thout contravening the law. And yet there would be a great opening for such omnibuse~ for many places in which tram ways could never be made to pay, and where they would offer advantages fairly com­parab~e with those given by even the most advanced electno tramway. ~or, as reg~rds comfort, the omnibus ~ould be made wtth very w1de wood tyres, running dueotly on the ground-a system which it has been proved makes, e':en at 20 miles an hour, a reasonable approach to a contmuous wood pavement, while the seats inside and oub woul4 be .luxuriously upholstered. As regards speod1 an ommbus IS nob delayed by traffic to anything hke tne same extent as a. tramway car frequently is · and on a. clear road it would run at any speed allowed by la.w. And as regards cheap fares, the omnibus could be pub to work f~r a. very small fraction of the money that would be sunk m the tramway; and hence, even in outlying d~tricts, could always well afford to run at truly popular priCes. And yet the only objection, of any kind whab­ev('r, to all th1s _possible enterprise and work, lies in the mistaken limitatiOns of a hastily passed la.w.

.c,1 minor po!nt that ~lso requires attention is the regu­lation as to w1dth. W1th horse-drawn wagons and onmi­buses, measured over the naves of the wheels, this fre­quently extends to 8ft., and a road locomotive may go up to 9ft.; while, however, the Local Government Board prescribe only 6 fb. 6 in. This should be increased to acco?lmodate the wide wheels of prospective larger carriages, and we may suppose, would be allowed for, if a new Act should ever be passed.

However,_ although ibis quite feasible, and, ~ndeed, an extremely stmple matter, to make a self-contamed omni­bus to carry even fifty passengers, it would yet probably be going beyond the supporting capabilities of ordinary common road surfaces, to make a. self-contained wagon, with a fla.t platform floor, and therefore with low wheels, to carry a load so great as 12 tons, even withoufl raising the question of the width of these wheels, and of its con­sequent ability to leave the high road. For while the omnibus, loaded, would always be well within 10 tons, the wagon in the gross, would actually weigh about 20 tons, with 14 tons on a. single pair of small driving wheels. This proportion of weight might, of course, be altered by dividmg the 20 tons equally amongst the four wheels; but this would lead to a lack of a{ihesion, which, with the ordinary proportion Gf loading, is even now deficient. The Liverpool judges expressing their desire for much more than the usually existing amount, say : " The importance of placing as much as possible of the weight of the vehicle upon the driving axle cannot be magnified, and is seriously commanded to the immediate attention of manufacturers. No vehicle has yet come before the judges which would not, under some conditions, have been more efficient had more adhesion been available." And so they are thus presumably asking for at least 15 tons to be placed on the two low wheels of the prospec­tive wagon, which would evidently thus become a. very near relation to a. loaded boiler trolley ; and the ever­observant road surveyor of the district in which this wagon worked, would quite probably consider that 7 or 8 tons, carried on a. sin~le 3-ft. wheel, was more than suffi­cient to bring it wtthin the "excessive weight " and '' extraordinary traffic " clauses of the 1878 Act ; a.nd his certificate to that effect could cause a. great amount of trouble.

For such large loads as this, I consider that the work would be much better done by means of a small light road steamer, having flexible driving tyres which would be unslipping on either paved inclines or any other sur­faces ; and which would draw a. suitable truck or trucks. For greasy paved inclines, smooth circular iron driving tyres will never be satisfactory, whatever practicable degree of loadin~ may be given to them. And hence the necessity for usmg suitable flexible tyres if the engine or carriage is to be kept in control, and prevented from slipping about sideways or even backwards on such sur­faces ; often in much worse condition than those experi­mented upon at Liverpool. By means of spare trucks very little time would be losb by the engine in either loading or unloading-which would be very different with the expensive 12-ton wagon-and the steamer could quickly move the wagons into the loading bays, or in­stantly draw them out. Also, euch an engine would never be bogged on soft ground, or be unable to proceed over a. patch of newly la.id road metal. It could ta.ke its load over a.ny unmade ground, could visit a farm if re­quired, and could transport far more goods in a day than could be managed by the low-wheeled ponderous, self­contained vehicle, whatever its practicable amount of load might be. Besides which, the small flexible-tyred steamer would not be limited to a maximum load, a.s the self­contained carriage is; and so on suitable roads it could take a. paying load of even 18 tons or more, and so far out­distance the work of the motor wagon. There is not any mechanical difficulty at all in this proposed manner of working, the only trouble being the ever-obstructive "law," perpetually holding up its legal finger, and threatening, You must not do this, a.nd You mu~t not do thab, and 10l. fine or imprisonment if you do!

Originally, speed was unhmited, and rates of 30 miles an hour were often attained in the days of Gurney, be­tween 1825 and 1830. Then in 1861 speed was limited to 10 miles in the country and 5 miles m the town, which was reduced to 4 miles and 2 miles, respectively, in 1865. The~Je remained the legal rates until18~6, when liberty to

'

tons at 14 miles was given, to be immediately re­dun 3d by the Local Government Board to half that u~e ht at only 12 miles an hour. And what w.e now yet

we•g. ·s not merely permission to use a little extra requu~ 1

1 ·n a motor wagon- useful as tha.b would be,

mo.teru~ 1 '"' • 1 · th th b b liberty to proceed in a. .commerm~ manner Wl e u tor wagon, the self-conta.med ommbus, and the sma~l

mod steamer together, in such a. reasonable mam~er as IS roa d din every other country of the world, w1th the a~oole :xoeption of our own ma.nufac~uring England.. So :hn~ the smallest motor oycle, the ordma.!Y motor ?arria~, the largest motor wago~, the ~elf-contamed ommbus, t e

d teamer the tractton engme, the road roller, and the ~a shing engine migh~ all have equal chances ~f being P otus to practice in mannera that would be am table to pu . m ·n· capabilities· and thus each of them be !~:~~~~r aftowed to drift' into that. pa.rti?ular sphere of usefulness, for w~ich it should prove Itself m actual work, to be the most sUitable.

And in order tha.b this may be a{)bieved, would I_lOt the following concessions be both necessary and suffi01ent. to enable us to take p~ssession of all tha.b road l~comoti ve

d that still remams to be po~essed, and ~hi~h we are ~~ll able to do if only the exiStmg legal restr10t10ns were removed : T -Al

Fo1· Goods ?'aJJ~o.

Weight of material ... ... up to 6 t<?ns. Width over all . .. .. . ... , 90 m.

Speed Us~d to d~~w o~iy tw~'vehicl~. 6 miles.

For Passenger Traffio. Weight of material ... ... up to 6 t<?ns· Width over all ... ... .. . , 84 m: Speed for oountry omnibus ... " 12 m1les.

Yours sincerely, L EONARD J . Tonn.

97, Queen Victoria-street, L ondon, E .C.

THE COAL-MINING INDUSTRY. To True EDITOR Ol!, ENGINEERING.

Sm -I have taken your publication for 20 years, and consider it about the best publ~ahed, for. the value of i.ts information· hence why I wnte to pomb out .the mis­leading figu;es you give this week re ~be a.bo~e mdustr.y. I am sure you do not publish them With the Idea of mis­leading the public ; but, as a matter of fact, they do.

You say the men have worked an average of 5.67 days per week for the month of M~rch, and that, therefore, the scarcity of coal does not arise from neglect of work on \he part of the colliers.

AB one who sends in one of the returns to the Labour Office every month, let me point. out to you the:t ~.67 refers to the number of days the pits have been wmdmg coaJ and not to the number of days the men have worked. The' Labour Office does not ask for the information, and, therefore cannob have it; and I doubt if the Labour M.P.'s w~uld allow them to ask for it,. as it is ~ell kno:wn to them how badly the men are workmg. It ~s nothmg unusual for collieries to have 25 per cent. of their men off.

I am, &c., April 30, 1900. ONE INTERESTED.

YACHT :MEASUREMENT. To THB EnrroR oF ENGINEERING.

Sm -Judging from the wording employed by Mr. H. c.'Vogt M. Inst. Danish C. E., in a. paper he recently read at our Institution of Naval Architects, on "Yacht Measurement ,, (for racing purposes), ''with some remarks on the action of sails, ,, and judging from the discussion which followed, it would appear that the author of the paper and his audience are equally ignorant of the efforts made by others for several years past in the same direc­tion. Mr. Vogt's principal proposal is to introduce dis. placement into the ratio~ formula in such a manner a.s to pub a premium on displacement. This has been preached incessantly, in season and out of season, in signed and unsignoo articles, in lettel'il to the press over the signature "Thalassa,, in signed and unsigned pam­phlets, in proposals to the Yacht Racing Association, in chapters on the "Rating- Rule , in the Badminton Series on "Sport,"in conversatiOns, and in endless private letters by Colonel Bucknill, ever since 1892, when he first saw Mr. Herreshoff's proposal noticed in the Field of December 17 of that year, viz , that the rating of ra cing yachts should be found by multiplying water length by square root of Rail and dividing by cube root of tonnage. The late Mr. Dixon Kemp, as the then Y a.chting Editor of the Field, suggested, on Decem her 24, 1892, that dis­placement should be used instead of tonnage-as a divisor. Neither Mr. Herreshoff, nor Mr. Dixon Kemp, followed up the subject with any persistency; but appa.· rently let it drop. Colonel Buckmll, on the contrary, has wor~ed a:t it ever since1 and has suggested nUT;nerous modtficat10ns of the origmal proposal, one of wh10h, so far as the divisor is concerned, has practically been adopted in the new French rule, which is to come into force next ye1r-vide pages 178 a.nd 179 of Badminton "y ht' , 1 . a.c mg, vo . 1.

. On September 18, 1896, a careful analysis of the rela.­hon of Bpetd, sait area and cUsplacement, was written by Colonel BuokniU, and published in ENGINEERING. It had been wotked out by Colonel English, Rear.Commo­d?re R.E. Y.C., and a good mathematician. He based hlS calculations on hlS own towing experiments with models, and on the late Professor Willia.m Froude'$ method of sep1rating the resistance due to skin friction and that due to wave and eddy making. A summary of these ca.lcula.tions and the conclusions arrived at by Colo~el English, and of other matters and writings, was puhhebed ijy Colonel Bucknill 4t Soqthampton, in 1~97,

E N G I N E E R I N G . •

and circulated privately to friends, fellow spo~tsmen, and yacht designers. A few abstracts from thts pamphlet may be interesting at the present moment. "The result of the Y.R.A. rule will be small displacement ~or each class, very much over-canva:sed.': C~lonel ~nghs~ ... May 1896. ''Differences m m 1dship sect10n w11l not have' much value under this rule. , Ibid. . "A rule o~ghb not to fetter design in any way beyond sa.ymg that a g1 ven weight of hull ~hall have 9: given propulsive power (dete~­mined by previous expenence) allotted to It . .. . . and If this be done I think that the type of boab which 1s a com­promise, but meets ordinary conditions, would be the re-suit. , . . • Ibid. . d ·

" From my tria.Js the total resiStance of the one es1gn Solent class of boat at ordinary racing speeds varies a.s the fourth power of the speed." . • . !bid_. .

" If the sail areas of two b!'ats of sumlar type ~e made proportionate to the two-thud powe~ of thetr dt~plac~­ment~,, it can be proved ma.thematt~all~ that the1~ speeds vary as the twelfth power of their dlSplacements. Ibid.

'' Hence the rule should be : . . (1). Fix the sail a~ea for the ?oat of largest diSplacement

in a class from prev10us expenence. (2). Allow a boat of smaller displacement to carry two­

thud power of her displacement. (3). Allow a boat of smaller displacement ti!lle in !lccord­

ance with the one-twelfth power of relative diSplace~ ments." .

This proposal amounted '&O a pure d1spla~ement rule, the class limit (1), the sail area {2), at;ld the time scale (~), all depending_ an~ being expressed m terms of the diS­placement. But Ib was too perfect. It assumed the boats to be of the same type, and this would only occur after the rule bad been employed for many years and the best type unde~ the rule de.monstra.ted. Moreover, t~e boa.ts of small di9placement m any class would · be assisted by time-an assistance which they probably would nob re­quire in which event the rule would nob encoura~e a healthy amount of displacement, but would fa.vc;mr light displacement freaks a.s much a-s any rule yet de~•se?.

Ab the time (September, 1896) Colonel Buckmll, m cor-responding with Colonel English, said: .

"It is absolutely necessary to have the time scale and classification on continuous curves. . • . ,

"I do not see how displacement is to be found for boats over 30 ft. or 40 fb. . . . " .

"I do not follow the argument as to length not bemg necessary in the rating of formula .. . . " . .

" I think it would be better to classify by a hne or rating equal" (proportionate) "to the two-third power of displacement and to limit sail on each boat to the square of her rating " .•. which would then, of co~use, be pro­portionate with the two-third power of her dtsplacement. The proposal placed before the last gene.ral meeting of the Y.R.A. differs but slightly, and is an Improvement, the classification and rating being si~ply by length. of. hull on water line which can be chosen m each class hmtt, so as to inconvenience present owners as little as possible, if at all · and the allotment of sail being precisely the same as suggested in 1896, viz., proportionate to the two-third power of the yachb's displac9m ent. .

Colonel English replied, Septe~ber 1~, 1896, sho~mg how length could be. introduced m to hiS l?roposa.ls if so desired, but demurrmg as to the necessity. He also added: .

"It seems to me to be absolutely essential to any logical rule to devise some method of measurin~ displace­ment, .. . "Every merchant vessel is pract1~1ly sold by displacement, i .e., to carry so much dead weight on a given draught, and there ~s no end of a .wrangle if .a. vessel is, say, 20 tons short m 4000.. The displacement 1s accurately calculated to a. ton for every man-of-war, and I do not see why much difficulty should arise for yachts." ... " I agree with you that it would be much better nob to make separate steps for classification ... ". .

Much of this and a great deal more was publiShed m ENGINEERING on September 18, 1896, to ~hich ~ refer Mr. Vogt if he desires to know the manner m whtoh the problem of the measurement of racing yachts as regards displacement and sail area., has been most carefully worked out and examined by Colonel English (late Royal Engi­neers), who also ~ea.d a paper early in 1~9.6 at the Institu­tion of Mechamca.l Engmeers, explammg the mathe­matics of his towing experiments.

Although the resulting rules proposed by Colonel English do nob appear likely to. meet th~ reguireme~ts of racing men, many facts received eluCidatiOn durmg his examination which are most valuable.

The same can scarcely be said in connection with Mr. V ogt's manner of atta.ckin~ the problem.

The only valuable J?Ort10n of his proposed rule- the divisor-was made origmally by'Herreshoff in 1892, and has bsen recommended over and over again by others since that time. The proposal to rate yachts by their sail area. -the numerator of Vogt's fotmula- was made by Ricbard­son during the discussion before the Council of the Y.R.A. prior to the adoption of the l~ngth an~ sail area rule in 1886, and was carefully exammed, and Its defects fully recognised and enumerated in the arguments of other de­signers. It is true that these defects would be greatly modified by a displacement divisor; but the omission of length of hull-one of the most important speed-produc­ing elements in a. yacht-is an objection which holds good now g.uite as forcibly as in 1886. Moreover, a premium on dtsplacement encourages greater length of hull, as any added weight is better disposed for speed in that manner than in any other. Hence, in all displacement rules extreme length of hull should be even more carefully guarded a~ainst than heretofore. It is, therefore, certain tha.b Mr. Herreshoff's rule of 1892, viz. , linear rating to

Hull, length, Jea.il . vary as 11 • - IS greatly to be preferred to

';J Dtsplacemenb

• 593

Mr. Vogt's modification of it in 1890, viz, linear rating

t oa Sail2 and the contention of its author o vary ...., . ' Di.iplacement , ..

that (sail)2 is a measure of the yachts . stabihty, because it happens te be of the same a1gebra.to form as. that of the moment of stability is, to say the least of lb, vera far fetched ; and in verity it can yery safely ~e a.sserte that the sail area itself (and nob ItA square) 18 the true measure of a yacht's stability, for . ~he reason that a.ll yachts are canvased up to their &t~bihty, .so far as thell' requirements necessitate-the crmser bemg, of course, less severely canva.sed than the racer.

