Elementary Lessons in Physics - Forgotten Books

ELEMENTARY LESSONS

IN PHY S I CS.

JOHN B . GIFFORD,

BUa '

rnnm-JNT OF SC HOOLS, PEAB ODY ,MASS.

TEA C H ER’S ED I T I ON .

THOMPSON, BROWN. AND COMPANY,

BOSTON. CHICAGO.

E dwHarvard C ollege Library ,

D00 . 20, 1918 .

Transferred f om

Education Liblary.

Cbpyright, 1894.

B Y JO H N B . e non n .

PREFAC E.

THE following Lessons have been growing into their

present form for several years, during which time they

have been used in classes under the supervision of the

author. With in the past year theyhave been revised,withtheaim ofadapting them to general use.

It is confidently hoped that these Lessonswill meetawant wh ich is being increasingly felt by teachersandschool officers forasuitable text-book toaid them in

training the pupils of the upper grammarand lower h ighschool grades to observe, to th ink ,and to express thought,

and in revealing to them some of the laws inaccordancewith which physical changes occur.

It has been theauthor’saim to guide the investigationsof the learner by directionsand questions so definite thathewill generallybeable to get the points desiredwithoutaid . Occasionallyaquestion isasked wh ich onlyasmallproportion of the class may beable toanswer ; but thequestion should at least secure theattention ofall,andprepare them to grasp the truth when it comes ; and thecloser workerswill get the exercise wh ich they need .

vi PREFACE.

The illustrations have been introduced to showthe con

ditions of the experiments,and not the results.

The Teacher’s Edition contains some further h ints on

preparing apparatus,and statements ofall observations,inferences, other factsand explanations called for in the

Lessons.

Messrs. Frank L. Keith , J. M. Dill,and Charles E. King,

of Boston, Mr. Clarence B oylston, of Milton , Mass ,andMr. Preston Smith

,instructor in Physics, B rockton, Mass ,

have kindly read th rough these Lessons in manuscript or

in proof,and suggested many valuable improvements.

Whatever of merit there maybe in theaimand generalplan of thework should be largelycredited to myesteemed

teacher in Physics, Mr. George H . Martin,of B oston.

JOHN B . G IFFORD .

JUNE, 1894.

C ONTENT S.

Topics marked (1)are suggested for the Earlier study, in schools inwhich thiswork isnot confined toasingle year.Thosemarked are suggested for the later study,where thework Is distributed through

two ormoreyears.

I . NATURE or MATTER

Matter, B ody, Substance, Impenetrability.

II . DIVI S IONS or MATTER

Molecule, Mass, Atom.

III . STATES OF MATTER ?

Liquids, Solids, AeriformMatter.

IV. CHANGES IN MATTER

Chemical Change, Physical Change.

V. FORCE

Definition, Physicaland Chemical, Muscular Force, Gravitation, Gravitgfi Cohesion, Adhesion, Heat, Light,Magnetism, Frictional Electricity, Voltaic Electricity,Correlation of Forces, Molecular Attraction , MolarForce, Momentum, Inertia, Work

,‘ Power,‘ Energy,’

Composition of Forces.

‘

GRAVITYCentre of Gravity,’ Line of Direction,

‘ Equilibrium}Falling B odies,

’ Pendulum,‘ Pressure of Liquids?

Water Works for C itiesand Towns,Spirit Level,

Springsand Wells,1' Artesian Wells, FloatingandSinking, Specific Gravity} Pressure of Air, Barometer,

viii CONTENTS.

VI I . SIMPLE MACH INES ‘

Lever, Wheeland Axle, Pulley, Inclined Plane, Screw,Wedge.

VI II HEAT

Sources of Heat, Ef eats of Transfer of Heat,Latent Heat!

MAGNETISM

Magnets, TerrestrialMagnetism.

X. FRICTIONAL OR STAT IC ELECTRICITY ‘

HowExcited , Electroscopes, Kinds of Electricity,Conduction

,I nduction.

VOLTAIC ELECTRIC ITYVoltaic Element, HowProduced , Efleets.

XII . SOUNDHowProduced, Transmission of Vibrations, VibratingS trings, Vibrating Columns of Air.

‘

XI II . IAIGHT e o o o o 0

Sources, Porte Lumiere, D irect Transmission ,1' Shadows,1'Reflectionfl

“ Refraction,! M icroscopes,’Refracting Telescope,

‘ Solar SpectrumCHEM I STRY OF AIR AND WATER '

Composition of theAir, Properties of Oxygen, Combustion,Composition of Water, Changes m the Human B ody.

SUGGESTIONS TO TEACHERS .

PUPI LS may performat home such of the experimentsasdo not call for specialapparatus. Each teacher must decidefor h imselfwhether th is plan is the most satisfactory for h isclass.

Wherever the experimentsare performed, each pupil shouldobserveand inferfor h imself,and commit towriting the results

of h iswork before theyare reported in the class exercises.

These records may be made upon separate sheets of paperof uniform Size, each statement marked to correspondwith thedirections in the manual. I f only one observation is called forunderan experiment, it ismarked Obs. ifmore than one

,theyare numbered Obs. 1, Obs. 2, etc. In the sameway inferencesare marked

,— Inf.,

or I nf. 1, Inf. 2, etc. Other facts to berecorded under each experimentare usually numbered.

After these results have been reportedand compared in therecitation

,and opportunity given for correcting errors,by te

peating experiments, it would seem well that they should be

neatly recorded in note-books.

Th ismaterial Should form the basis of muchwritten languagework , inwh ich the pupil should develop the subjectassignedby complete descrip tions of exp eriments, with drawings of the

apparatus used .

For the derivation of terms, suggestedas profitable languagestudy,alist of the required prefixesand suffixes, with their

meanings,will be found on page 157.

Thework laid out in these Lessons mayall be donewithaclass inaSingle year ; but somewill prefer to distribute it overalonger period,and the derivation of termsand manyof the

general topics may be omitted without hindering the studyof

the others.

ELEMENTARY LESSONS IN PHYSICS.

I . NATURE OF MATTER.

MATTER, IMPENETRAB ILITY.

OB SERVATION, DERIVATION, INFERENCE.

EXPERIMENT 1 . (To be performedat h ome.)

FILLabottle W ith water,and insert your pencil.Observation . Statewhat thewater does.

(In NOTE Experiment 1 . Obs. yam a/% waferInference. What causes it to do this?(NOTE-Boox . ) 1a1 . $4 %M was a/ ecu/ex,

area/M was no room%S éé Mae/ C% zaferiwater mm come out .

1 . Howdid you learnwhat thewater did ?(NOTE-BOOK . ) 1 . d emo e?am am .

Callafact learned through the sensesan obser

vation.

See preface for suggestions in regard to records in Note-book .

2 ELEMENTARY LESSONS IN PHYSICS .

In the dictionary you will find observe givenas formed from the

Latin observare, meaning to payattention to, to watch. After this is

placed the suffix tion , meaning theact of.

I nf. 2. What is the meaning of thewholewordas you get it fromits formation ?(NOTE -BOOK . ) I nf. 2. g m éé 7

4£4

fiat/4 . c? more” mean fé acea/fld

fe

ym ath (0,

2. Can you seeanyconnection between th is meaningand the senseinwhich we have used itabove(NOTE-BOOK . ) 2. £ 4 fi t 44 7mm, w 44 em f

3/

This tracing out the origin ofwords is called derivation .

In thisworkalways tryto discover the connection between the original meaning of the wordand the sense inwhich you find it used .

3 . Howdid you learn what caused the water to

run over in theabove experiment ?

(NOTE-BOOK .) 3 . d éaerzea/ e? {y é/M

Callafact obtained by thinking, or reasoning fromother facts,an inference.

Give the derivation of th isword .

(NOTE -BOOK .) d e

p

t/W ee ck%em ea/%om % m

we exec, W M/

(afiery%ewaea{ M M em s,

m ean/77

dé ’

gate/52}

{lbac! ma, dome/m o {é

eeaafi as {fat wécg % te 04 deride deemed {0 lb

{ft/J t‘

cZ !afi er

y/z!%Zwaea/ 4? éémé

fl

ere}.

NATURE OF MATTER. 3

EXPERIMENT 8. (At h ome.)

Holdingan inverted tumbler evenlyaboveabasinofwater, push it downward into thewater.

Obs. Observe the height of the water under the

tumbler.

Inf. 1 . What keeps it from rising higher ?

Inf. 2. Why does that prevent it from rising ?

1 . Name three other things that take up room .

2. Doesathought take up room

3 . Can you think of other thingswhich do not

Call thatwhich occupies room matter.

BODY .

4 . Name six differentp ieces ofmatter.

Call them bodies.

5. What, then, isabody

4 ELEMENTARY LESSONS IN PHYSICS.

SUB STANCE.

6 . Name six different kinds of matter.

Call each kind ofmatterasubstance.

7. What isasubstanceDerive substance.

I nf. 3 . Howmany bodies can occupy the samespaceat the same timeCall the property ofmatter bywhich no two bodies

can occupythe same spaceat the same time impenetraDefine impenetrability.

Derive the term .

Describe experiments showing the impenetrabilityofmatter.

DIVISIONS OF MATTER. 5

I I. DIVI SIONS OF MATTER.

MOLECULE, MASS .

EXPERIMENT 3 . (At h ome.)

Breakalump of salt into several pieces.

Dry one small piece thoroughly,and powderas fineas possible inamortar.

Notice the size of these particles.

Imagine the division to be continued until the

smallest particleswhich can exist by themselves havebeen formed .

Call thesemolecules.

Thus, the smallest particles ofany substancewhichcan exist by themselvesare called molecules.

Derive molecule.

Callanyquantityofmatter greater thanamoleculeamass.

Derivemass.

1. Name six masses ofmatter.

COMPOUND .

Each of these molecules of salt is composed of the

metal sodiumandagreen gas called chlorine.

Let the teacher Showapiece of sodium,and preparealittle chlo

rine byadding sulphuricacid toalittle bleaching powder inatesttube or large-mouthed bottle.

Be careful not to inhale much of the chlorine. Sodium Should be

handled with forceps or dry paper,and kept under petroleum or

kerosene.


Obs. Describe sodiumand chlorine.

Sodiumand chlorinearealways combined in exactlythe sameproportion to form salt.

Callasubstancewh ich,like salt, has been found to

be composed of two or more different kinds of mattercombined in definite proportionsacompound .

Water,alcohol, acids, kerosene,and iron-rustarecompounds.

2. Compoundsarewhat kind of substances ?Derive the term.

ELEMENT.

Sodium has never been separated into different

kinds of matter. Neither has chlorine.

Call such substances elements.

3 . What do you understand by such substancesOxygen , hydrogen, nitrogen, carbon, iron ,

lead, tin,

gold,and silverare some of the common elements.

Derive element.

ATOMS .

4 . A molecule of salt containswhat elements?I nf. Howmust the quantity of sodium inamole

cule comparewith the quantity of salt in the mole

cule

Call the smallest particle of matterwhich can exist

combinedwith other particlesanatom.

5. What isanatom ?Derive the term.

DIVISIONS OF MATTER.

6 . Name the divisions of matter wh ich we haveconsidered.

7. Which of these have you seen ?

2. Do the others really exist ?

SIZE OF MOLECULES .

EXPERIMENT 4 . (At h om e .)

Addadrop of bluing toatumbler ofwater.

Obs. State the effect.

1 . What gives the color to the bluing

2. What to thewater in the tumbler ?3 . Whereare these particles ?4 . What do you infer in regard to the Size of

the molecules of coloring matter?The odor ofasubstance is supposed to be due to

small particles of the substance floating in theairandcoming in contact W ith the nerve of smell. A little

sachet powder W ill fill theairwith perfume foralongtimewithout undergoingany sensible loss ofweight.

Inf. 5 . What do you infer from th is in regard tothe Size of the molecules ?


III . STATES OF MATTER.

1 . LI!UIDS.

EXPERIMENT 5 . (At h ome. )

Put your finger intowater,and stir it round .

Obs. 1 . Observe the ease with which the fingerismoved through thewater.

Inf. 1 . Makean inference in regard to the movement of the particlesofwateramong themselves.

Remove your finger, keeping the end downward .

Obs. 2. Observewhat formsat the end .

Inf. 2. Inferwhether the particles tend to separateor to cling together.

1 . What two things do you find to be true of the

particles ofwater ?2. Name three other substances ofwh ich the same

is true.

3 . What common name may you give to these

substances4 . What would you say that liquidsare ? (See

question 1,above. )Derive liquid.

2. SOLIDS.

5. Comparewood, iron,and glasswith liquids.

In which of theabove points do theyagree ?(See question

Inwhich do theydiffer

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3 . AERIFORM MATTER.

EXPERIMENT 7 . (At sch ool.)

Fit two horse-radish bottles with air-tight cork

stoppers.

Half fill one bottlewith water.

Cut off two pieces of glass tubingan inch longerthan the height of the bottles,and one pieceabouttwo inches long .

To cut glass tubing makeanotch on one Side bytwo or three for

ward strokes ofatriangular file, grasp the tube in both handswith thethumbsagainst it Opposite, on the other Side from the notch ,andbreak bypressing outwith the thumbsand drawing towards youwiththe outsides of the hands. Heat the ends of the pieces of tubing in thegas oralcoholflame until the sharp edgesare rounded .

Witharat-tail file boreahole in the stepper of the

bottle containing thewater, just large enough for the

tube to fitair- tight ;and push one of the longer tubes

through the hole so that it will reach nearly to thebottom of the bottle.

STATES OF MATTER. 11

In the same way fit the other two tubes into thestopper of the other bottle, letting them projectaboutaquarter ofan inch belowthe stopper.

Connect the two bottles byapiece of rubber tubing

drawn over the ends of the glass tubes which projectbut littleabove the stoppers.

Obs. 1 . What is in the bottles now?Taking the end of the projecting tube in themouth ,drawout as muchairasyou can .

Obs. 2. What is the effect

Inf. 1 . Infer the cause of this.

I nf. 2. What tendency of the molecules ofair isshown in this experiment1 . Howdoesair differ from liquids

2. Inwhat respect is it like liquidsCall such matterasairaeriform matter.

3 . Whatare its distinguishing properties ? (See

questions 1and


4 . Defineaeriform matter.

Deriveaeriform.

5 . What otheraeriform matter have you seen

6 . What name isapplied to both liquids,andaeriform matter ?

GAS AND VAPOR.

EXPERIM ENT 8. (At sch ool. )

Boilalittlewater inatest tube.

Obs. Noticewhat is formed,andwhere it goes.

I . What is it formed from

STATES OF MATTER. 13

Inf. 2. When wet clothing dries where does thewater go ?1 . Can you see thiswater in theair2. In what state of matter iswater ordinarily3 . In what state of matter is this invisible water

in theair ?Call suchaeriform matter vapor.

4 . Howdoes it differ fromair'

? (See questionCall suchaeriform matterasair gas.

5 . What other gases have you knownWriteaconnected description of the different states

ofmatter, Showing by illustrationswhat each is.


IV. CHANGES IN MATTER.

1 . CHEMICAL CHANGE.

EXPERIMENTa. (At sch ool.)

Placealittle copper inatest tube.

Addabout twice itsweight of nitricacid .

Obs. Observe,and state the effect in the liquid,andabove the liquid .

I nf. 1 . Inferwhat gives the color to the liquid .

Would copper give it that color Would nitricacidI nf. 2. Howmanynewsubstancesare being formed

in the liquid

1 . Howdoes each differ from copper ?

2. Howdoes each differ from nitricacidInf. 3 . Whatare they formed from ?

Why do you th ink so

I nf. 4 . Are the molecules of these newsubstancesthe sameas those of the copperand nitricacid3 . Why do you think so ?

I nf. 5. Are’

theatoms the sameCallachange in which theatoms of one or more

substances combine in suchawayas to form one or

more newsubstancesachemical change.

Derive the term chemical.I nf. 6 . In the preceding experimentwere the cop

perand nitricacid changed into nothing ?

Inf. 7. What became of them ?

4 . What other chemical changes have you seen

CHANGES IN MATTER. 15

2. PHYSICAL CHANGE.

Wereany newsubstances formed in the

experiment

Howdoes the ninth differ from this

Callachange in matter in which no newstance is formedaphysical change.

What kinds of changes have occurred in

of the other experiments performed

PHYSICS .

Call the knowledge of physical changesPhysics.

Derive the termsphysicsand physical.Call the knowledge of chemical changesWriteaconnected description of the changes in

matter, illustrating by experiments.


V. FORCE.

1. DEFINITION.

Call that which produces, or tends to produce,

change force.

As towhat this cause of change reallyis,we knownothing. We

must infer that there isacause,andwe name it force.

Derive thewordforce.

2. PHYSICAL AND CHEMICAL.

Inf. l. The cause ofaphysical change wouldcalledwhat kind ofaforceInf. 2. The cause Ofachemical change would

calledwhat kind ofaforce ?It isalso called chemicalafi nity.

Deriveafi nity.

1. Itacts between what divisions ofmatter ?2. Physical forcesact between what divisions

matter ?3 . DIFFERENT FORCES.

a. MUSCULAR FORCE.


Liftachair,and hold itatarm’s length .

I nf. 1 . What produces this change1 . Bywhatwas the force exerted

Inf. 2. Inferaname for force so exerted .

2. Give other illustrations of the use of such



4 . In the last two experiments gravitationactedbetween what two bodies

5. Between the earthand what other bodies haveyoufound that this forceacts

Call theattraction between the earthand bodies on

or near its surface gravityDerive the term .

6 . What other nameapplies to th is force ? (Seequestion

7. Which is the more definite name WhyInf. 2. Inferanother name foraforcewh ich draws

together.

Since it draws masses together it is called molarDerive thesewords.

Obs. 2. If you fastenastring toahorse-chestnut

and Swing it so that it moves in the circumference of

acircle,what is the effect upon the fingers

Obs. 3 . Ifyou let go the string,what happensInf. 3 . This shows that abody moving in the

circumference ofacircle tends to move in what kindofaline8. What other evidence of this tendency have you

noticed

This tendencyhas been called centrifugalforce.

9. Describe the tendency.

Derive centrifugal.

FORCE. 19

The earthand other planets move round the sun in

nearly circular orbits.

I nf. 4 . What prevents them from moving off in

straigh t linesc. COHESION.

I nf. 5 . Whatwould you call thatwhich holds themolecules ofasubstance together (See Inf.10. This forceacts between molecules of the same

kind, or of different kindsCall the forcewhichtogether cohesion .

Derive theword .

d . ADHESION.

EXPERIM ENT 1 4 . (At h ome. )

Insert your pencil in water,andwithdrawObs. Observe the effect upon the pencil.

I nf. Infer the cause.

EXPERIM ENT 1 5 . (At h ome. )

Rub the lead of your pencilacrossapiece of paper.

Obs. Observe the effect upon the paper.

I nf. Inferwhat causes th is.

1 . Are the molecules of leadand paperalikeCall the forcewh ich holdsmolecules of different

substances togetheradhesion .

Deriveadhesion.

2. Howdoes it differ from cohesion

3 . In what do cohesionandadhesionagreeHence the term molecularattraction isappliedto both .


e. HEAT.

EXPERIMENT I s. (At h ome.)

Holdapiece ofwax near the flame ofaburningmatch .

Obs. Observe the effect upon thewax.

Call the forcewhich causes this change heat.f. LIGHT.

EXPERIMENT 1 7 . (At sch ool.)

Moisten astrip of paper four '

inches long in asolution of silver nitrate.

Shut one half of the paper between the leaves ofabook,and leave the other half exposed.

Fig . 6 .

Place the book where the sun will shine upon the

exposed half of the paper,and leave it there for tenminutes.

Obs. Observe the effect upon each half of the paper.

I nf. Inferwhat force produced the change.

FORCE. 21

g. MAGNETISM.

ExPER IMENT 18. (At sch ool.)

Obs. Bringamagnet near to, or in contact with ,pieces of copper, iron , zinc, lead, silver

, steel, wood,and other substances,and observe the effect.

I nf. Inferwhat must have produced this effect.Call this force magnetism.

Derivemagnetand magnetism.

h. FRICTIONAL ELECTRICITY.


Foldapiece of silk cloth intoapad five or six

inches square.

Warm the pad,andalsoastraight lamp chimneyor stick of sealing wax .

Obs. 1 . Bring them successively near some smallbits of paper,and see if theyaffect the paper.

Rub the ch imney brisklywith the silk,and repeatthe experiment.

Obs. 2. State the effect.

Inf. 1 . Infer the cause.

I nf. 2. Infer howthis forcewas produced .

Call itfrictional electricity.

Derive thesewords.

i. VOLTAIC ELECTRICITY .

EXPERIMENT 20. (At sch ool.)

Intoatumbler two thirds full ofwater pouraboutone twelfthasmuch sulphuricacid.


Addasmuch potassium bichromateaswill dissolve.

In this solution insertaplate of Sheet copperandone of Sheet zinc, eachabout 2 x 5 inches.

Obs. 1 . Holding them so that theywill not toucheach other, observe the surfaces of the metals.

Obs. 2. Touch their outer ends together,and oh

serveanyaction upon the surface of either or both .

I nf. 1. What kind of change is this ?Remove the plates, punchahole near the top of

each ,and connect them byapiece of copperwire 16inches long,as shown in Figure 7.

Obs. 3 . Insert the plates in the solution ,and see if

there isanyaction upon the surface of either.

Remove the plates.

Magnetizealarge needle or halfaknitting needle,

by rubbing the end ofamagnet from one end of the

needle to the other,always in the same direction .

FORCE. 23

Suspend this needle byasilk thread so that itwillbalance inahorizontal position .

When the needle has come to rest hold the wireconnecting the plates parallel with the needleandjust belowit ;and then justabove it.