That yachts in the small classes should be actually weighed to find their displacement was first .propose~ by Colonel Bucknill in 1896, and he. has urged 1t ever smce, and Mr. Vogt's l?roposals to wetgh large y~cbts do nob appeal to the engmeer, !LS he appears to ent~re~y neglect the friction of the cup pistons m the hydraulic Jacks em­ployed for the purpose. . A small. floating dock would probably succeed if spe~Ially .destgn~d to record the weight carried at any .gt!en Immersion~ as also the quantity of water held IDStde the dock ~Imultaneously. Such a. dock could probably be usefully e~ployed ab any yachting centre, and thereby pay a good mterest on the money so in ves~ed. . . . ,

Colonel Enghsh eVIdently constders that the des1gner s knowled~e of his yacht's displacement should be em­ployed- If one may judge by the sentence already q~oted; and there cannot be any doubt that all modern destgners know their ya{)hts' displacements within a very small margin of error. Even. if the bo~t does not float ~xactly on the designed water line, her displacement per mch !Jf immersion at water line is known, and the calculated dis­placement can be corrected accordi11gly. The questio!J, therefore, with regard to large yachts s~ems, to be:. Will the Council of the R. Y .A . accept a designers certificate of displacement in the same way th~t the sailrna.~er's cer­tificate is already accepted? Or, will the CounCil prefer the expense of some special dock or weighbridge for large yachts? If neither of these be acceptable, it would appear that the wei~hing of boats to obtain their dis­placement, and a ~atmg rule in which ~ispla.c~menb is a factor or with whtch an allotment of sa1l area IS ordered, can o~ly be entertained by small yaohts.

If the Council were satisfied with a proportional dis~ placement for the purpose of racing measurement, it might be obtained by the product of. hull length ~nd be~m on water line, and the depth of Immersed nnd-sect10n measured internally at quarter beam. The latter measure­ment would, however, be most difficult to obtain with the required accuracy in the miniature fleet, for which the actual weighing machine is immensely to be preferred.

We hope to see displacement introduced into the ~a.ting of racing yachts by one or other of the proposals avatla.ble, any one of which would be a great advance on the type of measurement hitherto employed by our yacht-racing men in this, and, indeed, in any other country ; but it must not be forgotten that France has adopted a. rule of the k ind which is to come in force with the new century; and we should not lag behind her.

April 29, 1900. THALASSA.

THE FLIP OR JUMP OF A GUN OR RIFLE. To THE EDITOR OF ENGINEERING.

SIR,-In your last issue, Mr. John Rigby gives some interes ting particulars on the above subject, to which, with your permission, Sir, I will add a few remarks.

The springing of the hand of the stock has an important influence on the flip or jump of a gun or rifle. Light game guns, firing full charges, have been known to shoot 12 in. low ab 40 yards range, this being caused entirely by the springing of the stock. It has been proved by ex­periment that a gun or rifle may be made to shoot high or low simply by strengthening or weA.kenin~ the hand of the stock. Mr. J. Bridges-Lee in his article makes the following incorrect statement :

"Double-barrelled guns and rifles jump so much away from the line of sight that the barrels are set ab a con­siderable angle to each other with the object of compen­sating for lateral jump."

The principal reason for putting double barrels together at an angle, lS to compensate for the shortening and con­sequent springin~ of the barrel being fired. The action is as follows: The mternal pressure in the barrel being fired causes circumferential expansion, which induces a decrease in the length, the result being that the pair of barrels are sprung round towards the one being fired.

This matter was fully exolained, and a series of experi~ ments on the subject described, in your valuable journal about 15 years ago.

I will conclude with the remark that problems in gun~ nery require very careful handling even by experts.

Yours faithfully,

Roedean, Brighton, May 1, 1900. HORATIO PHILLIPS.

FRENCH STEEL MAIUNG.- The production of rolled steel in France last year was 1,253, 701 tons, as compared with 1,174,075 tons in 1898. In the.~e totals steel rails figured for 265,796 tons, and 242,806 tons respectively •

THE ELE<YrRIO LIGHT AT SuNDERLAND.-Mr. J . F. C. Snel1, electrical engineer to the Sunderland Town Coun­cil, has reported tv the lighting committee than the profits on the corporate electric ljght undertaking during the past year amounted to over 1000l. Of this sum 700l. has gone towards the reduction of the rates, and there remains in hand a. balance of 350l. The committee will decide shortly whether this balance is to be devoted to the reduction of the cost of the illuminant, or to building up a reserve fund.

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E N G I N E E R I N G. 595

SIX-YARD DIPPER DREDGE. CONSTRUCTED BY THE BUCYRUS COlVIPANY, SOUTH MIL,¥AUKI~~J~, WISCONSIN, U.S.A.

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FIG. 3.

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THIS dredge, which is illustrated on page 5 6 and on the present page, is one of a series, built by the Bucyrus Company, and possessing many points of interest. The great reduction in cost of dredging during the past few years, and the low price at which contracts are now taken, have bePn largely brought about in the United States by the use of these large and powerful dredging machines. Some years ago a 3-yard dipper dredge, with 12-in. by 16-in. hoisting engine was considered advanced practice ; but now they are built with 18-in. by 24:-in. engines and a 10-yard dipper; e,·en t his size is likely to be increased. This development has resulted in t he cost of dredging being reduced to one-half of what i t was eight or ten years ago.

The dredge illustrated, and which was built by the Bucyrus Company, of South Milwaukee, is an excel­lent example of a modern dipper dredge of fair power and capacity. The hoisting gear is on the direct wire­rope system ; the chain system of hoisting answers very well for smaller dredges, but for high power and speed, the hoisting chain becomes too large and c~mbersome. Hoisting chains are also liable to break Without warning, and when such a chain fails and leaves everything in the bottom of the river, consider­able delay, trouble, and expense are involved. Many experiments have been tried with wire-rope substituted for chain in the usual way, but t he great wear on ~he rope, d.ue to its speed of travel and frequent bend­mg, causes 1t to wear out rapidly, and the expense for renewal is quite equal to that of the chain. The Bucyrus Company has therefore adopted the principle (first us~d and buil~ by them for l\1r. John Kennedy, M. E., Chtef_ Engineer, ~arbour Commissioners of Montreal) of a smgle-part wtre rope running at slow speed over very large sheaves, and to operate which the engines were. ~eared up the necessary amount to give the requt~lte pull. In the dredge illustrated the hoisting r~pe Is made of extra flexible plough steel, 2! in. in dtameter, and ~he engines are 16 in. by 18 in., with drum ~n~ gearing a,s illustrated in Fig. 2, page 586. The hotstmg gears, as will be seen, a re double for the aak.e of strength. They are each 9ft. in diameter by 1~ m. fa~, a~d drive a grooved d rum between them of dtfferenttal dt&meter, the smaller producing a heavy ~ull at slow speed. when. th~ dipper is on the bottom, f nd the rope rap1dly chmbmg to the larger diameter or the purpose of hoisting the dipper at speed. The

FIG. 4.

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effect of this is that the actual worldng speed of the dredge is very consider& ble, and this speed is fur ther aided by the grea t fre edom with which the dipper drops to the bottom and o\rerhauls the wire rope. It will readily be seen that in t he three-purchase chain dredge t he dropping of the dipper must necessarily be slow, as it has to overhaul the long and heavy hoisting chain. In this case the weight of the rope is practically a negligeable quantity, and the dipper drops with absolute freedom and great speed, being con­trolled by a brcJ.ke at the proper moment. To permit t he dipper to drop freely through t he water without too great impact, its door is made double with a part of its aree:t opening inwards, so that it can pass through the water in its descent with slight resistance.

The hoisting drum is driven by two powerful band fr iction clutches of a special type, designed and patented by Mr. A. W. Robin son. This type of clutch is one which has proved itself peculiarly adapted to the work, and its o~eration has been very suc­cessful. Although carrymg such a very heavy load, t he power can be applied either gradually or instantly at the will of the operator. It is frequently necessary or desirable to slip the friction clutches in order to ease the engines in case they become stalled. The two clutches are both actuated by one steam cylinder attached to t he main frame, directly in line with the shaft. The movement of this cylinder is controlled by a very small slide valve and compensating links, so that the mot ion of the piston follows the motion of a man's hand in operating the lever. There is thus no necessity for any dash pot or oil cylinder, or other restraining mechanism. The two main pistons are keyed fast to the intermediate shaft , but only one of the hoisting gears is keyed to this shaft; the object of t his is to allow the gears to accommodate themselves so that each will do half the load.

Another speciality in the design is that no space is occupied upon the shaft by sliding collars or other devices requiring end motion. The hubs of the main hoisting gears are close to the bearings, and the main hoisting drum fits freely between them, and is lined with phosphor-bronze, so as to enable it to run loose upon the shaft.

The illustration, :Fig. 1, on page 586, gives a good idea of this dredge. I t will be seen that all its parts are well balanced and in good proportion. The boom is of steel 50ft. long, and the wire-rope sheaves are of

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cast steel 8 ft. in diameter. The A -frame is also of steel and is stepped upon the upper deck on top of t he spud casings in such a way that when the dredge is pinned up, the t hrust of the A -fram e is practically carried upon the spuds, and the stresses resulting from it are not transmitted through the hull. The spuds ~re of Oregon fir, 36 in. square in one stick 50 ft. long. They are likewise operated by wire rope for movement in both direc­tions. There are two ropes to each spud, and both ropes are attached to a drum, which is fitted with a powerful friction clutch and brake, and is operated from the main engines. In this way the entire power of the main engines is available for handling the spuds and for pinning up the dredge. Although the spuds are so la rge and heavy, t hey c!l.n both be raised simul­taneously with considerable speed, all the operations of throwing the clutches and brakes being performed by steam ; no racks and pinions attached to the spuds. The arrangement is shown in Fig. 1, on page 586, and Figs. 3 and 4 a hove.

The swinging of the boom is effected by independent engines, and by wire rope. The engines are geared up in such a way as to give ample power and speed, and the dredge when at work can readily make two dipper loads per minute from a depth of 25 ft. Steam is furnished by one cylindrical boiler of the Scotch marine type, having two corrugated furnaces. The boiler is 10 ft . in diameter by 9 ft. 6 in. long. The hull is 38 ft. wide by 110 ft. long by 12ft. deep, and is stiffened by two internal steel trusses.

Altogether, this dredge is an excellent example of its kind , and all t he details have been very carefully and satisfactorily worked out. It has been at work during the season of last year near Detroit, and we understand it has given satisfaction from t he start, there having been no breakdown or mishap of any kind. The dredge was built from designs of M.r. A. W. Robinson, M. Amer. Soc. C. E., the engineer of the Bucyrus Company.

HAVRE TRAMWAYs.-The number of pagsengers carried upon the Havre tramways in 1898 was 11,763 992 as com­pared wit~ 11,131,363 in 1897; 9,659, 754 i~ u396; and 8,670,227 m 1895. The revenue acquired in 1898 we.s 66,468l., as compa~ed with 65,3~7l. in 1897; 46,115l. in 18~6 ; an~ 42,214t. m 1895. The lines are worked by eleo• tnc tract10n.

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INDUSTRIAL NOTES. ~HE fortieth annual report of the Carpenters' and

J omers' Amalgamated Society, just issued, extends to a volume of 436 pages, full of minute details relat­i':lg t<? the union. In reviewing the year 1899, atten­t ton 1s called to the fact that the expenditure ex­?eeded that of the previous year by 16,473l. , of which m~r~ased amount ll,606l. was expended on trade prtvtleges alone. It was not a year of great st rikes, but it was what the report calls "a turbulent one " from beginning to end. There were numerous dis­putes, mostly in places where wages were low, and the c~nd~tions of w~rkin.g were not up to the level of other d1str10ts, resultmg 10 struggles as to working rules, the least satisfactory of which, the report states, were attempted to be thrust upon the members by the cen.tral federation or associations of the employers, and whtch the members of the society resisted, with the sanction of the council of the union. Of course, there is another side to this- the employers accuse the men of trying to enforce rules injurious to the trade. These naturally opposite views eventuated in disputes and stoppages of work. The total cost of those troubles was 20,307l., the largest amount that the society ever expended in one year on labour disputes.

As a set-off to this increased expenditure the report says that large numbers of new recruits joined the society, no fewer than 10,682 joining in the course of the year. At the commencement of 1899 there were 774 branches, with an aggregate of 56,634 members; at its close there were 61,781 members, a net gain in the year of 5147 members after allowing for deaths and exclusions through arrears. This in· crease beats the record of any previous year, and is regarded as most satisfactory.

The total income of the society in 1899 was 150,653l. 2s. 6d. Of that total 140,294l. 7s. 9d. was from contributions, levies, &c.; 4827l. 13s. 5d. en­t rance fees, &c.; 3625l. 2s. 2d. interest on cash and from investments, sale of reports, &c.; the balance being miscellaneous receipts.

The total expenditure amounted to 122,835l. Os. lOd. The chief i terns in this large sum were expended on provident benefits, apart from the amount spent in disputes, before referred to. The cost of unemployed benefit, inclusive of fares, sending men to situations, &c., was 15,341l. This is a large amount consider­ing the state of trade; it was rather larger than in the previous year. Sick benefit cost the society 33,413l. 7s. 1.; accident benefit, 3495l.; medical certifi· catef:l, 979l.l8s. 8d.; and sick stewards, 1232l. 16s. lOd ., all of which amounts had to do with the health of the members, as in a. friendly society. The next large items were for superannuation benefit, the total cost of which was 16,267l. 19s. 6d. in the year, and funeral benefit, 5806l. 14s. 6d. Tool benefit was large, many disastrous fires having taken place; the amount so paid was 2905l. 19s. 8d. The benevolent grants to members in distress and t o other trades, amounted to 4462l. 7s. 6d.. All these amounts came under the head of provident benefits, in addition to the total sum of 20,307Z. expended in support of trade privi­leges.

The cost of management is necessarily large in a union with 774 branches and an aggregate of 61,781 members. Secretaries' salaries for all branches and general office amounted to 3570l. 2s. 3d.; treasurers' salaries to 1516l. 7s. lOd.; other branch officers and committees, 2157l. 17s. ld.; auditing accounts, 735l. 4s. ld.; rent, fuel, gas, taxes, cleaning, and re­pairs cost 234ll. 12s. lOd.; banking expenses for the year, 332l. 17s. ; printing and stationery coat 3154l. la. 4d., but a port ion of this came back for reports, cards, &c.; postages, parcels, money orders, and telegramCJ cost 1058l. 14s. 6d.; and insurance, 2l. 17s. 6d. The law expenses amounted to 1415l. 9s.; and defalcations to 703l. 4s. Delegations and meetings of the executive council cost 70It. 6s. 5d.; and sum­moned meetings, 388l. lls. 7d. The meetings of t he American Council cost 40l. 19s. 6d.; the Australian, W . 3s. 6d. ; and a general council of the latter, 23l. 10s. 6d. The Trades Congre~s and grants to the Parliamentary Committee and the Federation of Trades cost 168l. 3s. lOd. Various kinds of property purchased for t he use of the branches, &c., amounted to 234l. la. 4d. The remainder consist of several small items, details of which are given.