Obs. 4 . Was the needleaffected ?Insert the plates in the liquid in the tumbler,and

hold thewire to the needleas before.

Obs. 5. State the effect.

Call the force which produces this change voltaic


Inf. 2. Howwas it developed ? (See Inf. I . )Derive the term voltaic.

1. Name the different forceswhich we have beenconsidering .

2. Which of theseact upon massesI nf. 3 . What kind of forcesmayyou call them3 . Whichact upon molecules ?I nf. 4 . What kind of forcesmay theybe called ?4 . Wh ich tend to bring bodies together ?

Gravitation hasalso been called molarattraction .

5. Which of these forces hold molecules together ?

6 . What common name have you given to these

forces

Writeaconnected description of the different forces

studied, illustrating them by experimen ts.

4 . CORRELATION OF FORCES.


Touchacent to your check .

Rub one side of it brisklyagainst your Sleeve forafewseconds,and touch it to the checkagain .

Obs. Observeany change.

I nf. Infer howitwas produced .

1 . What forcewasapplied in the experiment ?

2. What forcewas developed by it3 . Inwhat other cases have you noticed that heatwas developed by friction ?



Inf. 7. In the use ofalocomotive to moveatrainof carswhat forceacts first in the fire-box ?Inf. 8. What force is produced by thisaction ?I nf. 9. What effect does the heat in thewater of

the boiler have upon the train of cars ?Callaforceapplied throughamachineamechani

cal force.

Derive the term.

3 . The heat produced in the fire is here converted

intowhat kind of force

4 . Lightning is theaction ofwhat force ?5. When it strikesabuildingwhat effect is often

produced

Inf. 10. Inferwhat force must have been developedin order to produce this effect.

6 . What changes of force occur hereInf. 11 . In producing electric light for townswhat

forcesact,and in what order ?Call this relation of forces bywhich one force may

be converted intoanother correlation of forces.

Derive correlation .

Explain from illustrations, in writing, what is

meant by correlation of forces.

5. MOLECULAR ATTRACTION.

I . What two forms of molecularattraction havewe considered ?

Define each .

FORCE. 27

SOLUTION AND CRYSTALLIZATION.

EXPERIMENT 23 . (At sch ool. )

In two thirds ofatumbler of boiling water dissolveas much (powdered)alumasyou can .

Suspend asmall string over the middle of the

tumbler, so that itwill reach nearly to the bottom of

the liquid .

Place the tumblerwhere it will not be disturbed,andallowthe liquid to cool Slowly.

Obs. Observe what forms upon the string, andupon the inside of the tumbler.

Potassium bichromate, copper sulphate, or iron sulphate may beused in place of thealum.

1 . What state ofmatterwas thealum ?2. What state ofmatterwas thewater ?3 . What state of matter did thealum become in

the hot water ?Call suchamingling ofasolid withaliquid 3

solution .

The term solution isalsoapplied toa‘mixture ofagaswithaliquid, or toamixture of two liquids.

Derive the term solution.

Inf. 1 . What force must haveacted to hold the

molecules ofalumandwater together ?I nf. 2. What force must have been overcome in

forming this solution ?

4 . What forcewasapplied toaid the solution

5. When this force disappearedwhat happened ?


Inf. 3 . What force must haveacted to bring themolecules ofalum togetheragain ?Inf. 4 . In this experiment does heatactwith co

hesion, or in opposition to it ?

6 . What kind of faces did the solids formed from

this solution have ?Call solids having such facesand formed in this

way crystals.

Define crystals.

Derive the term .

Call the process of forming them crystallization .

Derive crystallization .

CAPILLARY ATTRACTION.


Inapan or plate containingalittlewater place twoglass plates vertically, So that,with two of their ver

tical edges in contact, theywill formasmallangle.

Obs. 1 . Increaseand diminish the Size of theangle,and observe the height of thewater between theplates.

I nf. l . Infer the cause.

Obs. 2. Oil the plates,and repeat the experiment.

Inf. 2. Observeand inferas directed .


Insert small glass tubes of different sizes inwater,in mercury,and in other liquids.

Obs. Observe the height of each liquid in the

tubes.

FORCE. 29

Inf Infer the cause of the difference observed .

1. Theattraction manifest in Experiments 24and25 is between molecules of what states of

matter2. What is its effect upon the liquid ?Call this form ofadhesion cap illaryattraction.

Describe it.Derive capillary.

ABSORPTION OF GASES.


Obs. 1 . Observe the odor of diluteammoniawater.

The odor is due toammoniagas,which is mixedwith thewaterand is gradually escaping from it.Pouralittle of this liquid intoatest tubeandadd

halfasmuch powdered charcoal.FILTER.

Foldacircular piece of filter paper (three or four

inches in diameter) upon its diameter,and fold itagainupon the radiusat rightangles to this diameter.

Open itat the circumference soas to makeahollowcone,and insert theapex in the mouth ofahorseradish bottle.

Pour the contents of the test tube into the papercone.

Obs. 2. Observewhat happens.

Call thisapparatusafilter.

Call the liquid that passes through the paperafiltrate.


Obs. 3 . Observe the odor of the filtrateand that ofthe charcoal.I nf. 1 . Infer the cause of the change.

The experiment may be repeated using hydrogen

disulphide in place ofammonia.I nf. 2. What does the charcoal do in these ex

periments

I nf. 3 . What forceacts hereFrom this peculiarity charcoal is used asade

odorizer.

Derive th is term .

I nf. 4 . Infer whyadrop of oil on paper spreadsover the paper.

1 . Where does the oil ofalamp burnI nf. 5. Infer howit gets there.

6 . MOLAR FORCE.

a. IMPULSIVE AND CONSTANT.

1 . Howdoes the forcewith whichabat strikesaball compare in the length of time which itactswith the force which draws the ball tothe ground

Callaforce wh ichacts only foran instantanimpulsiveforce.

Define.

Derive the term .

Callaforce wh ichacts continuouslyaconstantDefine.

Derive constant.

FORCE. 3 1

2. What kind of force is the pressure of steam inaboiler

3 . Theattraction of two bodies for each other ?

4 . Forceapplied bya‘blow?b. TENDENCY OF FORCE.


Obs. Tossaball gently upward,and observe carefullyany change in the motion .

Inf. 1 . What produced the motion ?I nf. 2. What caused the changes in it ?1 . Does molar forcealways produce motion or

change ofmotion

2. Givean instance in which muscular force doesnot produce either.

3 . Givean instance in which gravity does not

produce either.

Inf. 3 . What is the tendencyofmolar forcec. VELOCITY OF MOTION.

1 . Howfast doesatrain of cars go2. Howfast doesamanwalk ?Inf. 1 . Call the rate ofmotion ofabody itsDerive the term .

We say thatahorse goes eight milesan hour.

3 . What isan hour ?4 . What is eight miles5. What didwe state in giving the velocity of

train of cars ?

3 2 ELEMENTARY LESSONS IN PHYSICS.

UNIFORM , VARIABLE, ACCELERATED, RETARDED .

6 . Howdo the distanceswhich the earth turns in

successive‘

hours compare

Call sucharate ofmotlon uniform velocity.

7. What is uniform velocityDerive uniform.

8. Whenatrain of cars is getting underway, orwhen it is just coming toastop, howdo thedistances passed in successive seconds com

pare?Callarate of motionat whichabody passes

overadifferent distance in each successive

unit of time variable velocity.

9. Define variable velocity.

Derive variable.

10. Defineaccelerated velocity.

Derive the term.

Define retarded velocity.

Derive retarded .

12. Give examples of uniform velocity.

13 . Give examples ofaccelerated velocity.

14 . Give examples of retarded velocity.

Inf. 2. What kind of velocity is produced byanimpulsive forceactingaloneInf. 3 . Byaconstant forceactingalone ?Inf. 4 . Byan impulsiveandaconstant forceacting

together in Opposite directions?

Think ofabodythrown upward .



Call the inability ofamoving body to change itsmotion inertiaof motion .

Define.

The term inertiaisalso used in the sense of the‘

tendency ofabodyat rest to remainat rest, or ofabody in motion to continue the motion .

Derive inertia.I nf. 2. Call the inabilityofabodyat rest to move

inertiaofDefine.

A man stood on the bowofaboatwhen it struckahidden rock.

Inf. 3 . Inferwhat happened,andwhy.

I nf. 4 . Why is it dangerous to step fromamovingcarriage or car ?Inf. 5. Howmay it be done most safelyInf. 6 . An electric car started suddenly,and many

of the standing passengerswereI nf. 7. WhyI nf. 8. Whydoesatrain of cars start slowlyandacquire speed graduallyI nf . 9. Why can it not be stopped suddenly

I . What is the effect when two rapidly movingtrains meet upon the same track ? Why?

2. In drivinganailwithahammer what is the

forceas it isapplied to the nailInf. 10. Howis the dust removed fromacarpet

by beating ?

FORCE. 3 5

f. RESISTANCE.

OF THE AIR.

EXPERIMENT 3 0. (At h ome.)

Moveafan edgewise quickly through theair.

Obs. Move itat the same rate in the usualway,and observeany difference in the force required .

I nf. I . Inferwhat causes this difference.

Call thatwhich h indersmotion resistance.

Define.

Derive resistance.

Call the resistance in this experiment resistance oftheair.

I nf. 2. It is reallydue towhat propertyof theair ?OF INERTIA .

Inf. 3 . Towhat is the greater part of the resist

ance in startingatrain of cars dueCall it resistance of inertia.Inf. 4 . What does theamount of this resistance

depend upon

OF FRICTION.


Tie one end ofastringaroundabook.

Obs. Holding the other end in the fingers, drawthe book by the string slowlyand with uniform

motion over the carpet,and noticewhetherany forceis requiredafter inertiahas been overcome.

Inf. Inferwhythis force is required.

Call this resistance the resistance offriction.


OF MUSCULAR FORCE .


Obs. Repeat Experiment 3 1 , pressing with the fingers of the other hand slightlyagainst the forwardend of the book,and observeany difference in the

force required to move the book.

Inf. Inferwhat this difference is due to.

OF GRAVI TY .

EXPERIMENT 3 3 . (At h ome.)

Raise the book verticallyby the string .

Inf. 1 . What is the resistance chiefly due to ?Inf. 2. If the book weighs two poundsand you

lift with aforce of three pounds, what becomes of

the surplus forcewhich gravitydoes not resistInf. 3 . Howmuch of this surpluswill be used up

in thatway?q . 4 . How, then , does the sum ofall the dif

ferent forms of resistance compare with the force

resisted ?

I nf. 5. Howdoes the direction of the resistancecomparewith that of the moving force ?Newton has expressed these facts by saying thatactionand reaction are equaland in Opposite direc

tions.

Inf. 6 . What can he mean byactionand reaction

FORCE. 87

g . MEASURE OF FORCE.

EXPERIMENT 3 4 . (At sch ool. )

Makeaspring ofNo . 22 brass wire bywinding itcloselyuponapencil.Cut the string used in Experiment 3 1 between the

bookand the end held in the fingers,and fasten theends thusmade to the ends of the spring .