The cash balance at the close of the year was 200,530l. 13s. 2d., t he total worth, inclusive of pro· perty, houses, and goods amounted to 206, 738l. 9s. 6d., or 3l. 6s. 11d. per member. Of the total balance, 118 93ll. 16s. lOd. was held by 771 branches, the gen~ral office, and the Australian and A~erican di.s­t rict offices while 81,598l. 16s. 4d. was mvested m corporation' bonds or other public securities. The latter amount is regarded as a rese~·ve f?nd for provident benefits, such as superannuatiOn, s1ckness, accidents &c. The cash balances are in the Post Office savings b~nks, or other banks available at short notice in case of need.

The aggregate amount paid a~ benefits to mem~ers, during the forty years of the extstence of the soetety,

E N G I N E E R I N G. is shown by the following '!'able, the cost per member being also given :

Obaraoter of Benefit. Total Amount per Amount. Member.

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£ £ 8. d. •• 674,&64 27 1 7~ • • 47,165 2 4 6 • • 496,319 23 7 ~1 • • 89,201 4 4 • • 47 ,91}6 2 6 2t • • 129,983 6 2 6~ • • 193,490 9 2 8! • • 30,747 1 3 llt • • 25,601 1 4 1,

Unemployed benefit • • • • Tool benefit . .. . . • • •• Sick benefit .. • • • • • • Funeral benefit •• • • • • Accident benefit • • • • • • Superannuation benefit .. •• Trade privileges-disputes • • Benevolent grants . . • • • • Grants to other trades • • ••

Aggregate • • • • •• • • • • 1,635,325 76 16 8t

This is a worthy record for a trade union. The actual a.mQunt spent on disputes is comparatively small, when it is remembered that the primary object of the society is the maintenance of trade pdvileges. The cost of superannuation benefit was 5s. 3d. per member for the whole ;year; the highest amount so paid in any one year was 5s. 6d.- in 1896. The two benefits which cost most are'' unemployed" and " sick:" the former, in 1879, cost ll. 12s. 9d. per member in the year; the latter, in 1893, as high as l5s. 3d. in the year.

of a permanent board, which is still under consiclern­tion. The outburst of enthusiasm by reason of the S?ttlement shows how the operatives regarded a pos­Sible rupture. It was not merely that the concession was made by the employers, but the fact that a ceesa.· tion of work was averted. When the announcement was made at a great meeting at Ashton, cheer after cheer was given, the name of the Mayor of Oldham being bailed with enthusiasm .

The engineering trades throughout Lancashire con· tinue to be well employed, there is indeed, very little change in the position in this respect. Exceptional activity is maintained generally on work in hand, a.ud the reports of trade unions show full employment for all sections of workmen. This applies to all the chief branches. In the iron trades the market has been somewhat unsettled, the effect of which has been to check business of any weight being put through. The possibility of American iron becoming a. serious competitor is one of the causes of hesitancy, but it is thought that the reports are exaggerated to depress English brands. Still it is reported that a number of sales of American pig iron have been effected, and it is said that larger quantities are offering for delivery ere the close of the year. But local makers' prices are still firm, though some sales have taken place below the full figures. In t he finished iron trade prices are strongly maintained, in spite of the fact that only a small weight of business has of late been put through. The steel trade has also been uneettled, .American competition being the cause. Nevertheless, on the whole, the posit ion is not unfavourable, nor are the prospects, so far as can be seen, discouraging.

The Ame?·ican Federationist for April, just to hand, gives us a glimpse of the American trade and labour unions, and how t hey proceed with their organisa­tions. It is handsomely got up, with an emblematical design on the front cover which surpasses anything of the kind in British trade union reports. The motto is -"A bond of silk stronger than brass or &teel." It gives a reproduction of the photographed group of In the Wolverhampton district, new businees, it is de~egatea at the last Trades Congress at Plymouth, reported, continues to flow in, and merchants offer with views of the Guildhall, exterior and interior, freely for various classes of rolled iron for delivery where the sittings were held. It contains an article during the current quarter. But the manufacturers descriptive of the recent formation of a Federation of are very chary of accepting orders except at full rates; Trade Unions in this country, some "British Labour having plenty of orders in hand, they can afford to Notes," various reports and articles. One of the wait . Bars, hoops, and strip iron are in good demand, editorial articles is headed, "Wage-earners, beware !" and there are large inquiries for boiler-plates, angles, The warning is directed against persons not in the girder and other sectional iron for bridge-making pur­ranks of labour-that is, of the wage-earning class, poses. Black sheet makers report a steady demand who, since the popular development of trade unions, for working up sheets and galvanisers' doubles; but have endeavoured to foist themselves upon the labour there is room for improvement in the latter branch. organisations, and the article says' 'the purpose sought Prices generally are firm, with no change from quarter· by them is not calculated to promote the welfare day. Steelmakers appear to haYe been adversely of the cause for which the organised labour movement affectes by .American producers, as some steels have stands. " The same thing has been manifest in England receded to the extent of 2s. 6d. per ton. Pig iron is of recent years, with results not always favourable to in great demand ; some works find a difficulty in labour. The writer then calls attention to the fact obtaining sufficient for their requirements. All classes that "all trade and labour unions under the banner of finished iron maintain full rates, wi th a firm tone as of the .American Federation of Labour are corn· to future deliveries. The general branches of iron and posed exclusively of wage workers, men who work for steel-using industries continue fairly busy, with here wages, and the exclusion of others does not necessarily and there some complaints as to quietude. Engineers, rPflect upon them." Such outside men are reminded ironfounders, boilermakers, tankmakers, bridge and that if they sincerely sympathise with labour, they girder constructors, smiths, and hammermen are well can show it by assistance outside the organisation employed, very few indeed being out of work in corn­better than they can by seeking to become members. pa.rison with·the whole, and some that are out of work In an address to the trade and labour unions, signed may be so from causes other than slackness. Dearness by the President and Secretary of the American of fuel and of raw material have naturally affected some Federation of Labour, they are urged to extend their branches, but not to the serious extent of throwing organisations, as the best means of advancing the the workers out of employment. There are no serious interests of the workers. On May Day, Independence labour disputes on hand, or pending, so far as we can Day, and Labour Day, they are advised to hold meet- see. The disposition is on all sides for peace; and ings and public demonstrations, especially to support hence the relations between capital and l&bour are shorter hours, with the object of ultimately gaining more friendly than they were when trade was less the eight-hours day in all trades in America. flourishing than it now is. It is the output that is

required. On all hands, the complaint is that the supply falls short of the demand, and therefore a stoppage of work is regarded with more dread than it waa when there was no pressure for supplies.

The settlement of the dispute with the card-room hands, ere the close of last week, .was received with great enthusiasm in the Lancashire districts. The dispute was with a s_ection only, called the "datal," or make-day-wage handP, who demanded 10 per cent. advance, or 5 per cent. beyond the general concession previously made. The conference was brought about mainly by the good offices of the Mayor of Oldham, Mr. John Hood, but there was not any strong dis­position on the part of employers to risk a cessation of work, in which not only those directly affected by the dispute, but thon~ands of others would be indirectly affected by the stoppage of the mills. At the con­ference it was pointed out by the employers' repre­sentatives that the great objection on their part to the proposed advance was the .invidious _positi?n in which it would place a few men m comparison w1th the large majority. As the extra 5 per cent. was intended to do away with a long-standing grievance, practically dating from the Brooklands agreement, the employers considered that the matter should have been the sub­ject of separate negotiation, and not form part of the general adYance. Moreover, it might become a. pre­cedent, and the same hands might make some similar demand in the future. In the end terms of settle­ment were agreed upon to avoid friction in the future. The two parties agreed to strike out a. sentence in Clause 4 of the Brooklands agreement bearing upon this question. The whole of the operatives are now, by the deletion of that sentence, under one arrange­ment with regard to advances or reductions i~ wages. It will also help to pave the way for the estabhahment

In the Birmingham district a steady tone has been manifest in the iron market, though the new business coming forward is not so plentiful as it was some weeks ago, and in some instances prices are somewhat weaker. But as makers generally have enough orders on their books to carry them over most of the quarter, the fluctuations in prices do not affect them very much. For marked iron there seems to be no diminution in the demand at full rates, and there is a. heavy output in t.his branch of the iron trade. In unmarked iron there has been some underselling, and the subject was brought up at the meeting of the Unmarked Bar Association. But it appears that the firms in ques· tion were not mem hers of the .Association, and there· fore no aotion could be taken. One was said to ba only recently embarked in the trade, another was stated not to be a regular maker. The members were all loyal to the association, full prices being adhered to in all cases. 'fhere is a good demand for all classes of iron, and no prospects of lower prices at present. It appears that the rules for a Federation of Bar Makers' .Associations have been approved, and will be submitted to a meeting to be held in :Manchester at an early date, when the federation will be launched. The federation will include the Scottish, Lancashire, Yorkshire, Shropshire, and the Midland Associations. There has been a good demand for gas and water tubes, the latter being wanted in large quantities for South

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MA\' 4· I 90~.] E N G I N E E R I N G. 597 Africa.. The bedstead trade is quiet. The demand for galvanised sheets is good, the black sheet bra~ch · 1'e'" The steel trade is and has been very bnsk. IS qu v. b '1 k ... h The engineers, ironfounders, 01 erma era, smiv s,

hour was founded on inaccurate information. No com~unication has taken place between the masters and the men since the strike commenced.

(page 598). This curve shows clearly that UJ? to :o mil~ there is a field for a system of ~on veyance 10 .t e !'fOr · ing of which terminals are not 10curred, and It will be at once appreciated by engineers. b

ROAD LOCOMOTION.* By Profese:or H. S. H ELE-SHAW, LL.D., F.R S.,

l\1ember, of LiverpooL

Apart from these considerations, there .can .be no d:ou b that with the rapid means for commumcatwn of Ided by telegraph and telephone, and of passengers. afdl gof s by means of the railway, the general want lS et o a

~ continue fairly bu~y, very few men out of work. T~~ major portion of the other i~on ~nd ste~l-using industries, and of other metal-us10g 1ndustr1es, . are fairly well employed ; but in some there a.r~ complamts of slackness. Generally, however, there 1s not much to complain of in respect of employment.

The strike of some 300 labourers at Woolwich dockyard last week throws a aide-light upon the

estion of a.n eight-hours' day as regarded frorr;t the ~~rkmen's point of view. 'rhe me~ had been domg. a

od deal of overtime recently ow10g to the war 10 ~0 uth Africa but the pressure being over the men ~re told to 'revert to the eight. hours. There was a

w od deal of discontent as to th1s, and the men pro­~~eded to hold a meeting, but were tol? that no meet­ing could be permitted on the premises ; they ~ust

THERE are s trong reasons for thinking that the subject of mechanical propulsion upon common roads has now reached a point when it deserves the v~ry carefu.l c~:m­sideration of mechanical engineers. .Th~ 1dea of .brmg~ng the matter generally before the Institutwn .for ~tspusston is due to our President, whose far-_reachmg Jud~ment will be a<lmitted .by alJ, although posstb~y not the w1sdom of his choice of an exponent for the subJe?t.

The title. of this paper must be ad~Itted to be ver.y comprehensive, but It seems that wh!l't ~s needed ab th~s time is a discussion of the general prmc1ples of the et?gt­neering features of the question, rather than a detailed description of any particular system.

more speedy means of transport by road. The ~re ab improvements which are needed in our road traffic ave been set forth by Major R. E. B. Crompton, R.E., ~b present in South Africa, and one of our old .members, ~n a paper read by him before the A utomob1l~ Club, m which he clearly shows the vast and benefi01~l changes that the general. introduction .o~ the motor v~hwle v.:o~Ild effect in the rehef and expeditiOn of traffic m our Cities, and especially in the Metropolis.

Nor must the hygienic consider~tions be overlooked.

'ther return to work or leave ths yard. Some Sixty ~~ more resolved to remain, but about 300 wen~ out-' de to hold a. meeting, where delegates were appomted ~wait upon the officer in c~mma.nd, with terms and conditions. He refused to discuss terms ; tl~ose who liked could go to work, others could have tbetr money at 2 p.m. At that hour the gat~s were cl~sed, a.n.d the men were admitted six at a. t1me and pa1d. The1r places were soon filled up, an~ they we~t away sadder, 'f not wiser men. They th10k an etght-hours day ~xcellent, with pleJ?tY of overtime at higher rates­but that is not an e1ght-hours day.

The May·D.ly Labour Festival at the Crystal Palace on Tuesday was intended to be the greatest Interna­tional Labour Demonstration ever k_nown ... There were great preparations for amusements, 1n add1t10n to t.hose arranged by the Palace Company. The ~ommlt.tee arranged for ~even platforms, two ~esolut10ns be10g a11reed upon sending fraternal greetmgs to labour all o~er the wo;ld, and demanding an eight· ~ours d~y, de­cent housing accommodation, old age pensiOns, umversal adult suffrage, with second ballot, and pay me~ t of members and all official election expenses. It w1ll be observed that the nationalisation of all ~be means of production, distribution, and exchange d1d not find a place in the programme.

--The Factory Acts Amendment Bill seems likely to

be a. most contentious measure, judging by tf:le criticisms on the Bill and by the proposals for 1.ts amendment. At a conference held last week, the B1ll was denounced as a retrograde step. The Master Bakers want the withdrawal of Section 23 as to underground bakehouses. . Laundry proprie~ors con­demn the sections relatmg to the laundnes. The PQrliamentary Committee of the Trades. Congress as.k for extensive changes. All these w11l render 1t difficult for the Government to carry the Bill. Some of the unions of large and important industries require more drastic provisions; so that between those w~o regard it as too drastic, and others as not drastic enough, the Bill is in danger.

What threatened to become a strike in the building trades has been averted. The carpenters and .joiners gave notice six months ago that they required an advance of Id. per hour. The employers offered id. per hour, and at a conference held last week the offer was accepted, and a new clause in the conciliation agreement was suggested, which may avert .. ot?er disputes. It seems probable now t h!l.t the conmha.twn scheme will be approved.

---The master builders of Bolton have offered to

advance the wages of the joiners a id. per hour if the men will forego the demand for a reduction of working hours. This offer is relegated to the workmen for consideration and decision.

The ballot taken respecting the millmen's wages in the Welsh tinplate trade has resulted almost unani­mously in favour of the men's demand for an increase of 6 per cent.

The strike of compJsitors at Amaterda.m caused a. stoppage of some newspapers, and pu.rtially BO of others. It is stated that a lock-out was decided upon, but a fresh conference is called.

For many years the uses and importance o~ the tracti?n engine have become more and more recog01sed, and ~ts possibilities in connection with the present war have qu~te recently been brought very strongly before the P!Jbhc. This engine the work of which covers only a portwn of the field fo'r mechanical propulsion on roads, has been very fully d'ealt with before this Inst.itution . a.nd else­where; and it will be, in the first p~ace, mstructive to con­sider what has led to a general revival of a movement for lighter road locomotives, which, about seventy ye~rs ago, in the days of Hancock a.nd Gurney, reached a. pomt that for a time appeared to. be leading .to permane~b results of the most important kmd, but wb10b ended m complete failure. In one sense this revival is undoubtedly due to the passing of the Locomotives on Highways Act in 1896, previous to which, for more than twenty years, a l~w bad existed which might be known as the "Man With the Red Flag " Act, which made it impo~sible for any s~lf­propelled vehicle to proceed at a rate of mo:e than 4. mtles an hour. The immediate cause of the pas9mg of tbts Act was the attention aroused in this country by the success­ful introduction of the motor vehicle for purpo~es of pleasure in France, where the red flag was not a;t any rate used specially for obstruction on highways. Th1s freedom from legal restriction enabl~d ~n enterpri~ing paper, "Le Petit Journal," to orgamse, m 1894, a tna~ of motor vehicles between Paris and Bordeaux, over a distance of more than 700 miles. These trials :proved conclusively the great pos~ibilities of motor vehicles, and attracte~ much attention in this country, ~here, aft~r .the first exb~­bitio.n and trial i? Engla.nd, which was ortgmated by S~r Da.VId Salamons 10 1895 In the grounds of the L ocal Agri­cultural Society at Tunbridge Wells, successful measures were taken to obtain a more enlig-htened legislative treat­ment. We must, however, look deeper for the real causes of the present movement, which can be traced. to the ,gradual feeling amongst all classes of the commumty that mcdes of transport, both for purposes of p~easure and business on the road~ had not kept pace, or, mdeed, had made little progress at all, compared with the great changes which had ~een .effected in sp.eedbcom~ort, and convenience in the dtrect10n of locomot10n y rall.

:Mr. Samuel W. J ohnson, speaking of the ~rogr~ of railways in his Presidential Address+ before thiS Institu­tion showed that in thirty years the annual train-mileage had' increased from 200 million to 350 millions, and re­marked that "Our iron roads are the arteries and veins of the nation." Pursuing this very true and striking analogy farther, it may be said that the capillaries and smaller blood-vessels are in the4' way jnst.as importa..nt A.S the larger veins. Now, whtle the railway arterial systems have developed enormously and satisfactori,Iy, there is still much room in present modes of. collectmg and distributing goods, for Improvements wh10h would materialJy benefit the trade and commerce of the country.

This subject has been ably dealt wtth. by Mr. Shrapnell Smith, Honorary Secretary of the LIVerpool Sel~-P~o­pelled Traffic Association (to w~oru the au~hor IS 10· debted for valuable assistaD:ce m ~any pom~s d~lb with in this paper, and particularly m connectiOn with the final section). In his paper, ~ead: before t~e Congrees of the Sanitary Insti tute at B1rmmgham m 18.98, he points out that with motor vehicles, not only will our streets be less off en si ve, especially in summer weat~er, but exposed food-stuffs willle~s frequently affo:d a n-zdu& for organisms conveyed by dtC3semmated partiCles from the roads · and further, that the disintegrating effect of the horses~ hoofs which accounts for most of the dust of summer and the' pasty slime of winter, will be to a. great extent obviated. The sanita,ry advantages of the motor vehicle have also been recognised and e.trongly urg~d. by many medical officers of health and surveyors to mum01pa.l and urban councils. This shows, then, what forces are at work urging us, both for light and heavy. traffic, in .the direction of utilising more efficientlJ: and With mec~am~l power the 100,000 miles of road which we possess m thl8 country.

From this side of the question we natura;lly turn to con­sider the difficulties of the problem, and It must at once be admitted that these difficulties are very great. The author has frequently s~en the S!Jbject referred to as a. question of mere mechamcal detatl, and the progress of the railway locomotive mentioned as a proof that these mechanical difficulties will be easily and rapidly overcome. Moreover, the whole. blame for small progress ;m~de, &nd for previous failure, lS often thrown upon restnctive Acts of Parliament. The truth is that the argument of the railway locomotive, so far from giving any grounds for .the hope of an easy solution of the problem of road locomotion, really tends in the opposite di.re.ction. In the first pl:\~, rail ways are one of the mo t strikmg examples of the nature of mechanical progress first pointed out by Reuleau~, that machines became more and more perfect as their restraint by what is called "pairi~g " was m<?re com­pletely effected; i .e., as the mechamcal boundanes com­pelled the parts to move with more certainty under re­quired condit~ons. The provision ?f a.suitabl~ tr~ck, ~pon which the tram moves and by which Its motiOn Is guided, is the real secret of railway development. Hence it is that with a ste~l wheel rollin~ upon a bard smo<?th track, a continuous mcrease of weight and of tractive force, together with increase of speed, is enabled to be obtained. Tlie conditions of the historical "Rocket" were a weight of 6 tons, a speed of from 20 to 30 miles an hour, and a. load of 20 tons ; while the modem locomotive and tender together weigh lOO tons, having a speed of over 60 miles an hour and drawing a load of 300 tons. Now this result has been' obtained by increasing the number of wheels, until the locomotive and i~ tender may have the weight distributed over from 16 to 20 wheels, ea.ch resting upon a hard smooth surface of contact; whereas the motor vehicle, a.t any rate at present, is limited to four wheels, which have to run upon an uneven surface which, if it is hard, intensifies the action of shocks and vibrations, and if it is soft, causes a.n enormous amount of resistance. The load thns being on four wheels, both this sinking and shock are magnified as the load is increased; and therefore inventive effort has been naturally almost entirely directed to lightening the working parts for obtaining a given power, and this cor­respondingly diminishes the tractive adhesion which is a necessary feature for succeesful workin~. In s~ort, the conditions of ~he problem !l're~~ch ~to mvolve .tmproye­ment exactly m the opposite d1rect10n to that m wh10h the rail way locomotive has been successfully developed.

No doubt the progress of invention will ever increas. ingly enable a greater amount of power from a given weight of motor to be obtained; but the surface to be moved over, which is the real difficulty of the road loco­motive, will remain the chief factor of the problem.

The first section of the paper ie, therefore, devoted to the mechanical problem of the behaviour of the wheel upon the road, and the progress which has been made in this direction.

The dispute in the Potteries eventuated in a lock-out of, it is said, about 20,000 operatives on Saturday last, the demand for a. 10 per cent. advance being refused by the manufacturers. The operatives have resolved to stand firm and fight the matter out. It is to be regretted that conciliation was not able to avert a stoppage of so many workers. Conciliation used to be popular there.

Railways are undoubtedly the cheal?est sy~te.m of laJ?d carriage for long distances, but there lS a nnnunum dts­tance below which the disproportio~ bet~een haula~e and terminal charges operates to theu .detriment. Th1s feature of rail way transport, and t~e ser10us con~equ.ences of "breaking bulk," are exhaustively ~ea.lt ~1th m an interesting and important report, pubhsbed m .1898 by the Special Light Railways Committee of the Liverpool Incorporated: Chamber of .Commerc~ ; in w~ich report it is made ev1dent that Ltverpool 10 ~art1cular suffers from these causes, and what is true of Liverpool is pro. bably true of other great commercial cities. Cartag.es and terminals exceed the haulage charges over short dis­tances by rail, while they become only a very small percentage of the whole when the distances are consider­able. It must be obvious that a motor vehicle, which can travel from any one point to the other, which absorbs the short cart ages in.to. one stra.i~htforward _journey, and which absolutely ehmmates rallway termma~ charges, has a wide and promising scope for applicatiOn. Mr. Alfred Holt, one of the leading shipowners of the country, has for many years urged the n;ecessitJ: of ob­viating these terminal charges, concernmg which he states that the matter of handling is a "giant, and the transport a wharf, and the giant is daily growing larger, and the dwarf smaller.''

The relation between these two charges may be shown in a very striking manner by plotting the terminal and conveyance charges, worked out in pence per net ton­mile, tak~n from the Government Blu.e ~ook. of 1.892, dealing With the rates and charges, and IS g1 ven m F1g. 1

The ~econd section deals with Steering and Turning. The subject of Motive Power is treated in the Third

section, which is divided into internal combustion motors or oil engines, external combustion motors (steam), and electrical motors. In this section Transmission and Gear­ing are briefly dealt with.

Finally, a summary is given of the results which have been obtained, and certain general conclusionsl together with an appendix containing some notes and Taoles.

.The strik.e of patternmakers in the Leeds district still continues. The statement, in our issue of the 20~h ult., that it had ended in an advance of ~d. per

-* Paper read before the Institution of Mechanical

Engineer~. t See ENGINEERING, vol. lxv., page 611 .

•

I.-PnoBLEM O.b' THE WHEEL RoLLING UPON A RoAn.

When a wheel with a hard rim rolls upon a level hard surface, every point upon the wheel follows the ourve shown in Fig. 2, a; and since each point on the tyre comes in succession perpendioularly upon the surface beneath, there is no appreciable resistance to the motion. When, however, the surface beneath is either sofb, Fig. 2

•

b, or irregular, Fig. 2, o, the wheel no longer rolls in the Aame way, and the invaluable properties which it pos­sesses are in a greater or less degree destroyed.

Now it is difficult, from any data. at present avaiJable, to separate the amount of resistance respectively due to each of the two foregoing causes. But in F ig. 3 are plotted, from T elford and Babbage's data, the resistance to traction on roads of various kinds; and here it would appear as if a. soft road involved greater resistance than an irregular one, and was more to be considered.

The truth is that, when we are considering the question

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E N G I N E E R I N G. comes serious, but that the vibration which occurs tends a motor vehicle may be subjected when it has to run in­greatly to destroy the structure of the motor vehicle, and disorimina_tely up~n. th~e various kinds of road, unless makes the problem of keeping in working order the mn- some spec1al provts1on 1s taken to counteract such in­chine parte which it will be seen are necessarv for auto- fluences. Fig. 5 gives a good illustration of the severe matic action, incr~singly difficult. . ' . effect produced by~ bad oros..qing. Now, obviously, the

Mr. J . . Brown, of Belfast, h~ l!lvented, an .mstru- ~emedy for shooks ts a means of causing the vehicle and m~nt (wh10h ,h~ has called t~e V1agrafh ) wtth the tts load to ride over the obstacles without being lifted obJect of obtammg aut?g~aph1o recor~s ~ the s~rface of bod~l~; since a reference to Fig. 2, c, shows that roads. The nse of ~h18 mstrument md10ates, m a .re- I a hftmg of wheel and axle must take plac~, unless mark~ble way, the v1bratory effects pr?duced accordmg the. unevenness of the roa<i. is .d~stroyed by being pul­to dtfferent states of roads of nommally the same veriSed or removed ; and thts hftmg, which amounts to

'FifJ · ]. RiLATION 8ETWU:N T~RMINAL AND CONVEYANCr.

6 CHARQ£S ON RAI LWAY8 ( CLA8SIS 3AN04-) Fig. 4. HORS£ POW£R VtLOCITY CURVtS

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Orduuuy Ccbb"Le Swn..e.s --------------­Pre.sh ECArth 10 15 :/.0 :JO ··-·----·---- ---·---------- ---- MILES PER IIOUR

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VIBRATJO~S CUE TO ROAD SURFACES , ntCORDEO BY VIAGRAPH .

I I • - -

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- ----·-S377.D

of the motor vehicle, the opposite is the case, for while the amount of the resi!tance due to the softness of the road remains J?ractically the same as the speed is in­creased, the resl8tance due to obstacles which cause shocks and vibrations rises rapidly. MM. Bovaine et Julien, in their ''Tableaux Nu meriq ue Gra.phiq ue," have investigated the horse-powu up to speeds of 50 kilometres (31 miles) an hour for varying loads. It is nob necessary to reproduce their numerical investigations, but the Sel'ies of curves which the author has t ranslated into English measures, Fig. 4, indicates clearly the great increase of resistance as the speed increases. Now it must be remembered that t is not merely the increase of resietance itself that be-

• - •

• • f. iACAUI\M (FAIRLY GOOD) . ., Fig. 5 . • ' . ....

L~ - ft'!.. - ---~~~--;T"';_ll'J•\o::':w~..,_--,l~~~--hlr;r7'irtilv~~=\1t:;::::::>""~ ~t:fttw~~-..r-~,.....,,J'-

DEEP DEPRESSION SHOWS CROSSING

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MACA.DAM ( BAD .

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SETS ( BAD) .

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character, and the curves which he has given of macadam roads in various parts of the country show remarkable and instructive differences. The city engineer of Liverpool, Mr. J. A . Brodie-who is using one of these instruments-has kindly taken, specially for this paper, a. series of curves which are re­produced in Figs. 5 to 9. From these diagrams it will be seen the difference in the character of vibration on asphalte and wood pavement compared with that on sets or macadam road, and shows to what different influences

* P roceedings, Belfast Natural History and Philoso­phical Society, 1800.

-

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Fig.b . \

Fig. 7. (DeFectint

•rill be t ·epUu:ed)

Fig .9.

a change of direotion of the vehicle and its load, must be accompanied by shocks and consequent loss of power. Sprin~ under the body of the car are the natural method of aoh1eving this result, since even if the wheel rises, the springs give so as to allow the main body of the load to pass onwards over the obstacles without being lifted bodily. But even ~ith springs, t~e periphery. of the wheels have to sustam a. shook wh10h causes n01se and destruction of the wheels themselves, and the best result is obtained by placing a.n elastic medium between the wheels and the road.

More than 50 years ago, a brougham was running in L ondon with pneumatic tyres, which were the inven-

tion of an engineer, Mr. R. W. Thompson. This inven­tion did not attain a practical success at the time, for reasons so well understood by en~ineers, viz., that the mechanical appliances and m~tenals available at that time did not enable the mventor successfully to oope with the prac~ical dif!iculti~s in ~be ~ay of its commercial constructiOn. Smce Its rev1val m recent ears, it has already played such an important part in

i'oad locomotion, and is probably destined to play a. much greater ~rt, that a few facts concerning It may well be brought forward. The action of the pneumatic tyre is really two-fold; it not only interposes the desired elastic o~shion between th~ irregula: roa.d and the vehicle, but 1t does so by a contmuons sprmg of com­~ressed air, extending round the periphery of the wheel. This air, when once compressed by the load being placed

E N G I N E E R I N G. 599 neers a few years ngo. * These trials were conducted for pneumatic is made clear." It is interesting to note, all kinds of load, in all kinds of weather, upon varied as confirming this statement, that it was recorded in kinds of road, and at various speeds, and though it would the automotor journals that during the recent heavy require a separate paper to deal with them adequately, snow and bad weather, automobilis ts were able, to the general conclusions may be briefly summarised as their great delight, to use their vehicles freely, the follows : pneumatic tyres appearing to be almost unaffected by the

1. The force required for the pneumatic ty re increases bad state of the roads. In addition to the numerical very little from walking to trotting, while that absorbed results obtained by M. Miohelin, a. series of graphic by an iron tyre percepta.bly increasos with the speed. records were obtained from the body of the vehicle, which

2. The advantage of the pneumatic over the iron in- explains to the eye at once, better than any figures, the creases rapidly as the speed increase~. Taking 100 as the reason of the satisfactory results obtained by the pneuma­force required for the pneumatic tyre and iron tyre at a tic tyre. One or two of these are reproduced in F1gs. 14 to slow speed, the resis tance of the iron tyre increased at an 16, in which the curve traced by the vehicle with iron tyres ordinary trot to 126, and at a quick trot to 164; and meeting an obstacle is shown by a. full line, while the probably if the matter bad been investigated for ordi- behaviour of the vehicle fitted with pneumatic tyres is n&ry speeds of an a.utooar, the relative resistance of the , shown by the dotted line. In these curves, iustead of the

F1(J.10. DU NL OP ( ENGLISH). Ftg.11. MICHELIN ( FRENCH). Fig.1:l. C ALLUS ( FRENCH). Fi[j.13. GOODYEAR (AMERICAN)

' ' . • •

RELATIVE DISPLACEMENT CAUSED AND PNEUMATIC TYRES AT HIGH SPEEDS.

tRON

•

Fig.14. PNEUMATIC

-- ------ ------------------- ----...... -~------- ---- •

•

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Fig.17. L EY LAND.