Fig . 9.

Obs. 1 . Repeat Experiment 3 1,andascertain byarule howmuch the spring is stretched.

Obs. 2. Drawthe book over the smooth surface of

atable,and see howmuch the spring is stretched .

Inf. 1 . Compare carefully the forces used in the

two parts of this experiment.

1 . What is the unit used in themeasure of gravity?Other molar forcesare measured by the same unit.


Makeaone-

pound,atwo-

pound,andafive-

pound

weight, byweigh ing out the right quantities of pebblesin tin cans.

Lift theseweights successively,and note the force

required in each case.

1 . Compareaforce that will sustain one pound

with one wh ich will support two pounds ;

with one which will support five pounds.


h . WORK.

Inf. 1 . What forms of resistance must be overcomein drawingadouble-runner up hill

Call the overcoming of resistance of any kindwork .

Inf. 2. a. Howdoes the work of raisingapoundone foot compare with the work of raising it fourfeet ?

b. With that of raising it ten feet ?c. With that of raising two pounds two feet ?d . With that of raising three pounds ten feet ?1 . What two things must be considered in meas

uring work ?2. What is the unit ofwork with which we have

compared thework in each of these cases?Call this unitafoot-pound .

Define.

3 . Howmanyfoot-pounds ofwork in each of theabove cases ?i. POWER.

Inf. 1 . Which can do more work inan hour,ahorse oralocomotive ?The rateatwhichanagent can dowork is spoken

ofas its power.

Define.

Inf . 2. In measuring power what must we con

sider besides units ofwork done?

FORCE. 39

One foot-pound of work inasecond isaunit of

power.

In measuring the power ofagents capable of doingalargeamount ofwork 550 foot-

pounds of work inasecond is takenas the standard . This is calledahorse-power.

Define.

An engine of one horse-

power is capable ofactingthrough one foot inasecondagainstaresistance of

550pounds, or ofacting through 550feet inasecondagainstaresistance of one pound.

1 . Howfar can it raise 275 pounds inasecond2. Howfar can it raise 1 100pounds inasecond3 . Howfar can it raise 1100 pounds in ten

seconds

4 . Howmany pounds can atwenty horse-

powerengine raise ten feet inasecond

j. ENERGY.

Inf. Think howit is thatamoving body,abent or

coiled spring, oraliftedweight can do Work .

Call theability to dowork energy.

Define.

Derive the term .

It . COMPOSITION OF FORCES .

Fromastrip of sheet lead, out three piecesan inch

square, two pieces 1 X 2 inches, two pieces 1 x 3


inches, two pieces 1 x 4 inches,and two pieces 1 x 6inches ; and makeahole withanawl through one

corner of each piece.

Makeawooden frame two feet longand sixteen

inches high ,andattach two small pulleys to the topof the frameafootapart,as shown in Figure 10.

Fig . 10.

Equilibrium.


Passashort string over one of the pulleysand abook made ofa-bent pin to each end of it.

Hangastrong envelope upon one book,and upon

the other hangan inch leadandatwo- inch lead .

Pour into the envelopeas much sandas the twoleadswill balance.

Whenall the forcesacting uponabody balanceeach other

,it is said to be in equilibrium.

Derive the term.



Hangan envelope on the book with the lighter

weight,and pour into it sand enough to produce

equilibrium.

Obs. Remove the two lead weights,and find their

resultant,andapply it.

1 . This is the resultant ofwhat ?2. It equalswhat ?actswhere ? in what line ?A boat sails through thewaterat the rate of eight

milesan houragainstacurrent of three milesanhour.

I nf. 1 . What is itsactual rate of progress ?

A steamer propelled byaforce thatwould carryherten milesan hour is held back byawind that,actingalone,would carry herasternat the rate of four miles

an hour.

I nf . 2. Howlong will it take her to go twentyeight miles

Two Parallel Forces.

IN SAME DIRECTION.

EXPERIMENT 3 8. (At sch ool. )

On the same side ofalight wooden bar th irteen

inches long place two small screw-eyes twelve inchesapart.

On the opposide side of the bar insert three morescrew-eyesat intervals of three inches from the first

and from each other.

Pass cords from the end screw-eyes over the pulleys,

in the frame used in Experiment 3 6,and balance

FORCE. 43

Fig 11 .

the bar inahorlzontal position by smallweights on

the cords.

Obs. On one of these cords hangatwo- inch lead,and on the otherasix-inch lead ; and find whatweight they will balance, and where it must be

placed to keep the bar horizontal.Inf. 1 . From this infer what the resultant must

be.

A force of 100 poundsandaforce of 200 poundsact in parallel lines in the same direction.

Inf. 2. Their resultant isaforce of poundsacting in the direction, inaline asfar from the line of the greater forceas from that of

the smaller.

Two Forcesatan Angle.

A boat is rowedacrossariverat the rate of six

feetasecond,and carried down stream by the current

at the rate of three feetasecond .

1 . Drawaline on paper, starting fromagivenpointa, to represent the direction in wh ichthe boat would have movedand the distancewhich the rowing would have carried it inthree secondswithoutany current,and markthe end 6.


Drawanother line, starting from the same point,to Showin what directionand howfar thecurrent would have carried it without the

rowing,and mark the end c.

Consider the rowingand the currentasactingat the same time.

Howfaracross the riverand how far downthe riverwill it have been carried in twentyseconds

Mark itsactualpositionat the end of that time d.

Drawaline showing theactual path in whichthe boat has moved.

Connect dwith band c by straight lines.

2. What figure have you drawn3 . What does the diagonal represent4 . What do the sidesabandac represent ?I nf. Infer howthe resultant compareswith the sum

of the components,and with the difference of the

components.

5. Howdoes its direction compare with the direc

tions of the components ?

GRAVITY. 45

1 . Recall definitionand derivation of

2. CENTRE OF GRAVITY .


Suspendaweight fromafixed pointabout twelve inches long, with asmallthread just belowthe point of support.

Fig. 12.

Stickapin throughapiece of card-board near one

edge,and hang it in the loop so that the thread willbe in front of the card-board .


Mark upon the card-board the position of the threadbelowthe loop.

Stick the pin through some other part of the cardboard near the edge, hang it in the loop,and markas before.

Place the intersection of these marks on the point ofapin ,and see if itwill balance in different positions.

If not, repeat the experiment, taking care to markthe positions of the thread exactly.

Call the pointatwhichabodymay be supported inanyposition its centre of gravity.

Define.

3 . LINE OF DIRECTION.

Call the line passing through the centre of gravityofabodyand the centre of the earth the line qf direction of the body.

Define.

4 . E!UILIBRIUM .

a. OF A BODY SUPPORTED AT ONE POINT.

EXPERIMENT 40. (At h omo. )

Stickapin through the card used in Experiment3 9,at its centre of gravity,and pin itagainstavertical surface so that itwill turn easily on the pin .

Obs. 1 . Inwhat positions is it in equilibrium

Obs. 2. In the sameway support the cardan inchfrom the centre of gravity,and find in what positionsit is in equilibrium .

GRAVITY . 47

STABLE EQUI LIBRIUM .

Obs. 3 . Inwhat direction from the centre ofgravityis the supportwhen the greatest force is required to

overturn the body

I nf. 1 . Why ismore force required to disturb the

equilibriumwith the body in this positionA body so supported is said to be in stable equi

librium.

Derive stable.

UNSTABLE EQUI LIBRIUM .

Obs. 4 . Inwhat direction from the centre of gravityis the supportappliedwhen least force is required to

overturn the body

Inf. 2. Why is less force requiredwith the supportapplied there

A body so supported is said to be in unstableequilibrium.

Derive unstable.

NEUTRAL EQUILIBRIUM .

Obs. 5. Where is the supportapplied when the

body is balanced inanypositionA body so supported is said to be in neutral equi

librium.

Derive neutral.b. OF A BODY RESTING ON ITS BASE.

1 . In what position isabook in most stableequilibium

Inf. 1 . Inwhat position of the book will the centre

of gravity have to be raised most to overturn it ?


Inf. 2. In what position of the book would the

centre of gravity have to be raised least to over

turn it ?

Inf. 3 . Isatall °body more or less stable thanaShort body? Why ? (See Inf. 1andInf. 4. Isabodywithalarge base more or less

stable than onewithasmall base Why?I nf. 5 . Through what point of the base must the

line of direction pass that the bodymaybeas stableas possibleInf. 6 . Willabody stand if the line of direction

passes outside the base ?Inf. 7. The stabilityofabody resting on its base

depends upon what ?I nf. 8. Whyare legs of chairsand stools made to

slant outwardA young ladyplacedaStep ladder in the position

shown in Figure 13 ,and it stood .

Fig . 13 .



Call one Swing ofapendulumavibration .

Define.

Derive vibration .

b. CAUSE OF VIBRATION.

Inf. Inferwhat causesapendulum to vibrate.

c. RATE OF VIBRATION.

EFFECT OF LENGTH or AB C .

EXPERIMENT 48. (At h ome. )

Obs. 1 . Pull the pendulum three inchesaside, letgo,and count the vibrations for thirty seconds.

Obs. 2. Pull the pendulum six inchesaside, let go,and count the vibrations for thirty seconds.

Inf. Inferwhether the rate of vibration isaffectedby the length ofare through which the pendulum

swings.

EFFECT OF WEIGHT OF PENDULUM .


Obs. Suspendaheavier weight soas to makeapendulum of the same length ,and see howmanyvibrations itwillmake in th irtyseconds.

I nf. Infer whether the weight of the pendulumaffects the rate of vibration .

EFFECT or LENGTH OF PENDULUM .

EXPERIMENT (At h om e. )

Obs. 1 . Lengthen the pendulumand see howtherate of vibration isaffected .

GRAVITY. 51

Obs. 2. Make the pendulum four timesas longasat first,and see howthe rate of vibration isaffected .


Obs. 1 . By trial findapendulum of such length

that itwillmake one vibrationasecond.

Howlong is itObs. 2. Findapendulum that will vibrate half

seconds.

Howlong is it ?

USE OF THE PENDULUM .

1 . Howdoes the number of vibrations made byapendulum in one minute compare with the number

made inany other minute ?

2. Howthen, would you say the pendulum vi

brates3 . By reason of this fact it isadapted to what

use ?

Describe its useasametronome.

Derive metronome.

USE IN CLOCKS .

EXPERIM ENT 4 7 . (At sch ool. )

Windaclock,and start it. Notice howit goes foraminute or two.

Obs. Remove the handsand face of the clock,andobserve howthe pendulum is connected with the

works.


What is the tendency of the coiled spring ?

I nf. 2. What is the relation of the spring to the

worksInf. 3 . Inferwhatwould happen if therewere no

pendulum

Inf. 4 . Infer the use of the pendulum.

7. PRESSURE OF LI!UIDS.

a. FACT OF PRESSURE.

EXPERIMENT 4 8. (At sch ool.)

Over the large end ofasmall lamp ch imney tieapiece of sheet rubber suchas may be obtained ofadentist.