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PifJ.20. COULTHARD.

upon it, absorbs, so. to speak, the obstacle with only a ~mrarary def~rmat10n _of the elastic covering, so that no ur~ er. work 1s done m the compression of the main ~fnng Itself. ~hoto~aphs have been taken by the author

!'- pn~umatic-tyr_ed wheel passing over obstacles of vartou.s.kmds; and 1b can be seen that, even allowing for ft certain amount of preliminary compression upon the ~t sbrfaoe, how ~mall a. distance the load resting on the

a e ~ been ral8ed, and that the idea. involved in the expressal Ion ".absorbi~g an obstacle, , when the obstacle is a i.{ 1 one, lS pra.cttoally correct.

. any measurements have been made to compare the ~IStanc~ to motion of a. hard tyre with that of the P e~mat1o, but these are nob very useful unless taken a." varymg speeds . . . h u that tli d'ff ' smce Ib IS w en the speed is increased

. e 1 e.rences become most marked. The best and ~ost tnstructtve results are those given by M . Michelin

a paper read before the French Society of Oi vil Engi-

TYPES OF DRIVING WHEELS FOR HEAVY MOTOR VEHICLES .

Fig.18. THORNYCROFT. Fig.19. S INPSO N - BOOMAN .

·- - ·-L.... , --J...I

Pig.:U. SINPSON-BODMAN, Fig.22. BAYLEY •

•

I •

•

I I ' I . I •

•

.J.=•f--J--··= J . .t=._ .b.___. --. --. --1 --1

iron tyre would have been found to rise even more rapidly.

3. The solid indiarubber tyre is better than the iron­tyred wheel in certain oases, especially at the trot if the surface be sticky, very irregular, or <'OYered with' snow · but it becomes inferior to iron if the surface be bard and ~mootb. It never gives a much better result than the uon whe~l, and it always remains vas tly inferior t o the pneumat10. On the other hand, the pneumatic is 50 per cent. better than the iron tyre.

As ~I. Michelin remarks, "It is a curious thing, but we have known many people who have only seen pneumatic ty~es, and who have never tested them, affirm that these th10k tyres must drag heavily. It is specially on bad ground, in mud, in snow, tha.b the advantage of the

* Translated a.nd published in a series of articles in the "Autocar," commencing August 15, 189(>.

sha.rp jump indicating a.. violent shook and loss of power w~10h occurs when tlie uon tyre meets an obstacle it is evident that the pneumatic carries the vehicle over' with an easy and gliding motion. This, which is evident in the small obstacle, Fi~. 14, is much more so in the case of the la.rg~r obstacle, F1g. 15 ; while, when the three obstacles are .mterpo_eed, Fig. 16, the beneficial effect of the pneu­ma.tlO tyre 1s very remarkable.

For heavy traffic, when it is remembered that the load has to .be concentrated upon the point of contact on the per1phery .of four wheels, it is no wonder that the wheels have hitherto been almost entirely made of iron tyr~s. At the first Liverpool. trials of. heavy motor ve~toles great trouble w~ experienced ~th the wheels wh~ch had b~n made m the best posstble manner for ordma.ry _vehicular traffic. In almost all oases the wheels showed s1gns of th_e severe stresses and shocks to which they had oeen subJected, and some of the vehicles utterly

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6oo broke down in consequence. The construction of the wheels themselve3 has latterly been the subject of much careful design on the part of makers of motor vehicles, the wheels having necessarily nob only to bear the ac tual load, but t o transmit tractive force from the motor. Figs. 17 to 22 show some of the wheels which have been specially designed by the makers of motor vehicles. These wheels show in each case the arrangements for driving, and this feature is a vital part of the design of the wheel. The iron portion· has been cross-hatohed in to indicate which is metal and which is wood, and the nat ure of the oonsbruotion will be evident without any detailed de­scription. It may be pointed out that M essrs. Coult­hard use a wheel entirely of iron, Fig. 20, which seemed to give very satisfactory results at the Liverpool trials, where ib mqs t be noted that part of the 40 miles run was over a road paved with cobbles of the sort well known in certain parts of L ancashire, affording a test scarcely to be surpassed in severity. The la,st wheel shown on the series 1s that of M essrs. Bayley, which differs from the other driving wheels in the important detail of beiug coned or dished, Fig. 22. A great deal might be said in considering whether the advantages of a coned wheel for heavy traffic are not more t han counterbalanced by the constant tendency of such wheels to run outwards : since when the axles are horizon tal, they can only be made to r un in a straight line by a certain amount of slipping constant ly going on at the tyre, and a constant outward drag upon the axle. Messrs. Bayley's wheel, however, worked very well at the Liverpool trials and subsequently, which is, after all, the main {>Oint to be considered. There i3 another important pecuharity, and that is that the spur wheel a t tached to the d riving wheel is annular, and is driven by an internal pinion. This affords considerable protection from dust and dirt, and enables the out­side of the annular wheel to be used ,·ery effectively as a b rake wheel encircled by a band brake. The spoke'3 are of oak with ash felloes, the i ron tyre being 5 in. wide. In consequence of the new design and special construc­tion of the wheels adopted by most of the makers. they were enabled to stand much bet ter at the second Liver­pool t rials ; but even in the second report, the j udges wrote in their special conclusions as follows : "The wheels and tyres were generally efficient; but concen­tration of heavy loads upon the present small area of wheel ooRtacb 1s a serious difficulty in the problem of goods transport by motor vehicles, and constitutes the chief mechanical cause of the ~low progre3s ma.de.,

Quite recen tly, one or two makers have been appre­ciating the great .dif?cu~ties of this question, and . have tried to adopt sohd md1a-rubber for tyres ; and Fig. 21 shows Messrs. Simpson and Bodma.n's wheel, in which the india-rubber is sho wn cross-hatched in section, and from which they have obtained very satisfactory results. The action of the solid tyre, however, differ.s _in a most important respect from that of the pnenmatiC, viz. , that although deadening shocks, there must al~ays be a great loss of ~nergy coneequen t upon the con~mual expansion of the d tfferen t parts of the s~bstance Itse~f, which is totally d ifferent. from the behaytou~ ~f the at~­cushion in the pneumattc tyre. In Mtchehn s expert­menta the solid india.-rubber sh owed itself always greatly inferior to the l>neumatic tyre, and under some ci r­cumstances infen or to the iron tyre itself . . It was put into competition with the pneumatic tyre m the early days of the cycle, and in that competition has disappeared for ever. The same process of competition . seems to be going on in the case of t he light mot~r vehiCle, though the difficulties are more than proporttonally greater as the load upon each tyre increases. In thi!:i co~mtry, ~he Dunlop Company have been for years a t work tmprovmg the tyres for motor vehicles, and the sectio.n of their latest production is shown in Fig. 10. I t will be seen that the tread has been made thicker w.here the great~st wear takes place, and . where there 1s t~e most lia­bility to puncture, wh1le the ex ternal cu cular form is retained. It is found necessary to ~se t.he very best india-rubber for the external P<?rt10n, I.n order to admit of the necessa.ry deformat10n, whilst the inner par t of the body of the on ter tu be has ~o be strengthened by means of layers of woven can vas m ser ­tion The steel rim on the wheels holds the two enlarged edg~s of the outer covering of. the ty~e, .so that wh~n the inner tube is inflated the tyre 1s bel~ 1.n tts place wtt~out the necessi ty for any internal wtrmg o~ fastemngs. Special machinery i3 required to make this tyre at all cheaply; but this Messrs. D unlop .are now put~mg down, and 1t is hoped t hat the pneum~tiC tyre f~r hgb~ mot~r vehicles will before long be obtamed at pnc~ wh10h w11l enable it to be universally placed on such vehicles.

F ig. 11 shows a section of t h.e Mi_ohelin tyre ; an~. it is interesting to note that M . Mwhelm, who, as .he n~Iv~ly remarks, commenced h is research. on ~he subJect with the object of proving tha:t the Enghs h.dtd not ~ow possess the monopoly for makmg pneum~t~c ty res,. has now succeeded in producing tyres that, 1t 1s only ~Ight ~o sa~, are referred by many users. c;>f motor . v~htcles m this cou!try. This is not so surprismg when It !B remembered that the French have been far ahead of us m the p r?duo­t ion of ligh t motor. vehicles, and the demand for suitable t res for such vehtole8 has been ver.Y keenly .felt .. The d alluR which is also a F rench tyre, 18 shown 1n Fig. 12, and is' seen to be almost iden tical wi th the Dunlop. tyre, exce t that in the important matter of .tr~ad th~re IS not s~ m~ch extra thickne3S allowed, and 1t 18 obvious that the Dunlop tyre 'Yould carry a much greater load as well as have a longer hfe. . . t

The Goodyear, F ig. 13, w~ich 1s a!?- Amer1o~n yre, di ffers from the three ~recedi~g ones tn th~t, hke mo~t American tyres, there 18 no muer t~be, ne.1ther . does 1t de end at all for attachment to the nm by mflat10n, l:>ut is held on by means of small screws, the nu~s for wh10h are inserted in the body of the tyre. There 18 not much

E N G I N E E R I N G. appreciable difference of th ickness for the tread of this type, whir h is circular in section, but it is sufficiently thwk for all practical pur posss.

With heavy traffic, where noise and vibration are not so fa tal to success as in the case of pleasure vehicles, the importance of having pneumatic tyres cannot be said to be so great. On the other hand, it becomes of more im­portance to carry if possible a heavy load easily over an obataole without shock than a light one, as the destructive effect on the vehicle of the inequalit ies of the road is naturally ~reater. This problem of spring wheels in con­nection w1th road locomotion is one which has exercised makers of traction engines for many years, but ten years ago it ws.s stated,* "The exertions of inventors during tl:ie last quarter of a century seem to have been inade­qua te to the p roduction of a wheel with elastic tread, which will satisfy all the complex and moat difficult con­ditions governing the nse of traction engine wheels. Not a few of the most eminent and successful makers of trac­tion engines havf\ abandoned elastic wheels altogether, and resorted to springs between the main axle and the eng ine, and they have, on the whole, been successful. " In spite of this, however, when one looks at the original design of Thompson's wheel in his patent, one cannot help feeling that he understood what was required; and that al though the practical difficulties may be great, there are no mechanical impossibilities in the prod uction of a pneumatic tyre for the very heaviest vehicular traffic. With any existing system, in which four wheels are used, the problem is a difficult one, because of the concentra­t ion of the loads upon such a limi ted area of support. The pneumatic tyre, however, extends this area of resistance by yielding, so that t he area in con ta-ct is much greater than in the case of an iron-rimmed wheel, especially when running over sets or hard ground. Beyond this, it is quite con~eivable that, just as in railways the number of wheels has been largely increased un til a modern bogie carriage has commonly t welve wheels suppor ting it, it may be found economical t o support a motor vehicle also upon a much greater number than a t present.

(To be continued. )

THE PHYSICAL SOCIETY. AT the meeting of the Physical Society , held by the

invitation of Sir Norman Locky~r, F .R.S., in the Solar Physics Obser vatory, South Kensington, on F riday, April 27, Mr. T. H . Blakesley, Vice-Presiden t, in the chair, Sir Norman Lockyer gave '' A Short A cco'W1tt of the Physical P1·oblems now being investigated at the Solcw Physics Obse1·vatory and their A st1·onomical Applications." The chief work carried on at the obser vatory is the com­parison of stellar spectra with spectra obtained from lights emi t ted by laboratory sources. The light from a star (or the sun) and from an arc (or a spark) are focussed alternately upon the t~lib of a spectroscope, and the two spectra. are photographed side by side upon the same plate. The number of lines in the arc spectrum depends upon which par~ of the arc is focussed on the slit . The image of the centre is rich in line.s, the image of the edge gives a few single lines. Changes in spectra are also dealt with. The thickening and thinning of lines de­pends upon several things. In the first place it depends upon the density of the substance, and thus the hydrogen lines in the spectrum of Sirius are much broader than those in a Cygni, the hydrogen being denser in the former star. Changes may also be produced by variations in quan tity. A reduction in the quantity of a t~ubstance generally simplifies its spectrum, the longest line dis­appearing last. The motion of a luminous body to or from the spectroscope alters the wave length of the light emitted, and prod uces a shift in the lines of the spectrum. The amount of deviation is a measure of the velocity of approach. ~n the case of Nova Auri~ae we _ha.ve dar)< and bright hnes of the same substance side by stde. Tlus shows that there are two bodies involved, moving wi th different velocities, the one giving a. radiation and t he other an absorption spectrum. A nother ohang~ in the lines depends upon temperature. In general an 1~crea.se in temperature produces a greater number of hn&a, a notable exce(>tion being sodium, which gives its full number of hoes ab the temperature of an ordinary B unsen flame. T he spectra of metals ob tained from the arc and by sparking are often quite d i ff~ren t. Those lines which make their appearance or are mten­sif1ed in passing from the arc to the higher tempera­ture of the spark are known as enhanced lines. The comparison of stell~r spectra with laborat?ry svectra. is often easy. F or mstance, the p resence of tron m the sun and hydrogen in S irius. is easily seen. Several lines in the spectrum of ;B.ellatn x hav~ been s~own to be d ue to helium, the pos1t1on of the hoes bemg exactly the same as those d ue to the gases from Clevite. In many cases it is possible to build up the spectrum of a sta.r from the spectra of its constituen ts taken at the pr?p~r temperatures. F or instance, the spectrum of i' On oms can be closely imitated by means of oxygen, nitrogen, and carbon, together with the well-ma.rked lines of hydrogen and helium. W e can roughly estimate, by the character of the spectra of stars, the temperature of thos~ stars1 aad thus arrive at a stellar thermometry. Star tmg wtth a. hot star, like :Bellntrix, and passing through f:J P ersei, 'Y L yrae Sirius, Oastor, Prooyon to A rcturus, a cold star, we hav~ a gra~ual change in the character . of the lines which appear m the spectrum of any constituen t. T he widening of the lines 10 the case of spectra of sun spots enables us to trace changes in temperature of the sun, and can compare these temperat ure changes wi th a variety of terrestrial phenomena, such as var iation in latitude. The extraordinary number of lines exhibited by many metals suguests that what we are accustomed to call

* T he Engineer, December 12, 1890, page 469.

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[MAY 4, I goo.

chemical elements are really complex bodies which are made up of simpler ones. A t tempts have been made to build up the spectra of metals by superimposing simple sets of lines upon one another. In many oases a great number of serie~ would be required to represent things completely. In the cage of hydro~en it would be neces­sary to have a t least 27 series to give the structure spec­t rum only. Taking the atomic weight of hydrogen as unity, the atomic weight of the little masses which might ~ive rise to any one of the series would be about .0019. This i3 of the order of magnitude of the small bodies, whose existence has been suggested by Professor J. J. Thompson from his work on ions.

LAUNCHES AND TRIAL TRIPS. MEssRs. Short Brothers, Sunderland, launched, on the

11th ult., a steamer of about 6000 tons CELpacity, which they have built for the Prince Line of steamers, Newcastle-on-Tyne. This steamer is of the following dimenaions : Length over all, 363 ft. ; breadth, 45 ft. ; and dept h moulded 27 ft. 9 in. The vessel is divided by six watertight bulkhead~, forming four large cargo holds. The vessel was named Norman Prince. She is to be fi tted by the North-E astern Marine E ngineering Company, Limited, of Sunderland, with engines having cylinders 24~ in., 40 in. and 66 in. in diameter, with a. stroke of 45 10., steam being supplied by two large steel boilers, working at 180 lb. pressure.