Fig . 14.

Fitacork stopper water-tight into the small endof the chimney.

Perforate the cork near one sidewitharat-tail file,and fit tightlyashort glass tube.

GRAVITY. 53

Drawthe other end of th is tubing over the tube of

asmall tunnel supported by means ofacrayon boxor stand,as in Figure 14 .

Loosen the stopperalittle so thatair may escape,and pour into the tunnel water enough to fill the

chimney, the tube,and the tunnel;and press the stop

per in tight.

Obs. 1 . Observe the effect upon the Sheet rubber.

Inf. 1. Infer the cause of th is.

b. DIRECTIONS OF PRESSURE.

Obs. 2. Keeping the sheet r ubberat the same distance belowthe level of the surface of thewater inthe tunnel, turn the chimney so that itwill be horizontal,and observe the effect upon the sheet rubber.

Do not claim to observewhat you infer.

Inf. 2. What causes th is ?Obs. 3 . Keeping the rubberat the same level, turn

the chimney so that the rubberwill be upward,andobserve.

I nf. 3 . Infer the cause.

I nf. 4 . Inwhat directions doeswaterat rest press?c. UPON WHAT PRESSURE DEPENDS .


Obs. Slowlylower the chimney farther belowth e

level of the surface of the water,and observe the

effect upon the sheet rubber.


Inf. What does pressure ofaliquidat rest dependupon ? i. e. howdoes it vary


In the gas oralcohol lamp flame, heatapiece of

small glass tubingabout two inches from the end,andwhen it becomes soft drawit out toapoint.

When it is cooled, break off the small end of the

two-inch piece, soas to leavean openingabout one

sixteenth ofan inch in diameter.

Fit the large end of this tube into the cork stopper

in the end of the chimney.

Obs. 1 . Fill the chimney, tube,and tunnel withwater,and observewhat thewater does.

Obs. 2. Lowerand raise the chimney,and observethe effect.

I nf. Infer the cause of thisaction .

d . SURFACE OF LI!UID IN COMMUNICATING VESSELS .


Remove the short, glass tube from the cork,and

insert oneabout two feet long.

Obs. 1 . Holding the chimneyand this long tube

upright, fill the chimney, rubber tube,and tunnel

with water,and observe the height of the water inthe glass tube.

Obs. 2. Slowly raiseand lower the tunnel, andcompare the height of the water in the glass tube

with its heigh t in the tunnel.

GRAVITY. 55

e. WATER WORKS FOR C ITIES AND TOWNS .

Describe with diagrams the water works of your

city or town,representing the pumping station, stand

pipe or reservoir, mains, hydrants,and p ipes inahouse.

Inf . 1 . Where is the presure in the pipes greatestI nf . 2. Howh igh willwater rise in the pipes ?

I nf . 3 . Wherewouldwater be thrown highest fromahose connected withahydrantf. THE SPIRIT LEVEL.

Examineaspirit level.Obs. 1 . Ofwhat parts does it consist ?The liquid in the tube isalcohol,and the bubble

isair.

I nf. Why isalcohol better thanwater ?Obs. 2. When the bubble is in the middle of the

tube,what is the position of the case ?1 . Howis the level used

g . SPRINGS AND WELLS.

What becomes of the water that falls upon the

landas rain ?The portion of it which sinks into the ground

works down through soil, loam, sand, or gravel,andcomes toalayer of material,aa’, in the diagram,

th rough which it does not readily pass.

Itworks itswayalong the slope of th is impervious

layer, through the loose materialwh ich rests upon it,and mayreach the surfaceat some lower level,asata’.


Call thewater flowing outat the surfaceaspring .

Suppose the water fills the loose material to the

level 0 c’.

1 . Ifahole is dug down through this material,asat w, what will fill the lower part of thehole

2. Towhat level?Call suchahole extending down belowthe level

of thewater in the earthaARTES IAN WELLS .

Sometimesalayer of loose material,as s s'

,

cluded between two layers of earth impervious to

water, is exposedat the surfacealong one edge,as

Fig . 16 .

at s',and stretches downan extended slope, perhapsfor many miles.



I nf. 2. Has the pebble gained or lost in weigh tbybeing immersed in thewater ? Howmuch ?Obs. 2. Remove the pail from the basin,and,again

holding the balance so that the pebble is immersed ,pour the water from the basin into the empty pail,and notice the effect upon the balance.

Fig . 17.

3 . Howdoes the weight of the inwater

, together with the weight of the water displaced, comparewith theweight of the pebble inair ?

GRAVITY. 59

Repeat th is experiment usingamass of iron in

place of the pebble.

I nf. 4 . Howdoes the loss of weight ofasolid

immersed compare with the weight of an equalvolume of the liquid ?

Inf. 5 . A solid having the sameweightas its ownvolume of the. liquidwill lose howmuch of itsweighton being immersed ?

Inf. 6 . Will it float, or sinkInf. 7. If itwill float,atwhat level?Inf . 8. Willabody heavier than water float inwater, or sink ?Inf . 9. Willabody lighter than water float, or

sink ?

Inf. 10. Will it projectabove the liquidInf. 11 . A body halfas heavyaswater will floatwith what part of itabovewater ?Inf. 12. Sinceapiece of sheet tin or of iron

sinks in water, howcanatin pan oran iron ship

float ?

i. SPECIFIC GRAVITY.

OF SOLIDS .

Divide theweight of the pebble inair, in the pre

ceding experiment, by the weight oian equal volumeof water.

Call the quotient the Specific gravity of the pebble.

Derive the term.


Find the specific gravity ofamass of iron weighingtwo or three pounds.

a. Think howyou can find theweight ofan equalvolume ofwater.

b. Think howyou can proceed to find the specific

gravityof the iron .

c. Find it .

1 . State howto find the specific gravityof solids

heavier thanwater.

Inf. 13 . Supposeabody floatswith half of its volume underwater,what is its specific gravity?I nf. 14 . If it floatswithan eighth of its volume

underwater,what is its specific gravity?Inf . 15. Ifabody floatswith five sixths of its vol

ume out ofwater,what is its specific gravityA convenient Spring balance for finding the specific gravityof small

Specimens of mineralsand metals maybe madeas follows.

Cut outapiece of board (pine orwhitewood)about 6 inches square,andanother pieceabout 16 inches long,and I!incheswideat one endand 1 inchat the other end .

Nail thewide end of this strip to the middle of one edge of the

square, so that itwill stand uprightwith the squareasabase,as Shownin the figure.

Near the top of this standard insert horizontallyascrew-eye of smallwire 15 inches long,with eye opened soas to formahook .

Makeaspring bywinding brasswire, No. 25 to 28, closeaboutapencil,and keeping itwound foraminute or two.

Hang the Spring byone end of the coilupon the hook .

B end the end of thewireat the lower end of the coil intoahorizontal position, so that it will projectasan index in front of the

standard .

Mark offascale upon th is standard from the level of the index

downward, bydrawing horizontal lines 115 ofan inchapartand num

bering everyfifth line.

GRAVITY . 61

By means ofanoose of horse hair or fine thread, suspend the

specimen from the lower end of the Spring,and see howmanydegreesit stretches the spring, i. e. howmanyunits ofweight it has.

Raiseatumbler partlyfilled with water under the specimen until

it is immersed,and thus get its loss ofweight inwater.

Fig . 18.

OF LIQUIDS .


Weighasmall-mouthed bottle.

Fill itwith waterandweigh it.

Fill itwith saturated brineandweighFind the specific gravityof the brine.

Find the specific gravity ofalcohol, linseed

oil,and of kerosene.


8. PRESSURE OF AIR.

a. FACT OF PRESSURE .


Over the mouth ofaT . D . clay pipe, tie,air-tight,apiece of sheet rubber.

Obs. 1 . Taking the stem of the pipe in the mouth .

with the bowl upright, drawout through the stem

as muchairas you can,and observe the effect upon

the sheet rubber.

Inf. 1 . Inferwhat causes this effect.

6 . DIRECTIONS OF PRESSURE.

Obs. 2. Turn the bowl of the pipe downward,out theair,and observe the effect.

I nf. 2. Infer the cause of this.

Repeat thiswith the bowl in various positions.

Inf. 3 . Inwhat directions does theair press ?

0. EFFECTS OF PRESSURE.

EXPERIM ENT 55 . (At h ome.)

Fillatumblerwith water, outapiece of card-boardalittle larger than the top of the tumbler,and lay itover the top.

With the palm of the hand hold itagainst the edge

of the tumbler without pressing the middle of it in,

invert the tumbler,and remove the hand .

GRAVITY. 68

Obs. Observe the effect.

I nf. Inferwhy thewater does not fall out.EXPERIMENT 56 . (At sch ool. )

Insertasmall glass tube in water,and note the

height of thewater in the tube.

Place the thumb over the top,and raise it verticallyout of thewater.

Obs. Observewhether thewater remains in the tubeInf. Infer the cause.


Fillatumbler with water, invert it under waterand, holding it even, raise it until the mouth is nearlyeven with the top of thewater.

Obs. Observe the height of thewater in the tumbler.

Inf. 1 . What sustains thewater there ‘

3

Inf. 2. What force causes the pressure of theair ?

BAROMETER.


Bymeans ofashort piece of rubber tubing, connectthe tube ofasmall glass tunnelwith one end ofaheavyglass tube 3 3 or 3 4 inches long,and closedatthe other end .

Fill the tubewith mercury.

If thereareair bubbles in the tube, remove them

by insertingaslender ironwire.

Holding the finger firmly over the end of the tube,


so that no mercury can run out, invert the tube,andinsert the open end of it inacup of mercury.

Obs. 1 . Notice the height of the mercury in the

tube.

I nf . 1 . Why does it notall run out of the

tube?

Inf. 2. Whydoes it not entirelyfill the tube?Obs. 2. Measure the height of the mercury

in the tubeabove the surface of the mercuryin the cup.

It is found by experiment that the height ofthe column of mercury is notafiecled by the size

of the tube, but varies slightly forall tubesatdifferent times.

Inf. 3 . What does the height of the mercurycolumn depend upon

? (See Inf. landInf. 4 . What does the variation in the height

of the mercury indicate ?Thus the height of the mercury column be

comesameasure of theatmospheric pressure.

For this use the tube isattached toacasewith agraduated scaleat the top to indicate the

height of the mercury column in inches ; and the

wholeapparatus is calledabarometer.

Describe it,and derive the name.

EXPERIM ENT 59. (At sch ool.)

Place the barometerwhere itwill not be disturbed,and note the changes in the height of the mercuryand the changes in theweather forafewweeks.



Getapiece of pine 10 inches longand g inch squareat one end,andat the other end 5 inch thickand wide enough to fill the spacebetween the screw-eyes.

Place thewide end of the rod between the screw-eyes,and fasten itby small screws passing through the screw-eyes, taking care to havethe end of the rod far enough from the spool toallowthe valve toopenat least 1 ofan inch .

Round off the rod withaknife,and wind upon the spool enough

twine toalittle more than fill it.

Fig . 20.