The s.s. Firda wen t out on trial from the River Tees on Tuesdar., the 17th ult. She was built by the F evig Shipbmlding Yard, of Arendal, Norway, for B.Pecial ear­vice as a passenger boat among the Norweg1an fjords, and was towed across to the Tees to receive her machi­nery, which is supplied by Messrs. S ir Christopher F ur· ness, W estgarth, and Co., L imi ted. The engines have cylinders 16~ in., 27 in., and 44 in. in diameter by 30 in. strokE', with an extra large steel boiler which supplies steam ab 175lb. pressure. On the trial trip the machinery generated between 700 and 800 indicaood horse-power, and the vessel maintained an average speed of 13 knots.

Messrs. R opner and Son, Stockton-on-Tees, launched, on the 17th ult. a. steel screw steamer of the following dimensions, vi~. : Length between perP.endiculart~, 277 ft . 9 in. ; bread th extreme, 39 ft. 6 m. ; depth moulded 19 ft. 2 in. She has been built to the order of Messrs. 'R. R opner and Co., W est Hartlepool. The vessel will carry about 3100 tons deadweighb on Lloyd's freeboard. She will be fi tted with a set of triple­expansion engines by Me.~rs. Blair and Co.? Limited,, of about 800 indicated horse-power, steam bemg supphed by two steel boilers 12 ft . 6 in. by 10 ft., with a working pressure of 160 lb. Tbe ves~el was named Glenby.

On A pril18 there was launched from the shipbuilding yard of Messrs. David and William Hend~rson and Co. , P artiok, a steel screw cattle steamer, wh10h they ~ave built to the order of Messrs. Lamport and Holt, LIVer· pool for their Sou th A merican trade. The vessel is 405 ft. long between perpendiculars by 52ft. broad and 31ft. deep. A seb of triple-expansion engines, with cy. linders 29~ in., 47 in., and 78 in. in diameter by 4ft. 6 in. stroke, and three single-ended boilers construct~d for a. working pressure of 200 lb, have been supphed and fit ted aboard by the builders. On leaving the ways the vessel was named the R aeburn.

Messrs. Mackie and Tuomson, Gova.n, launched on the 18th ult. the Y ukon, a. steam trawler of about 180 tons, which they have buil t for Mr. Thomas H amling, Hull. The vessel is 132 ft . long over all, and 125 ft. between perpendiculars ; her bread.th is 21ft. ~ in., a~d her ~epth (moulded} 12ft. 3 in. Tnple-expans10n engmes wt~l be supplied by Mr. W . . V . V: Ltdgerwo~d, . Coa:tbr1dge. The cylinders are 13 m, 22 10. , and 36 m. m d1ameter, by a stroke of 24 in.

The Ardrossan D ry D ock and Shipbuilding .Company, Limited, launched on the 18th ult. from thetr yard ab Ardrossan a steel screw quarter-deck ca.r~o steamer, built to the order of Messrs. Ma.nn, Macnelll, and Co., Hope-street, GlaQgow, ~nd intended for the general coasting trade. D 1 mens10ns : Length between perpen­diculars, 135ft.; breadth m<?ulded, 2~ ft.; depth moulded, 10 fb. 9 in. She has a carrymg capacity of 375 tons. The vessel was named the Glassford.

Messrs. Da.vid and William H enderson and Co., Par­tick launched on the 18th ult. a steel screw cattle steamer whi~h they have built to the ~rder of Messr~. Lamport and H olb, Liverpool, for thetr South ~mertcan t rade. T he vAssal is 405 ft. long between perpend10ul8:'rs, by ~2 fb. broad and 31ft. deep. A set of triple-expanston engmes, with ~ylinders 29~ in., 47 in., and 78 in. in diameter by 4 ft. 6 in. stroke, and three single-ended boilers con­structed for a working pressure of. 200 lb., have been supplied and fitted aboard by the bmlders.

The steel screw steamer Lucia, built by Mess~. Craig! Taylor, and Co., Stockton-on-Tees, for ~essr~. Fra.telh Cosulioh, T rieste, left the Tees for ~er tr~al tri.P on ~he 28th ult . The vessel is of the followmg dtmens10ns, vtz. : 290 ft. by 42 ft. 6 in. by 18 f t. 10 in. mou.lded. She ~as large centre deckhouse for acoommodat10n of oaptam, officers, &c., water ballast in double bottom fore .and afb and in peaks. She carries over 3300 .tons deadwetghb on a light draught of water. The engmes ar~ by Me~rs. MacColl and P ollock, Sunderland, the ~Y hndera bei.ng 21 in. , 35 in., and 57 in. in diameter by 39 m. stroke, Wl th t wo large boilers wol'king at 160 lb. presEure.

MAY 4· 1900.]

GRAPHICAL CONSTRUCTIONS IN ENGINEERING.*

By F. H. HuY~EL (of Ma..qon University College, Bir­mmgham}, Assoc. 1\ti.I.C.E.

THE profession of engineering is one ~hi~h P.robably requires even with the amount of speo1a.hsa.t10n that we now have a wider knowledge than any other.

Over and ~bove special talents and abilities, the actual knowledge of a thoroughly and completely successft.l engineer has to be very comprehensive. It can be divided roughly into three parts:

1. Commermal knowledge. . 2. Technical knowledge from experience. 3 Scientific knowledge. The first of these is so completely outSide the scope of

this paper that it ca.nnot . be more than . mentioned here. It becomes a. necess1ty dueotly the engmeer has to con­sider questions of finance, purchase, investment, depre­oia.tion, and to a. large ~xtent employment and ID;a.nage­ment, and such quest10ns are, of course, contmually

• occurr10g. . . . . Under the term experience, 1s moluded all that va.r1ed

knowledge of material, methods and form, accumulated a.s a. result of the failures as well as the successes of our predecessors and our3el \'es, It enables a.n engineer to act quickly and with certainty, to anticipate difficulties and to meet them successfully, because he is able to recall the material and form of a. part successfully used or method employed under similar circumstances. Such a. know­ledge, however, whilst absol!Jt~ly necessary. to every engineer depends upon existmg constructiOns, and cannot therefore depart without risk very far from such. It is a. proportionate n.nd qualit~tive knowledge, ~nd directly a. totally new prob~em a.r1ses, or a. constructi~n is to be made on a totally different scale, or a. ma.teru~l to be used under entirely different circumstances, we must have a quantitative knowledge of thE' actions occur­ring, and must know pr~cis.ely t.he effect ~f such ~~ the material employed. This 1mphes .the. thud req~nstte­a scientific knowledge, the use ef smenttfic reasonmg and theory. . . .

That reasomng lS necessary m such a. case cannot be denied. Directly we get to a. point where we cannot appeal to direct experimental fact, the conclusion must be reasoned out, and the process and method of that reasoning constitute a. theory; and it. is i_n these freque~t and all-important cases that soon~ s~1ent1fic kn~wl.edge 1s essential. Nor by any means IS Its value limited to such cases ; the scientific spirit should pervade every branch of the engin~er's ~ork1 his experien~e should be gained and recorded m a smentific way, and hlS commerce conducted as far as possible on scientific lines.

This paper deals only with a. certain aspect of this scientific method, viz., tha.t in which the reasoning is assisted and the results obtained by graphical construc­tions instead of ordinary symbols.

Passing to the purely scientific side of engineering, we find that it consists of a. knowledge of properties of matter a.s given by phyaics, chemistry, &c., and thE:' method of reasoning, by means of which these sciences have been developed.

By far the most important branch of physics to the en­gineer is tha.t which deals with motion and the relation of force to motion, viz., dynamics, and it is because the fundamental quantities of dynamics (or mechanics, as it is less properly called) can be easily represented on paper that graphical methods have become of such importance to enginee~.

It is not this alone, however, for mathematics in many ways lends itself to graphi('.al treatment, and a.ga.in one important property of matter, viz., form, with which we have a great deal to do is essentially graphical, constitut­ing the science of geometry.

To pub this concisely, we may say that geomet ry, mathematics, and mechanics, constituting as they do a. very large part of an engineer's scientific knowledge, all lend themselves to graphical treatment more or less readily in a. manner to be indicated later.

The following is a classified list of the general problems in these sciences which permit of graphical treatment :

1. Geomet-ry.-Problems relating to form, areas, lines, volumes, and all properties of same, centres of gravity, moduli of inertia, &c., ratios, and simple, algebraic, and arithmetical operations depending \!POD ratios.

2. Motion introduced to forruer. - Kinematics, diagrams of position ab different times, point paths, centrodes, &c.

3. Mechanics. - Velocities and forc63 represented by lines, and all properties and relations of same.

4. !Jfathe111;atics (Graphical). - Co-ordinate geometry. Representa.tlt>n of equations as curves and determination of area. slope, max1ma and minima, and their varied meanings. (Diffn. and Into.)

4a. lnver&e of Forme1·.-Plotting of experimental re­ault.s, and determination of law.

The idea of motion is introduced with great a.dvanta~e mto geometry, not only for the solution of problems m Cla.ss 2 above, but into the actual definitions themselv~.

An angle is no longer the inclination of one line to ~nether,, but is the amount of turning a. line undergoes m rotating from one position to another. This definition at on~e enables us to distinguish between positive and negative an.gles, .according to the direction of rotation of the revolvmg hne. A counter-clockwiee rotation is alway.s considered positive and a. clockwise rotation, negat1 ve, a!Jd the same applies to the angles. . An. area. 18. a. space enclosed by a line, and the enclosing

bne .18 de.qcrib~d by a moving point, and again the intro­ductiOn of motton enables us to consider the area. positive

* ~a8pe~ read before the Civil and Mechanical Engi­neers o01ety.

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E N G I N E E R I N G.

or negative, according to the direction in which the boundary is described.

The above rule, as to sign, is the same in this case ; t~at is, if the direction of the boundary is oounter-clockw1se, the area is positive ; if clockwise, negative. This ma~ be stated in a slightly different and rather more convement way, thus : If on entering the area. the boundary passes from left to right the area. is positivet if it passes from right to left, negative; and as the oounda.ry is all in one direction, it is of no consequence a.t what point you cross the boundary.

Looped Figures.-Fig. 1, page 602, shows a.n indicator diagram with a loop, and we know by interpreting its meaning that the part AB E C (hatched from rtght to left) represents work done by the steam on the piston, and that the parb AD E C (hatched from left to right} repre­sen ts work done by the piston on the steam; the available work per stroke is therefore the difference between these two areas. Subtracting, the oross-ha.tc~ed part disappears and we have left the area M represe(lting positive work and the area. N nega.ti ve work, P.ad the area of the d1 ~ram giving the available work dAne on piston is M-N. Thts we see from the meaning of the diagram, but we can also give the boundary a. direction indicated by the arrow­heads in the figure, and applying the above rule we see that on entering M the boundary passes from left to right, and the area. is therefore positive, and N in a similar way negative. The area by this rule is therefore M-N, and in agreement with what we have previously determined.*

With any other figure the same, the quadrilateral A B CD in Fig. 2a has a.n area equal to CB F-A F D, and if we mnke for this figure the elementary construction for reducing a quadrilateral to a triangle of equal area., it can be shown by simple geometry that the triangle so obtained is equal in area. to the difference, not the sum, of the component triangles. In Fig. 2 an ordinary quadrilateral is shown, and the construction for reducing this and the cross-quadrilateral (Fig. 2a,) to triangles equal to them in area. in each case can be followed step by step. It is as follows: Join A C, through B draw a. line parallel to A C to meet AD (produced if nece~sary} in E ; then the triangle E C D is in each case equal to the quadrilateral. It will be noticed that in Fig. 2a, the triangle is very small, and, as it has already been stated, it is extremely easy to prove that it is equal to 0 B F -A F D. This is introduced in order to show that there is nothing in the least artificial about the definition given, but that the~ are really involved in all geometrical con­structions. This is a.ga.in evident from the fact that if a. planimeter (an instrument which mechanically records area.) be taken round an area such as 2 (a}, the reading obtained will again be the difference of the component triangles.

L et us now consider Fig. 3, the arrowheads as before denotin~ the direction in which it was drawn. The part C 1s obviously positive, and the part A (the boun­dary of which also passes from left to right) cannot be entered exce\)t from the positive area. C; it is, therefore, doubly positive, that is to say, it is positive and counts twice. The part B, on the other hand, is negative, con­sidered by itself, but as it is entered from the positive area 0, the signs cancel one another, and the result is that it does not count in the area at all.

Another way of looking a.t this is to notice that the outside lbounda.ry being from left to right makes every­thing within it positive. The part A is, therefore, positive, because it is within the outer boundary and positive again because of its own boundary direction, i.e., twice positive, whereas the part B is positive for the first of above reasons and negative for the second, and, there­fore, disappears.

A pla.mmeter taken right round the boundarr of a figure of this kind gave its area as 10.29 square mches. Part C had a.n area 8. 68 square inches, A = 0. 785 sq ua.re in.che!'t and 2 A + C.= 10.25 square inches in agreement with tne above value.

Referring briefly to Fig. 4, its parts are evaluated in the same way as before, by crossing a. succBSSion of boundaries and noting the sign of each. Thus the part marked A is + and must be reckoned three times, and this re~mlt is ob­tained whether the path be that marked 1, 2, 3, or a~y other.

These considerations are really of some importance practically, because a.t any time we might be called upon to analyse a. diagram drawn automatically by some motor or other machine when it would be very necessary to distinguish between the + or - parts of the area..

We must now return, for a. short time, to our general considerations. We have analysed the engineering scientific knowledge and noticed those parts which lend them­selves to graphical treatment!, and something about such construction must now be said.

By a graehical construction is meant one in which paper, pen01l, and drawing instruments are used to make an actual quantitative determination - to obtain a numerical result, or a definite point, line, or figure.

Such a process is of necessity limited in its accuracy, but is quite within the range of accuracy req_uired by en~neers. In every engineering problem certam forces, we1ghts, or stres~es, have to be estimated or measured, and the variation in material or conditions of use make these detel'minations vary in ordinary work to the e:<tent of 3 per cent. or 4 per cent. ; in some cases very much more, in others it may be a. little less.

It is not necessary, therefore, that a.ny work ba.sed

* If the arrowheads had been put on in the other direc­tion, the area would have been M - N; but this is of no importance, because all we wish to know is the relative values of the parts of which the figure ia composed, and whether we consider the whole as positive or negative is of no consequence .

6o1 •

upon such data sh_ould be carried out ';Vith a.~y greater accuracy; a. complicated problem can w1~h <?rd_ma.ry care be worked out graphically well under thts bm1t of accu-racy. . 11 ·

Even when the working out mvol ves aotua Y approxi-mate constructions, <J.Uite distinct from former. the accu­racy obtained is suffiment.

A line of any length can be drawn accurately to, sa.y, -ttr in., and, therefore, as far as le~gths are con~erned, any degree of accura.oy may be obta.med by ~hoo~mg a la..r~e enough scale. Other operations ooourrm~ m graph.10al constructions are (1) drawing of parallel hnes and hnes making given angles with one another. The parallels can be drawn perfectly accurately, but the accuracy of the latter depends upon the exa~t location of ~he intersection of two lines or arcs, and thiS, when the hnes make very small an~les with each other, may introduce an error.

An es timation of the magnitude of this error has been made by means of Fig. 5, the construction being that for the bi-section of a.n angle, with the a.ros a a, b b purpose1y chosen of very long radius. .

The error in the bisection of the angle due to d1fficulty in location of point of intersection was found to be 2.1 per cent., the actual displacement of the point of intersectiOn from its true positiOn being 0.03 in., and the angle be­tween the arcs being about 5 de.g. The latter is about as small, therefore, as should be used in constructions where moderate accuracy is required.

The errors found above, and those to be given subse­quently, are the maximum errors found by four draughts­men working independently, and not taking any special pains to obtain accurate results.

They represent, therefore, the greatest, but always pos­sible~ errora likely to be found in the particular oases to whion they refer with ordinary careful work.

Another important operation frequently occurring is that of drawing a. tangent to a curve from a given point, and the location of the tangent point. This can be done with great accuracy, the error in the angle a. (Fig. 6} not being measurable, and the error in AB being only 0.5 per cent., viz., 4.58 in. instead of 4.60 in.

A third important operation is that of drawing a tan­gent to a curve at a point, and this, when the centre of curvature is unknown, is difficult.

To determine the error in this a parabola was plotted and then drawn in by hand: three points were taken on it and tangents ruled in by eye a.t each of them. The angles made by these tangents with the horizontal were measured and also calculated, and the errors proved to be 5 per cen b. , 2.4 per cent., and 1. 7 per cent. respec­tively. The 5 per cent., of courae, occurred where the curvature wa~ greatest, the radius of curvature a.b the point being about 1~ in. It seems therefore that a con­struction involving this operation should be used with caution or, if possible, avoided.

Of the actual approximate constructions, the most important is that of drawing a. line equal to an arc. To do this, a tangent is drawn at one end of the arc, and, starting at the other extremity, small distances are stepped off until a point is reached which may be con­sidered as either on the arc or tangent, the number of intervals stepped along the arc is then stepped off along the tangent, and the length of the tan­gent so found will b6 sensibly equal to the length of the arc. The error is sma1ler than would be ex­pected. Arcs subtending 45 deg. in circles of 1-in., 2-in., and 3-in. radius respectively were estimated in this way, and in each case the error was less than 1 per cent. There is no gain in accuracy by taking the steps very small; a. length of arc subtending about 5 deg. is the best.

To comJ?lete this investigation into the errors occurring in gra.pb1cal constructions, two examples involving several of the above operations have been considered.

1. The area of a triangle by the method shown in Fig. 7. The triangle is A B C ; from one corner A an arc of

ra.dius 2 units is drawn, and from one of the remaining points C a tangent CD to this aro is drawn. From the remaining corner B a line B E parallel to C ·D is drawn to meet A C in E. Then the number of units of length in BE is equal to the numbel' of squa.ru 11nits of area in the triangle AB C. (The unit must be chosen so that the point 0 falls without the circle, otherwise the con­strucpion fails.)

This construction involves the measurement of five lengths, two intersections, and a. parallel. An example worked out gave an area of 1.40 square inches, instead of 1.43 square inches, i.e. , a.n error of 2 per cent. The errors are not cumulative. In this ca.&e the time of each method was taken, the graphical construction required 1! mi-nutes, the calculation by the ~s(s - a ) (s - b) (s-e) formula. took 4; minutes.

2. The positiOn of the mass centre of a. sector was also worked out. The construction involves the measurement of several lengths, determination of several intersections and one arc approximation, the result was right to 1 pe~ cent.

We have already seen that almost any problem in science is capable of a graphical solution, but it is by no means the most suitable in a. large number of cases. When these methods were beginning to be understood and used, there was a great tendency to push them too far and apply them to the solution of proolems far more easily done in other ways.

We may take it that for one method to supersede another, it must either be (1) quicker, (2) present the problem more simply an~ clearlr, and ~o prevent un­necessa.~y thought and ~1sta.kes m workmg, (3} or give results m a more convement form, and the two classes of problems in which graphical methods possess some or all. of these advantages are tho~e in whi~h (1) lines or pomts are found to fulfil certam conditiOns and con­nected by a curve the geometrical properties of which are

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6o2 :

translated; (2) problems which can be solved by operat­ing with straight lines of definite magnitude, direction, and position.

For instance, if we are given a set of forces acting on a structure, say, a girder, we can by a sim~le construc­tion of the second kind involving the properties of fore~, draw a bending moment diagram. Th~ ordinate of this diagram gives at any section a measure of the tendency of the forces to rotate the part of the girder on one side of the section relatively to that on the other.

Having obtained this diae-ram, we can by a not very difficult process of the first kmd, deduce from it a second figur~, the ordinate of which will exhibit to a scale, de­pending upon the material and section of the girder, the alope of the deflected girder at every p oint, and by re­peating the process on this new figure, we can obtain a third, which is the actual form taken by the deflected

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E N G I N E E R I N G.

passing throu~h the centre of gravity of a given section. Let the directiOn be X Y. Draw a line X Y in this direc­tion, and touching the base of the figure.* Next draw an axis X X at right angles to this. In most practical .Problems the section will be symmetrical, and in thts case the line X X is naturally taken alo11g the axis of symmetry, the construction has then only to be made for one-half of the figure; if it is not symmetrical, the axis •X X, oan be drawn in any con­venient p osition, and the following construction must be applied t o ea.oh side of the figure. Dra\V a line XI yl parallel to X Y about half-way up the figure, and at some even distance "d " from X Y.

Next draw a series of lines Pp parallel to X Y . In straight parts of the section, such as the web in the figure, these can be wide apart; where the section changes rapidly they must be drawn olos~r together, in order

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The value of a section to resist bending or twisting depends upon its moment of inertia about an axis through its centre of gravity. Every problem in which rotating bodies are concerned, flywheels, &c., involves its nse.

The usual construction for t his necessitates the finding of two centres of gravity; the one now given determines the moment of inertia as an area direct, only a planimeter being required.

.Referrmg to Fig. 9, X Y is the ax is about which the moment of inertia is required, and X 2 q is a line at right angles, if possible, an axis of symmetry for the same reason as m the last construction. Above and below X Y two lines X 1 Y 1 and X 2 Y 2 are drawn eara.llel to it, and situated at some exact distance cl from it. Next draw a series of lines Q P parallel to X Y across the section, and in each case set off X 1 q = X Q. Join q P, and produce, if necessary, to cub X 1 Y 1 in r. Join r to X, cutting

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girder under the given loads. This is mentioned merely as an example, introducing both the important meth<?ds mentioned above, a.nd into one or other of these classes, v~z., geometry (including co-ordinate geometry),, or mecham~, a.ll the engineering problems treated graphiCally fall.

The following examples are chosen because the con­structions do not seem to be as well known as .they should, and also because they soh ·e problems wh10h. are not p ossible of solution in any other but the ~raph10al way, except direct experiment, the ~a.tter bemg, however, n either so accurate nor so convement. .

BE U'l/ inches = ctrefk of ABC~Sq..lns. (S28G. G) sect:./.,cro a.houtJXY- CX/ cL:1:

tha.t the final curve may be quite definite. At the point P whore one of these li~es cuts ~he section, draw a line P Q parallel to X X, mtersect~ng X 1 YJ ~t Q J oin X and Q and produce to p on the hne ~ p or1g-~nally drawn. p is a. point on .the curye we are findmg. ~epeat this for each of the sen es of hnes and connect p om ts p so found by a. curve (dotted in the figure).

T hen if the area of original fi~ure = A, and the area of new dotted figure = a, the distance of the centre of

gravity from X Y along X X = K d.

Q P in p (in this case X r is produced). Then p is a. point on the required curve.

Repeat this for each of the lines drawn across the sec­tion, for lines below X Y using the lower parallel ~2 Y 2,

and join a,ll the points so found by a curve (dotted m the figure).

L et the total area. of this dotted curve = a . Then moment of inertia of section about X Y = a d2•

The construction permits of many variations, e g., the Qew area. can be obtamed by using only one parallel; but the construction as given above will probably be found the moat useful and nccura.te. The first construction is that for the centre of graVlty

of an irregular section. As to the value of th~s point, ~t is well known to .a.ll;

any question of balance mvolves It, and so do questiOns of stability and buoyancy. . It m.ust be. ~nown for. a.ll sections subjected to bendm~-gtrder, JOist, or ratl­and in 'an riveted work the rivets musb, as. far as ~os­sible, be arranged symmetr~cally aboot a. .ltne passmg through the centre of gravity of the sectiOn, a.ng~e or other shaped iron used. There arfj several constru?tions, but the one shown in diagram is incomparably Simpler and neater than any other of which the author knows.

The construction is shown in Fi~. 8.. The. probl~m u~u­ally takes the form of finding a hne m a. g1ven dLrect10n

If X X is not an axis of symmetry the a.rea a must be taken as the sum of the areas of the new curves obtained for both sides, and A must be the are~ of t~e entire section. Modifications of this constructiOn will suggest themselves, and compared wit~ the method of dividing the section into s trips and findmg the resultant of a number of forces considered a~ the weights or areas of the strips, the construction above will be found most expeditious.

The next construction is for determining the moment of inertia of a section. This is also of the utmost importance. -

* If the figure is curved at the bottom, the line X Y must be a. b ngent at the lowest point of figure.

When the construction is made in connection with a

bending problem, for which f = ~ .u [these lettera

having their usual meanings], the distance d may be

taken equal to y, in which ca.so I = a y2 and f = }rf. ay

* The axis X Y usually divides the length of th~ sec­tion ab unequally and about the best value ford IS the length of the shorter of these segments X a in the figure. These lines X 1 Y 1 and X~ Y 2 may or may not cut the section.

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MAY 4· 1900.]

"ENGINEERING" ILLUSTRATED PATENT RECORD.

COMPILED BY w. LLOYD WISE. IBLBO'I_'KD_ J.BBTRAOTS OF RBOBNT PUBLISHED BPEOIFIO.ATIONS

OBDBR THB AOTB 1888- 1888. T¥ numbefo of 1Mws given in the Specijicat:ihtl Drawings i8 stated

•n ~ C<Ut; whiTe notu are tMnttooe(t the S"'ecin"at•on .;, not illmtrattd. ' r ~- .. ...,

WM1'6 inventions .are comnumica.ted f-ram abroad the :N a mu d: of. the Comm~nt~tors are given in italics. ' ' c. •

Copta of Specijication8 may be obtained at the Patent 01/lce Sale Bra~, 16, S~thampton Buildings Chancery-lane fY.C at the uniform p~ of Bd. ' ' · ·•

The ~te oJ. th~ ~vertisement ~f the acceptance OJ a complete Spec&ftcatton u, 'n each case, gtven aJte-r the abstract unless the Patent h~ been seald, when the date of sealing is gi.Jen

Any p6rson !nay at any time within two months from th~ date of th;t advet:tt:Sem6nt of the acuptance of a. complete Specification g'~ not~ at the Patent 01/ice of oppoB-ition to the grant of~ Patent on anv of the ground:s mentioned in the .Act.

ELEC"l'RICAL APP A1tA. TUS.

4801. J. B. Bolmea aDd F. Broadbent Newcastle Beslstan~e. Swt~h~s. [11 ~B.] March' •, 1899.-Th~ object of this mventu;m IS to provide an apparatus whereby the !Dotor or other oirowt can pe closed through a resiato.nce which 1e then gradually automatically out out . For this purpose a rheoetat contact ~rm, moved by the ope~ator, ia ado.pted to be wo!ked over a ~enee of c~mtaots arranged m a straight line or in a cucular arc, m a direction to cut resi~tance out of the circuit by a force euch as may be exerted by a sprm.r or weight , and the rate of movement. is co~trolled by a dasbpot escapement, or the like. In combination \nth the rheoatat arm, another movable arm refened to as the switch contact arm, is provided which is 8~ constructed that at one extremity of its ro.nge of 'movement it

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engages with the rheostat arm in such o. manner that when moved by the operator towards the other extremity of its range, it draws the rheostat arm with it, inserting the resistance as it proceeds, and on nearing the end of its travel, olosea the oirouit, and t hen releaees the rheostat arm, which thereupon gradually cuts out the resistance in t he manner already described. The baokward movement of the switch arm, which breaks the circuit, may be etlected either by hand or through the agency of a mechanical or an electromagnetic device which prevents it remaining in a posi­tion intermediate between the extremities of its travel. Auto· matic mechanism le provided which prevents the operator from -opening and closing the switoh when all the resistance i9 cut out, when an excessive current would pass through the motor. (.Ac­cepted. March 21, 1900.)

9612. B. G. I.a.mme, Pittsburg, U.S.A. System of .Eleotrloal Dl.strlbution. [J Fig.) May 5, 1899.-(0onven­-tion date October 6, 1898.)-For the lpurpose of securing a con­stant electromotive force at the terminals of a ~enerator driven at variable speed, the dynamo supplying current is combined with a direct-current generator, driven by an elect ric motor, included in the distributing system, the current supplied by the latter actin~ to reduce the magnetiaaf;ion of the field magnet of the fom1er

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gei!erator. The field magnet of the motor may be either shunt or senes wound, or separately excited ; but whatever be the type of m.oto.r employed, the relation between the field-magnet core and ~nd10g should be such that the former is constantly maintained JD a state of magnetic saturation. A rotary t ransformer may in so~e instances be substituted for the motor , and the generator driyen thereby. The invention is mainly applicable to the regu· latton of eJternating generators supplying t ransformers in parallel;

E N G I N E E R I N G.

~~~~-nu(~~~~ ~'J~!~:~ :~, t~9e0~~fulation of direct-current gene·

6819. W F J Switch • • . ones, Hammersmith. Electric more e es~ [S Ftg~.] March 29, 1899. - This invention relates its mai~~g;~nr .to ~Witches for CO!ltrolling electric motors. and a manner tha~ if~~he ;onsrrucft a swtliOh of this descript ion in' such term· d .· upp Y o current ceases or exceeds a prede· oiroui~e F~axtt~um, the 8\vitch a~tomatically breaks the motor

· r ts purpose the swttch la so arranged t h t th movement of the hnndwheel or lever ie transmitted to the ;wito:

~~~~~J b~~~:J~u~~ri~~ ~~t~~~~Met~~il~uo~~b~v~~~~s: ~:t on o e clutch secured to t he handwheel or le~r being

('119)

mechanically ~eld in the position to which it is tu.rned while its other potti<?n IS held in th~ ~osition by electromo.gn~tic means a!one_. and tB thus automatically released, thereby breaking the c~rowt, as soon as the cunent ceases. The circuit is automa­tically broken when the ourrent supply becomes excessive by ~ean.s of a~ elt:otromagnetio device operated by a coil in the ou ou1t, whtoh ts adapted to short-circuit t he clutch electro­m~net, and thereby. to ~emagnetise the clutch and cause the swttoh to break the OlfOU.tt. The movement of the switch is con­trolled ~Y a; d~hpot, which also provides a blast to rupture the aro which IS hable to be formed when the circuit is broken (Accepted Ma;rch 21, 1900.) ·

1167. A. J. Fabre, Nimes, FraDce. Suspension De.vtce for Elec~ric L~mps. [~ ~s.) January 18,1900.­A B}ngle or doul?le difterential pulley IS JOUrnalled within a hollow ~mg for!Iled 10 two parts, which are screwed together, and pter~ed ~th orltlcea ~or the pa.ssage of the conducting cord. The tnten or of the ca81Di" Is loaded with shot, so that it forms a

Fig. I .

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un

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• balance weight, and the diameters of the barrels of the pulley are so proportioned that this weight is in equilibrium with that of the lamp in all positions. The fom1 of apparatus illust rat.ed in Fig. 1 is generally applied to a single lamp ; that illustrated in Fig. 2 being applicable more especially to the suspension of groups of lamps or single lamps of unusual weight. (.Accepted ilf arch 21, 1900.)

9278. J. G. Statter, WestmiDster. Dynamos. t2 Figs.) May 3, 1899.- This invention relates to the construction of generators an.d JJ?.Otors ha~ing two a~mature~, but only one field magnet, which 18 magnetised by a emgle coil. The magne­tising coil ia wound round on a bobbin and encircles an inner core, having a pair of polar extensions ; it is also enclosed within an annular outer core composed of a pair of semi-cylindrical por·

tions bolted together, and each furnished with a polar extension ; the poles of the inner and outer cores being reepecti vely diago· nally opposite each other. The outer and inner cores may be mechaniCAlly connected by non-magnetic material ; and the con­struction may be modified so that only one armature is used ; and the inner and outer cores and their pole-pieces may be con­structed of any magnetic material, whioh need not be uniform throughout the magnetic oircuit. (.Accepted March 21, 1900.)