Fig. 21 . Fig. 22.

Call th isapparatus the piston of your pump.

Selectalamp ch imneysuchas is shown in Figure 21, of the samediameter throughout the straight part.

To test the evenness of chimneys fit the piston into themandworkit carefully upand down, noticing whether the fit is equally close

throughout.

Fit tightlyacork into the large end of the ch imney.

GRAVITY. 67

Perforate this corkwitharat-tail file,and fitaglass tube 8 or 10

inches long into itwater-tight,as shown in Figure 22.

Makeavalve covering the top of this tube like the valve in the topInsert the cork intowh ich the tube has been fitted in the large end

of the chimney.

W ithatriangular file makeahole through the side of the chimneyabout 2 inches from the top, then witharat-tail file round out the

hole soas to make it elliptical,and insert in itashort piece of rubber

tube foraspout.EXPERIMENT 6 1 . (At sch ool.)

Having made sure that the pistonand the corkaretight, take the chimney in the left handand the

piston rod in the right,and inserting the glass tubebelowthe surface of the water, carefully Work the

piston upand down .

Obs. 1 . Observe the position of each valveas thepiston is raised,andas it is lowered .

If no change is observed, work the piston faster,and notice carefully.

I nf. 1 . Infer the cause of the changes.

Obs. 2. Observe the change in thewater.

Inf. 2. Infer the cause of this changeNOTE . To say that thewater is “ drawn up, or sucked up, is

not givinganycause.

Ifapipe 3 3 feet or more in length , closedat one

endand openat the other, be filled with water,and,with the open end kept underwater, the closed end

be raised until it is brought toavertical position , ithas been found that thewaterwill continue to fill thepipe to the height ofabout 32 feetabove the level ofthe water outside of the pipe.


I nf. 3 . Infer what keeps the water up to thatheight.

Inf. 4 . Why does it not sustainah igher column

ofwater ?I nf . 5. About howhigh should you think water

could be raisedwithalifting pump ?Is it ever necessary to raise water higher than

that ?FORGE PUMP.

To MAKE A FORGE PUMP.

Fitarod‘

about 10 inches long intoaspool 1 inch in diameter,as inFigure 23 . W ind the spool full of twine,and selectalamp chimneyof even bore,as for the lifting pump .

Fig . 23 .

Fit the bottom of the chimneytightlywitha. firm cork,and fit thecorkwithatubeand valve,as in the lifting pump .

Fit tightlyafirm cork intoahorse-radish bottle.

Connect the lower part of the ch imneywith the bottle bya. glasstube, bentas shown in Figure 24,and fitted tightly into the stop

pers.

Over the end of th is tube in the bottle placeavalve like that in thech imney.

Makeanother hole in the cork in the bottleand fit into it tightlyaglass tube 5 or 6 inches long, bentas shown in the figure,and drawnout toasmall sizeat the end b, Figure 24 .


Having made sure that the piston , corks,and tubesareall tight, hold the ch imneyin the left hand, insert

GRAVITY. 69

the tubeaunderwater,andwork the plston carefullywith the right hand .

Obs. 1 . Observe theaction of each valveand the

movement of thewateras the piston raisedandasIt is pressed downward .

l . Infer the cause of each change observed .

Obs. 2. What is in the upper part of the bottle ?Call the bottleanair-chamber.

Inf. 2. Ofwhatadvantage is it ?


Inf. 3 . What kind of pump is usedatapumpingstation1 . What do fire-engines for throwing water con

sist of9

Writeaconnected description of each kind of

pump, illustrating by drawings.

SIMPLE MACHINES . 71

VI I . SIMPLE MACHINES.

1 . LEVERS.

a. DEFINITIONS.

LEVER.

EXPERIM ENT 6 3 . (At h ome.)

pencil or rule uponabook so thatprojectabout 3 inches beyond the

By raisingand lowering the ends of the pencil,

turn itabout the edge of the bookasafixed support.

Callabar soarrangedalever.

Define.

Derive the term .

FULCRUM .

Call the support upon which it turns the fulcrumof the lever.

Define.

Derivefulcrum.

LOAD AND POWER.

EXPERIMENT 6 4 . (At h ome. )

Placeanother book upon the projecting end of the

lever,and press downwith the fingers upon the other

end.



Call the second book the load of the lever.

Call the forceapplied to support the load thepower.

1. In theabove experimentwhatwas the positionof the fulcrumwith reference to the loadandthe power

2. Use your pencilasaleverwith the load betweenthe powerand the fulcrum .

3 . Use itasalever with the power between the

loadand the fulcrum.

b. RELATION OF POWER TO LOAD.

EXPERIM ENT 6 5 . (At sch ool. )

Insertasmall screw-eye in the middle ofalightwooden bar 13 inches long .

Suspend the bar by this screw-eye from the middle

of the frame used in Experiment 3 6 .

Fig. 26 .

If the bar does not balance inahorizontal position,whittle down the heavierarm until it does.



Obs. 2. Applied 4 inches from the fulcrum,itwill

balancewhat load 2 inches from the fulcrum ?

Obs. 3 . Applied 6 inches from the fulcrum,itwill

balancewhat load 2 inches from the fulcrum ?

EXPERI MENT 6 7 . (At sch ool.)

Obs. Place the load twiceas far from the fulcrum

as in the last experiment,and see howthe powerrequiredatanypoint to balance it isaffected:

0. APPLICATIONS .

CROW-BAR.

Describe the crow-barand its use.

STEELYARD.

Showwhere the fulcrum is in the steelyard.

Where the load isapplied .

Where the power isapplied .

Howtheweight of the load is shown .

2. WHEEL AND AXLE.

a. CONSTRUCTION.

The wheeland axle consists of two connected

cylinders of different diameters turning uponacommonaxis,as Shown in Figure 27.

The larger cylinder is called the wheel, and the

smaller one theaxle.

SIMPLE MACHINES. 75

Ih'

g . 27.

Thewheelandaxle maybe madeas followsGetaturner to turn for you in one piece two cylinders, each 1 inch

long,and one 1 inchand the other 3 inches in diameter,as shown in

Figure 28.

At the inner end of the smaller cylinder drivealarge gimp tack,allowing the head to projectalittle.

Fig . 28.

In the middle of the opposite side of the larger cylinder driveasmall gimp tack .

Makea. small holewithanawl in theaxis of the cylindersat eachand .

Cut outapiece of board 4 inches long,and 3 incheswideat one endand 1 inchat,the other. Th is piece ismarkedain Figure 27.

Place this piece in position,as Shown in the figure, 2}inches fromthe end of the frame

,and fasten itwith screws through the top of the

frame.


Withanawl makea. horizontal hole halfan inchabove the middlepoint of the lower end of this piece,andanother hole in the same linewith this, in the end of the frame.

Place thewheelandaxle in position,and fasten it byinserting wirenails through the holes in the frame into the ends of the cylinders.

If it does not turn easilypull out thewire nailsand make the holesin the framea. little larger.

6. RELATION OF POWER TO LOAD.

Tieastring 12 inches long to the tack in the

wheel,andanother to the tack in theaxle.

In experimenting, let these strings drawaroundthe wheelandaxle in opposite directions.

EXPERIM ENT 5 8. (At sch ool.)

Obs. l. Hangaload of 6 units upon the string

on theaxle,and find what powerapplied to the

string on the wheel will balance it.Obs. 2. Findwhat powerwill raise it.

Obs. 3 . In moving the load 1 inch the powermoves howfar ?1 . The load isapplied howfar from theaxis ?2. The power isapplied howfar from theaxis ?Inf. l. Theaxis of thewheelandaxle corresponds

towhat in the lever ?

I nf. 2. The radius of theaxle in this experiment

corresponds towhat in the lever ?I nf. 3 . The radius of the wheel corresponds to

what in the lever ?

In theabove experiment the power wasappliedtimesas far from theaxisas the load,anda

SIMPLE MACHINES. 77

power as greatas the load was required to

balance it.

Inf. 4 . Howdoes the relation of power to load inthe wheelandaxle compare with the relation of

power to load in the lever

I nf. 5 . Howfar canaload be movedwith oneapplication of the lever ?

Inf. 6 . Howfarwith oneapplication of thewheelandaxle ?Inf. 7. Whatadvantage has the wheelandaxle

over the lever ?

Inf. 8. Forwhat uses is the lever betteradapted

EXPERIM ENT 69. (At sch ool.)

Placeaload of 3 units upon thewheel.Obs. 1 . Find what powerapplied on theaxlewill

balance it.

Obs. 2. Findwhat powerwillmove it.

Obs. 3 . In raising the load 6 inches howfar doesthe power move ?1 . Howdo these results comparewith those oh

tained witli the lever ?

c. APPLICATIONS .

What uses ofany form ofwheelandaxle have youseen

Writeacomposition upon the Uses of the WheelandAxle, illustrating the various forms by drawings.


3 . PULLEYS.

a. DESCRIBE .

Examine one of the pulleys in the framewhich wehave used,and tellwhat it consists of.

FIXED PULLEY .

Callapulley wh ich remains in the same placewhen in useafixed pulley.

MOVAB LE PULLEY .

Callapulleywhich changes its placewhen in useamovable pulley.

A good set of pulleys is desirable. If theseare not to be had , brasspulleys carefullyselected from suchas maybe foundatanyhardwarestore,andat many country stores,will do.

Toadapt these for useasmovable pulleyswind one end ofapieceof

113- inch wire 8 inches longabout the shaft just belowthe pulley.

Bend the wire over the pulley,as shown in Figure 29,wind it downaround the shaft,and bend the end intoahook .

Fig . 29

SIMPLE MACHINES. 79


IN FIXED PULLEYS .


Drawapliable string overafixed pulley.

Fastenaload of 6 units to one end of the string .

Obs. 1 . Findwhat powerappliedat the other endwill balance it.

Obs. 2. Findwhat powerwill raise it.

Inf Why isagreater power required to raiseaload than to balance it ?

EXPERIM ENT 71 . (At sch ool.)

Pass the cord over three fixed pulleys,as shownin Figure 3 0.

Fig . 3 0.

Hangaload upon one end of the cord.

063 . Findwhat powerappliedat the other endwillbalance it.


Inf. Inferwhat powerwill balanceany loadwhenacting throughacord passing overany number of

fixed pulleys.

IN COMB INATIONS or FIXED AND MOVAB LE PULLEYS .


Fasten one end of the string to the top of the

frame.

Drawthe other end underamovable pulleyandoverafixed pulley,as indicated in Figure 3 1 .

Fasten to the stringaweight which will balancetheweight of the movable

Fig . 3 1 .

Hangaload of 2 pounds on the movable pulley.

Obs. 1. Findwhat powerwillbalance it.

1 . Compare the powerand load.

Obs. 2. The movable pulley is supported by howmany parts of the cord ?



4. INCLINED PLANE.

Getapiece of board 6 x 24 inches.

Fastenapulley in the middle of one end of it,asshown in Figure 3 3 .

Place the board uponatablewith the pulleypro

jecting 3 inches beyond the end of the table.