6982. G. Marconi and the Wireless Telegraph and Signal CompaDy, Limited, London. Induction CoUs for Wireless Telegraphy. [6 Figs.] Aprill, 1899.­This invention relates to induction coils to be employed as de­scribed in specification No. 12,326, of 1~8. The primary and secondary coils, instead of being wound in single layers, as de­scribed in the above speoi1lcation, are either made very short, or wound in sections ; and the number of turns in the successive

layers of the sec~ndary coil preferably diminish as their diato.nce !rom the c~n~re mcreases, the primary coil being also in some mstances stmtlarly arro.nged. The end of the secondary which is f~rthest away from the nucleus is connected to the sensitive tube dire~tly, a~d not through the condenser. The figures diagro.m· ma.tlco.lly Illustrate the various forms of induction coil, whi<'h, it

- ·- ·-.. - ·-·- ·-is s~ted, have been succe88fully used in wirele88 telegraphy · the particulars of succes~ful coils beine- also ~ven in tables which form part of the specification. The vertical wire usually employed wita these coils is formed of seven etranda of copper wue H O ft. long ~nd about 1 millimetre in diameter, and the top of i bis conductor 18 about 100ft. above the ground. (.Accepted Jla;rch 21, 1900.)

GAS ENGINES, PRODUCERS, BOieDEKS, ~&c.

6525. G. Wanderpepen and A. Van Berokelaer, Br~saels, Belgium. Generating WumtDatlDg Gas. [1 Fi1/·l March 2i, 1899.- Hydrogen is c.renerated by the reaction of actdul~!tted water upon iron, very much in the manner usual in labo~ato~tes, and the hydrogen is subsequently carburetted by passmg 1t t hrough or over naphtha, benzine, or other hydrocar­bon. I t is stated ~hat ~n illuminatini gas of high candle-power m~y be produced m this manner. The apparatus described com­prises a . reservoir sup~lied with water and sulphuric acid, and fitted With o. tube which conducts the acidulated water io the

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lo~er J?art of a hermetically closed veasel, near the bottom of wh1oh 1s arranged a perforated plate of red copper which sup­po_rts the i!On w~cb ren:ots with the dilute acid. The cover of thi? veasel1a furmshed W1th a small hopper mounted on t runnions which . serve.a to reple.nish the yessel with iron. The gae .;ene: rated m th~s .vessel IS SUC?esstvely passed through a pan of ve~ela of BI~~ar construction, fitted with baffles, the first of which, contammg water, serves as a washer, while the second containin~ a hydrocarbon, serves as a oarbutter. In some case~ ~he gener!'tor may advantageously be supplied with iron ore matead of uon. (.Accepted Jlarch 28, 1900.)

770. R. HelD, FrtedeDaU. and T. BabD, Kotzachen• broda, Germany. Gas-Pressure Regulator. £• Figs.) January 12, 1900.-The rressure of the gas ia regulated by means of a valve, the spindle o which is connected to a bell floating in mercury. The gas enters the regulo.tor at the lower side of the casing, and, passing the valve, obtains access to the interior of the

bell, which is t hereby caused to rise ; the gas then flows through passages in the casing towards the outlet pipe, whioh is furnished with a regulating aorew. The preeaure of the gas is thus balanced against the weight of the bell, and the use of pietons attached to the bell is avoided, as also is the difficulty which would arise in connection with their paoking. (.Accepted Jlarch 28, 1900.)

9196. W. T. Sugg, WestmtDster. Kegulatlng Gaa Pressure iD Incandescent Lighting. [2 P igs.) May 1, 1899.- It is stated th!lot the moat suital>le pre88Ure of gas for use in intensive incandescent gaslightin~ ie about 9 in., and that this pre88ure is most conveniently obtained by means of a water­driven pump or oompreasor, t he speed of which is regulated according to t he number ot lights. For this purpose, the follow­ing means are employed to cut off the water supply when a certain .:as pressure ia exceeded, and to turn it on again when the gas has fallen to the normal pressure. Two vertical gas-tight vessels of equal sectional o.rea, and preferably concentrically arranged, are connected near t heir bottoms, and filled with water to a oerto.in height. Qas from the compressor is admitted to the upper part of the outer Te88el, and when the pressure therein becomes excessive, forces the water into the central veasel, which contains a float connected to a lever which actuates a out·oft valve on the pipe which supplies the water motor, thereby check­ing or arresting the action of the compressor. The outer annular veasel may also contain one or more floats on t he spindles of which are mounted conical valves seated in a diaphragm below the gas inlet; the sinking of these floats in consequence of the excessive gas pressure closes the valves and prevents all risk of

E N G I N E E RI N G. blowing from one vessel to the other. The inner vessel is how- tion gradually ohnnges, so that the outflowing liquid is caused to ever, furnished with a pipe communicating with the ope~ air, move in a direction parnllel to the axis of rotation, this change in

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through which any ga' blown into it may escape. (Accepted Jl arch 28, lQOO.)

GUNS AND EXPLOSIVES. 9341. Sir W. G. Armstrong, Whltwortht and Co.,

Limited, Sir A. Noble, and R. T. Brankston, New· castle. Field-Gun Carriages. [4 Pigs.] May a, 1899.­All the parts of the elevating gear of field-gun carriages are ~ttached to, or carried by an elevating bracket, whioh is dropped mto place on one side of the carriage, and provided with boles whioh fit on to corresponding studs on the carriage, so that the gear is ready for elevating or depressing the gun without the t rouble of fixing it to the carriage. The gun rests on and is ele-

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yate~ by an arm ?r crank attached to a shaft revolving in bear­w~s m the elevatmg bracket, parallel to the trunnions ; and on t.b1s shaft is mounte~ a. worm wheel, adjustably connected to the shaft by means of fnot10n \vashers, and revolved by means of a worm and handwheel. The gun, instead of merely resting on the arm or crankpin, and caused to follow the crank by gravity, may be positively operated by means of a longitudinal slot or groove in the gun, engn~ing the crankpin, so that the gun follows any move­ment impartea to the p in. (.Accepted lJJa'rch 21, 1900.)

9342. Sir W. G. Armstrong, Whitworth, and Co., Limited, A. G. Badcock, and S. M. Murray, New· castle. Breech Mechanism of Guns. [28 F i gs.] May 3, 1899.-This invention relates to breech mechanism for quick­firing guns, espeC'ially those having the De Bange or a similar system of obturation, and its objeot is to allow t he breechblock to be swu.ng clear of the breeoh opening after the breech screw has been unlocked. For this purpose the shaft forming the pivot of the carrier arm of the breechblock, instead of working in fixed bearings, works in a groove or movable bearing, so that it can move rearwards when the carrier arm is swung back. The breech screw and obturator are pivoted to the carrier arm in the ordinary way, and on the carrier arm is a projection having formed on it one or more pins carrying rollers or sliding blocks,

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which run in corresponding grooves cut in t he gun. Other g rooves of suitable form are C?t in the gun to receive t~e shaft of the carrier arm, and to allow 1t to move rearwards dur1ng part of the swinging action. When the mechanism commences to swing, after the gun is unlocked, the projection on .the ?arrier arm bears against the gun and pushes the shaft, whioh 18 key~d on the carrier arm, rearwards along t he second grooves, wh1ch are so formed as to cause the obturator to clear its seat in swinging. In closing the mechanism, the pins on the carrier arm bear on the opposite side of the. ~rst groo\'e~, and thus th.e breech screw can be brought into pos1t10n for lockmg the sorew m to the gun. The first and second set of g rooves may be out in the carrier arm instead of in the gun, the pins working therein being then attached to the l{UD. (.Accepted March 21, 1900.)

HYDRAULIC MACHINERY. 8030. E. E. Marchand, Erment, Upper Egypt.

Centrifu~al Pump. [3 Figs. ] Apd~ 17, 1899.- The.objeot of this invention is to so construct a centr1fugal or a tu~b~ne pump that the liquid shall move along a curved passage, avo1dmg sharp turns or bends, and leave the pump ~n a directi~n at ~ight an~les to its plane of rotation. The turbme has a .smgle mlet ?rtfice communicating with t he suction tube a~d formm~ the ope_mng of a. circular passage of curvellnear seot1on, leadmg to wn~gs or blades which extend into the body of the pump. The casmg of the pump is of conoi~al for~, .and has concentrically moun~ed within it a rotary turbme of Slmil&.r form, on the surface of whtoh are curved ribs or blades which occupy the annular space between it and the casing. These blades a re so curved that the inflowing liquid at first meets them nearly in the direction of the plaJ?e of rotation as, however, t he blades appronoh the out!et then d1rec-

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the direction of flow being gradually effected, and sharp and sudden turns involving loss of energy being avoided. (Accepted 1Jlarch 21. 1900. )

LIFTING AND HAULING APPLIANCES. 4275. s. Gibbs and A. E. Downing, West llromwich.

Sustaining Appa~atus for Pulley Blocks and Lift· tug Tackle. [2 Figs.] February 27, 1899.- The apparatus is stated to be specially applicable to pulleys, hoists, and the like and consists of a casting pivoted at tts :centre, and having at on~ end a curved projection, and 1\t the other a segmental hook. The drawings show two forms of apparatus, in the former of which the hook is adaJ?ted: to sustain a r?P~ or ro~ at right an~les to its own length_, while m the latter 1t IS apphe~ to sustain a rope parallel to tts length. The hook and proJeCtion ate, in the latter

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case, Blotted, and the rope lies within the slots and is furnished with a button by means of which it is sustained. Both forms of apparatus operate substantially in the same manner, the rope, or rather the button, thereon presses on the convex edge of the hook P';JShi~g it aside, and passmg over its point , thereupon engage~ wtth tt. The rope may be released by still further raising it, so ~hat the weight presses on the upper side of the project ion, throw­lOg the hook backward so far that tbe rope or the button tbereon pa9ses below it before sufficient t ime has elapsed to allow of its returning to the orig innl position. (Accepted 1Jfarch 21, 1900.)

MACHINE AND OTHER TOOLS, SHAFTING, &c. 5112. P. Mallet, Paris. France. Gear for Trans·

mttttng Motion. [17 Pigs.] March 8, 1899.- This invention has for object the const ruction of gear for transmitting motion from a drh·ing to a driven shaft, nnd automat ically varying the speed of the latter in inverae ratio to the resistance to which it is subjected. The in\'ention is described by way of example as applied to the propulsion of a motor vehicle, but it is stated t hat it may advantageously be employed in tool machines and other instances in which the driven shaft is subject to a varying resist­ance. According to one arrangement, a pair of rotary discs loosely mounted upon a transverse shaft and pressed together by adjustable springs, are driven by a bevel wheel capable of being clutched on the driving shaft. These discs actuate by friction a roller held between them and fixed upon a longitudinally movable spindle on which is loosely mounted a second roller to main­tain the parallelism of the discs. This spindle is furnished

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with a worm which 1:1;ears with a wormwheel fixed upon the driven shaft. The springs wbioh act upon the rotary disc also transmit to the spindles, through links and bellcrank levers, .a force tending to maintain the actuating ~oller towards th~ peri­pheries of the discs. If, however, the reslBtance to the rolhng of the vehicle is increased, the foroe thereby applied to the worm, in a direction t nngential to the wormwheel, onuses the spindle to move longitudinally, carrying the roller towards the centres of the discs, and reducing the speed of. th_e d:iven shaft, ~bile the mechanical advantage of the oombmat ton 1s oorrespondmgly increased. The apparatus is fitted with a oonion.l friction brake, which nets automatically to oheok excessive speed ; and other and somewhat more complex arrangements for attaining the ohjeot in view are also illustrated and deecribed. (Accepted Jllarcll 21, 1900. )

5985. T. B. Sharp, Birmingham. Rolling Metal Tubes. [14 Figs.] .M~rch .20, 1699.-The obje?t of this _inven­tion is to obviate oer tntn d isadvantages attendmg the ctrcum­ferent ial rolling of metal tubes in an ordinary lathe in the manner referred to in the applicant's prior specification,

(MAY 4, 1900.

No. 18,307,. of ~887, and to . aut.omatio~lly and simultaneously effect oertam adJuStments wh1ch have h1therto been successively effect~d by th~ hand o~ the operator. It is stated that the maohme essent1ally oonslSts of a bed having mounted upon it a. he~dst~ck provided with ~ fast -and-loose pulley, the spindle s>f wh1ch 1s connected by suttable &'Baring to a sorew shaft which operates a saddle carrying a reducing box in which are mounted a number of balls or rollers capable of being closed or tightened upon the t ube operated upon, which is placed on a mandril held!

p cdJ£· 1---~ - . - ~ .. - =--- 3

__ ._ _________________ __.~_...__ in a chuck by maans of a screw or like device. When t.be mandril and tube are fixed in position, the machine is set in motion, and ~he balls closed upon the tube so as to nie and thin it, commenc­mg near the end secured to the mandnl. The saddle carrying the reducing box slowly travels along the bed towards the bead­stock, unt il the belt is thrown from the fast to the loose pulley by means of a regulatable distance-piece fixed to the slide, the machine being thus stopped when the tube is finished. (Accepted Jlarch 21, 1900.)

STEAM ENGINES, BOILERS, EVAPORATORS, &c.

9975. G. G. M. Hardlngham, London. (E. D ol by and A. C. A u den, J eppestottm, J ohalntltesburg, South ~jrica.) Water-Tube Boiler. [4 Pigs. ] May 11, 1899.-Tbe boiler comprises an annular water chamber within which the fi regrate is arranged, and whence a series of straight heating tubes extend up· wards, their upper extremities communioa.ting with a water and steam drum. These tubes are arranged to form a conical combus· t ion chamber, and may comprise several concentric groups be·

tween and around which the heating gases are conducted. The space above the ashpit and fi re doors is not occupied by tubes, but by a feed-water heater, and the entire apparatus is enclosed in a double casing through which air on its wav to the furnaces passes 11nd becomes heated. It is stated that the generator above de­scribed is adapted for use with launches, motor cars, ftre engines, and in other mstances where lightness, accessibility, and quick steaming qualities are desired. (Accepted ill arch 28, 1900.)

VEHICLES. 21,202. W. Maek, Hannover, Germany. Combined

Automatic Fender and Brake for Tramcars. [S Pigs. ] October 24, 1899.-Tbe combined fender and brake is so con­structed that as soon as the car is obstructed, the brake is auto­matically applied, checking the speed of the car, and preventing the obstruct ing person or article from being run over. A pair of arms, P.ivoted to the underside of the platform of the car, carry t he rails which support the fender frame ; these rails are trans­versely connected by a metal rod, whioh carries at either end a

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connecting bar, the obber end of which is pivoted to the brake lever. These levers are mounted on a rod journalled in brackets secured to the underside of the car in front of the wheels, their shorter extremities beiug conneclied by a weighted cross-beam, while their longer extremities carry the brake. When the fender meets with an obstruction, the brake is applied, and remains in action until the obstruction is removed, when the parts ar& ret urned to their original position by the weighted beam. (Ac­cepted Jl arch 28, 1900. )

UNITED STATES PATENTS AND PATENT PRAOTIOB •. Deecript ions with illust rations of inventions patented in the·

United States of America from 1847 to the present time, and, reports of trials of patent law cases in the United States, may b&, consulted, gratis, at the offices of ENOI.NEKRING, 95 and 36, Bedford-­street, Strand.

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