Fig . 3 8.

Raise the end containing the pulley4 inches higherthan the other end of the board,and support itwithbooks placed under it.

Call the top of this boardan inclined p lane.

0. RELATION OF POWER TO LOAD.


Upon this plane placeatoycar or carriagewithastring fastened to itand passing over the pulley.

Obs. 1 . Let go the string,and observe the effect.

Balance the car byaweight upon the string.

Place upon the caracan or box of pebblesweighing 3 pounds.

SIMPLE MACHINES. 83

Obs. 2. Findwhat powerappliedat the end of the

stringwill balance th is load .

1 . Howdoes it comparewith the load ?2. Howdoes the height of the plane comparewith

the length of the planeI nf. Inferwhy the power required is less than the

load .


Raise the end of the inclined plane 4 inches h igher ;and repeat the experiment, comparing the powerwiththe loadand the height of the planewith its length .

b. USE.

1 . Where have you seen inclined planes used for

raising loads?Inf. Ofwhatadvantageare they?

5 . SCREW .

It iswell for the school to ownasmall jack-screwor bench-screw. If that is not practicable, one maybe borrowed of some mechanic or building mover.

1 . Turn the screwpartly out of the nut,and ex

amine it. What is its general shape ?2. What is there upon the Outside of this cylinder ?

Call this spiral projection the thread Of the screw.

3 . Notice the upperand lower surfaces of the

threadas theywindaround the cylinder.

Are theylevel, or inclined ?

What do theyform ?


4 . Remove the screwand examine the inside of

the nut.

What do you find for the thread of the screwtofit into ?

Figure 3 4 representsajack-screwas it wouldappear if the front half of the upper part of the nut

could be removed, showingavertical section of the

nutand the front of the screw.

Fig . 3 4 .

5. What does the screwrest upon ?

6 . What does the under side of the threadoverwhen the screwis turned ?

See ifyou can raiseaload withajack-screw.

Explain fullyby diagram howit is done.

SIMPLE MACHINES. 35

6. WEDGE

Examineawedge.

1 . Compare itwith the inclined plane.

2. Forwhat have you seen it used ?

3 . In its use is the load moved over thewedge ?4 . What ismoved ?5. Howis it moved ?

APPLICATIONS OF THE SIMPLE MACHINES .

1. Which of these machines have you seen used

in raising loads to the upper stories of

buildings

2. A door key belongs to which of these classesof machines?

3 . Which machines have you seen used for raisingand lowering the wicks of lamps?

Which would you use for splittingwood ?Which is used in movingabuildingalong the

street ?

6 . What other simple machine is used in workingajack-screw?7. What machinewould youuse in loadingabarrel

of Oiluponatruck ?What machines have been used for raising the

Old oaken bucket from thewell?9. In which of the Simple mach ines is the re

sistance of friction least ?Canany machine furnish energy?


Writean explanation of theadvantages in the use

of simple machines, giving examplesand illustratingby diagrams. Showthat :1 . They enable us to do slowly heavierwork thanwe could do without them, or to do ligh t

work more rap idly than we could withoutthem.

2. They enable us to useaforceatamore con

venient pointand inamore convenient di

rection than we could otherwise use -it.

3 . They enable us to employ other forces than our

own in doing work .

HEAT. 87

VIII . HEAT.

1. SOURCES OF HEAT.

EXPERIMENT 76 . (At h ome .)

Obs. Hold the back of your hand in the sunshine

foraminute,and then in the Shade,and notice the

difference.

Inf. What is one source of heat ?EXPERIM ENT 77 . (At h ome.)

Repeat Experiment 21 .

I nf. What isanother source of heat ?EXPERIMENT 78. (At h ome.)

Touchanail to your cheek .

Hammer one end of it uponananvil forafewseconds,and touch it to the cheekagain .

Obs. Observe the change.

Inf. 1 . Inferath ird source of heat.

In our studyof Correlation of Forceswe noticed twoother sources of heat.

1 . Whatare they?2. Name the sources of heatwh ich we have con

Sidered .

Inf. 2. From wh ich of these sources do we getmost heat ?Inf. 3 . From which do we get the next greatest

supply?


2. EFFECTS OF HEAT.

0. EXPANSION.

(1) OF SOLIDS .


Bend one end ofawire 10 inches long intoaringjust large enough so thatamarble will not drop

through it.

Obs. 1. Heat the ring hot,and see if the marblewill drop through .


Inf. 2. What is one effect of heat ?Derive the term eapansion .

Obs. 2. Cool the ring,and see if the marble willdrop through .

Inf. 3 . Infer the cause of this.

1 . Give other instances in which you have noticed

that heat expands solids.

2. In laying the rails ofarailroad whatallowanceismade onaccount of this fact?

3 . Do you knowofany uses made of this fact inthearts?

(2) OF LI!UIDS .

EXPERIM ENT 80.

Fillalarge test tubewith cold water.

Insertastopper intowh ich has been fittedasmall



(3 ) Or GASES .

EXPERIMENT 82. (At sch ool. )

Fill theapparatus used in Experiment 80withair,insert the glass tube beneath the surface of water,and warm the test tube.

Obs. What is the effect

Inf. What causes thisaction ?1 . What effect of heat is Shown in Experiments

79, 80, 81,and 82 ?6. CHANGES IN STATES OF MATTER.

Liquefaction.

EXPERI MENT 83 . (At h ome .)

Heatalittle ice inatin can or cup.

Obs. State the cfiect,and give aname to the

change.

Derive the name.

I nf What would be the effect if this heat weregiven out from the water ?The change ofaliquid toasolid is called solidi

fication.

Derive solidification.


Heatalittle lead inan iron spoon .

Obs. 1 . Observe the change.

Obs. 2. Allowthe lead to cool,and observe the

change.

HEAT. 91

1 . Give other instances in which heat changes thestate of matter.

EFFECT OF MELTING ON ADJACENT B ODIES .


Inatin can mix ice, broken into small pieces,withabout half itsweight of salt.

Obs. 1 . Watch the change forafewminutes.

Obs. 2. Then insert your finger in the mixture,and note the temperature.

Intoasmall test tube pourafewdrops ofwater.

Insert it in the mixture,and leave it forafewminutes.

Obs. 3 . Observe the effect on thewater in the testtube.

Inf. 1 . Infer the cause of this change.

I nf. 2. Infer the effect of melting uponadjacentbodies.

1 . What use is made of th is fact ?Inf. 3 . What effect does the melting of iceand

snowhave upon the temperature of theairVaporization .

BOILING.

EXPERI MENT 86 . (At sch ool.)

Half fillatest tube with water,and heat it carefully by holding it obliquely in the flame for 5

minutes.



(3 ) Or GASES.


Fill theapparatus used in Experiment 80withaninsert the glass tube beneath the surface of water

,and warm the test tube.

Obs. What is the effectI nf. What causes th isaction ?1 . What effect of heat is Shown in Experiments

79, 80, 81,and 82 ?b. CHANGES IN STATES OF MATTER.

Liquefaction.

EXPERIM ENT 83 . (At h ome . )


Obs. State the effect,and give aname to the

change.

Derive the name.

Inf. What would be the effect if this heat weregiven out from the water ?The change ofaliquid toasolid is called solidi

fication .


EXPERD I ENT 84 . (At sch ool.)



Obs. 2. Allowthe lead to cool, and observe the

change.

HEAT. 91

1 . Give other instances inwh ich heat changes thestate of matter.

EFFECT OF MELTING ON ADJACENT BODIES.








I nf. 1 . Infer the cause of this change.


1 . What use is made of th is factInf. 3 . What effect does the melting of iceand


BOILING.



minutes.


(3 ) OF GASES.


Fill theapparatus used in Experiment 80withalrinsert the glass tube beneath the surface of water,and warm the test tube.

Obs. What is the effectI nf. What causes th isaction ?1 . What effect of heat is Shown in Experiments


Liquefaction.



Obs. State the effect,and give aname to th e

change.

Derive the name.

I nf. What would be the effect if this heat weregiven out from the water ?The change ofaliquid toasolid is called solidi

fication .


EXPERD I ENT 84 . (At sch ool. )




change.



(3 ) OF GASES.


Fill theapparatus used in Experiment 80withair,insert the glass tube beneath the surface of water

,and warm the test tube.


I nf. What causes th isaction ?1 . What effect of heat is shown in Experiments


Liquefaction.




change.

Derive the name.

I nf. What would be the effect if this heat weregiven out from the water ?The change ofaliquid toasolid is called solidi

fication .


EXPERIM ENT 84 . (At sch ool. )




HEAT. 91

1 . Give other instances in which heat changes thestate of matter.

EFFECT OF MELTING ON ADJACENT BODIES.








I nf. 1 . Infer the cause of th is change.


1 . What use ismade of this fact ?Inf. 3 . What effect does the melting of iceand


BOILING.



minutes.


(3 ) OF GASES.


Fill theapparatus used in Experiment 80withair,insert the glass tube beneath the surface of water,and warm the test tube.


I nf. What causes th isaction ?1 . What effect of heat is Shown in Experiments


Liquefaction.




change.

Derive the name.

Inf. What would be the effect if this heat weregiven out from the water ?The change ofaliquid toasolid is called solidi

fication .

Derive solidification .







Obs. 1 . Observewhat rises from the tube,and thequantity ofwater left in the tube.

Inf. Inferwhat change in the state of matterwasproduced .

Call this change vaporization .

Derive the term .

Obs. 2. Describe carefully the processas it occursin this experiment.

What is formedwith in the liquid Rapidly Or slowlyCall this processNOTE . Some pupilsmay tryadditional experiments to determine

the boiling points of different liquids,and what the boiling point ofany liquid depends upon .

EVAPORATION.


Placealittlewater inaShallowtin plate,and heatit gently,without boiling , for halfan hour.

Obs. Observe what forms,and the quantity of

water remaining .

Inf. Inferwhat change is taking place.

1 . Howdoes the process differ from boiling ?

Call it evaporation .

Derive the name.

NOTE . Some pupils may investigate the influences whichevaporation.

EFFECT OF VAPORIZATION ON ADJACENT B ODIES .


Placeadrop ofwater onapiece of Shaving .

On the drop restathinwatch crystalwithadrops of ether in it.

HEAT. 93

With the mouth about 8 inches from the ether,

blow steadilyacross its surface until it has allevaporated .

Obs. Observe the effect upon thewater under the

crystal.Inf. 1 . Infer the cause of th is change.

1 . Howdoes sprinkling the floor or the street

afiect the temperature of theair ?2. Howdoesasummer showerafiect the temperature ?I nf. 2. Why?Explain the manufacture ofartificial ice.

CONDENSATION,


Obs. Vaporize some water, holdapiece of cold

glass in the escaping vapor,and observe the effect.

Inf. Infer the cause of this.

1 . What newchange in the state ofmatter occurs

in th is experiment ?

Name the change condensation .

Derive the name.

DEw, DEwPOINT, FROST, CLOUDS, RAIN, HAIL, SNOW .


Half fillatin fruit can with wateratatemperature ofabout 60 degrees.

PlaceaChemical themometer in thewater,andaddsmall bits of ice gradually until moisture begins to

collect on the outside of the can.


Call thismoisture dew.

Call the temperatureat which it begins to formthe dewpoint.I nf. 1 . Infer the cause of the deposit.

I nf. 2. Account for the dewon the grass.

I nf. 3 . Account for frost.I nf. 4 . If coldair meets warmair, what is the

effect upon the warmair ?I nf. 5. Upon the moisture in theair ?I nf. 6 . Infer how“

rain is formed ; hail;3 . TRANSFER OF HEAT.

0 . RADIATION.


Hold your hand forafewseconds nearahot stoveorany heated bodyObs. Observe the effect upon it.

Infer the cause of this.


Obs. Hold the hand in various directions from the

heated body,and observe the effect.

Infer in what directions heat passes from

heated bodies.


Obs. Placing the hand in the same positionsas before

,holdasheet of paper between itand the heated

body,and Observe the result.

I nf. 1 . Infer in What kind of lines heat passesfrom heated bodies.



USES OF POOR CONDUCTORS .EXPERIMENT 99. (At h omo.)

Keepablock of oak wood, of pine wood,and of

iron,aroll of cotton cloth , of woollen cloth ,and of

silk cloth ,andathermometer, near together forafewhours inaroom where the temperature does not

change much .

Obs. 1 . Then test the temperature of these bodies

with the thermometer, keeping it on each forafewminutes.

Obs. 2. Touch them successively to the cheek,and

see if theyall feel equallywarm.

Inf: 1 . Infer the cause of the difierences.

Inf. 2. Why is clothing necessary?I nf. 3 . What is the best material for clothing ?1 . Mention other uses of poor conductors.

WATER AS A CONDUCTOR.


Takeatest tube nearly full ofwater,and, holdingit by the lower part, heat it just belowthe surfaceof the water until the water begins to boil.Obs. Observe the temperature of the lower part of

the tube.

I nf. Inferwhat kind ofaconductorwater is.

Airalso isapoor conductor.

What use is made of th is fact in constructing

housesand refrigerators ?

HEAT. 97

WEIGHT OF HOT AND COLD WATER.

EXPERIM ENT 98.

Fillasmall canwith cold water,and balance it onascale pan .

Pour out the coldwaterand fillwith hot.Obs. Place the can on the scale pan,and compare

itsweightwith that of the can of coldwater.

Inf. Infer the cause of th is difference.

(3 . CONVECTION.

EXPERIM ENT 99. (At h om e.)

Takeacake pan two thirds full ofwater,and mixalittle fine sawdustwith it.

Heat it gently in one place byaflame below.

Obs. Observe the effect in thewater.

Inf. 1 . Howcan you explain thismovement ?Call this mode of distributing heat convection .

Derive convection.

Inf. 2. Explain howocean currentsare produced .


Fitabroken test tubeabout 4 inches longwith astopper.

Into this fitapiece of glass tubing (b c in Figure4 inches long .

Bendanother piece of tubing , 15 inches long,asshown in Figure 3 7,ab,and fit it into the stopper so

that itwill reach one inchabove the other tube.

Connect these tubesat b byapiece of rubber

tubing .


Setacrayon box upon one side,and placeanotherbox upon this in the same position .

Cut Slots in the edges of these boxes for the tubes

to pass through , so that the test tube may rest upon

the upper box .

Fig . 3 7.

Pour water slowly into the test tube until it is

nearly filled,andaddalittle fine sawdust.

Heat the slanting portion of the tubewithacandleflame.

Obs. Observeanymovement of thewater.

Inf. Explainwhat causes it.



Obs. 1 . Observe the quantity ofwater in the flaskand in the can,and the temperature Of thewater inthe can .

Do you think the water in the flask has been

growing hotter ?

Obs. 2. Open the flask,and test it.

I nf. 1 . What became of the heatappliedI nf . 2. What became of the vapor formed ?I nf. 3 . What became of the latent heatwhen th is

vaporwas condensed ?Inf. 4 . Explain by diagram the process of heating

by steam.

Some pupils may constructapparatus illustratingthis subject.


In one test tube place some fine ice or snow,and inanotheran equalweight ofwater.

Obs. 1 . Notice the temperature of each .

Obs. 2. Insert both inacan of hotwater until theice is nearlymelted,and observe the temperature of

each .

I nf. 1 . Infer the cause of the difference.

I nf. 2. If no heatwereabsorbedas latent heat inmelting, howlongwould it take the deepest snowor

the thickest ice to melt ?

Makeatopical outline of these lessons on heat.Write upon some of the topics.

MAGNETISM. 103

IX MAGNETISH .

1 . MAGNETS.

Repeat Experiment 18.

Callabodywhich has this force in itamagnet.Derive the termsmagnetand magnetism.

a. FORMS OF MAGNETS .

Three forms ofmagnetsare in common use.

Horse-shoe

o. KINDS OF MAGNETS.

TEMPORARY .


Bringamagnet in contact withanail,and this

nail in contact withanother nail.Obs. 1 . Observe the effect.

Inf. 1 . What has the first nail become ?Obs. 2. Separate the first nail from the magnet,and observe the effect.

Inf. 2. What kind ofamagnetwould you call thenailI . Howwas it produced ?Derive the name.


Rub one end ofamagnetalongasteelwire or

watch spring,always in the same direction .

Obs. 1. Then touch the wire to some iron filingsand Obwrve the effect.

Inf. 1 . What has it becomeObs. 2. Touch it to some ironafewminutes later.

Inf. 2. What kind ofamagnet is it ?I . DO you observe theanswer to this question, or

2. Howwas thismagnet produced ?

c. POLES OF A MAGNET.


filings over one side ofamagnet.

Raise itand turn it over, or hold it upright.



Fig . 42.

Obs. 2. Change the direction of the needle,andObserve.

Inf. What controls its direction ?EXPERIMENT 1 18. (At sch ool. )

Remove the bar magnet,and observe the direction

of the needle when it comes to rest.

I nf. What influences the needle’s direction now?

Call th is influence of the earth upon magnets terrestrial magnetism .

Derive terrestrial.b. MAGNETIC DECLINATION.

1 . Compare carefully the direction of the magneticneedle with that ofanorthand south line.

Call theangle formed byanorthand south line

and the direction of the magnetic needle magneticdeclination, or the variation of the needle.

Derive declination .

Describe the mariner’s compassand its use.

FRICTIONAL OR STATIC ELECTRICITY . 107

X. FRICTIONAL OR STATIC ELECTRICTY.

1 . HOW EXCITED .

For successfulwork in th is subject bright, clear, cold weatherandwarm, dryapparatusare necessary.

EXPERIM ENT 1 14 . (At h om e. )

HoldaSilk ribbonafoot long near thewall ofaroom .

Obs. 1 . See ifany peculiar result follows.

Drawthe ribbon between two layers ofawarmflannel padwith considerable friction,and hold it nearthewall.Obs. 2. Observe the efiect.

Inf. Infer the cause of thisaction .

EXPERIMENT 1 15 . (At h om e. )

Warmasheet of paper,and hold it near thewallofaroom.

Obs. 1 . See ifany peculiar result follows.

Place the paper upon awarm board,and rub it

brisklywith Indiarubber.

Obs. 2. Hold it near the wall,and observe the

effect.

Inf. Infer the cause.


EXPERIMENT 1 1 6 . (At sch ool.)

Rubastick of sealing waxwithaflannel pad,andbring thewax near bits of paper.




Call the forcewh ich produces efiectsfrictionalstatic electricity.

1 . Howwas it excited ?2. ELECTROSCOPES.

a. PITH—BALL.

EXPERIM ENT 1 1 7 . (At sch ool.)

Bendawire 6 inches long intoarightangleat itsmiddle point,and insert one end of it in the cork

stopper ofabottleas shown in Figure 43 .

Fig . 43 .

From the outer end of thewire suspend two pithballs, one quarter ofan inch or more in diameter,byaSilk thread .

Obs. Bring the excited chimney near the pith -balls,and observe the efiect.

Call thisapparatusap ith-ball electroscope.



EXPERIMENT 180.

Let one pupil excite the lamp chimneyandanotherthe sealing wax,and hold them foraminute or twoaboutan inchapart,with the pith -balls between them .

Obs. Observewhat happens.

Inf. Howcan youaccount for thisaction of the

pith-balls

EXPERIMENT 181 .

Repeat the last two experiments, using thebalancedbar instead of the pith

-balls.

Call the electricity excited in the lamp ch imney

positive and that excited in the sealing waxnegative

EXPERIMENT 188.

Findwhat kind of electricity is excited in the Silk

pad,andwhat kind in the flannel pad .

EXPERIMENT 1 83 .

Bendawire 12 inches long into the shape Shownin Figure 45,and suspend it byaSilk thread.

Fig. 45 .

FRICTIONAL OR STATIC ELECTRICITY. 111

Let one pupil excitealamp chimneyandanotherasecond one.

Obs. 1 . Lay one of the ch imneys upon the wirehooks, bring the other near one end of this,andobserve the efiect.

Obs. 2. Repeat th is experiment, using two sticks

of sealing wax in place of the ch imneys.

Obs. 3 . Repeat, using one chimneyand one stick

of sealing wax,and observe the effect.

Inf. Infer howbodies chargedwith the same kindof electricityaffect each other,and howthose chargedwith unlike electricitiesaffect each other.

5. CONDUCTION.

CONDUCTORS AND INSULATORS.


Layapiece of glass tubing 1 foot longacross the topofatumbler SO that one end of it will come with inabout one eighth ofan inch of one end of the balancedbar.

Obs. 1 . Touch the excited chimney to the end of

the tube remote from the electroscope,and see if the

bar isaffected .

Obs. 2. Try the excited sealingwax in place of thechimney.


Repeat Experiment 124, usingahard-wood foot rulein place of the glass tube.



Repeat, using your lead pencil.Repeatagain, usingakey.

Inf. 1. Inferan explanation of the facts Observed

in Experiments 124 to 126 .

Call theaction of electricity overabody con

duction.

Calla. bodyoverwhich electricityactsaconductor,and one overwhich it does notactan insulator.

Name the conductorsand insulators which you

have found in these experiments.

Inf. 2. Infer why glass bottlesare used in the

electroscopes.

Inf. 3 . Infer why the pith-balls fly offafter con

tact withan electrified body,and why they repel

each other.

Inf. 4 . Infer the use of lightning rods.

6 . INDUCTION.

l

EXPERIM ENT 1 27 . (At h ome.)

Supportacylindrical tin box, or can, with the

cover on, horizontally upon adry tumbler, so thatone end of the can will bewithinaquarter ofaninch of the bar electroscope.

Bring the excited ch imney or sealingwax near theother end of the can,without contact.

Obs. Observe the effect upon the electroscope.

Itmaybe best to omit this topicwith classes in grammar schools.



XI . VOLTAIC OR CURRENT ELECTRICITY.

1 . VOLTAIC ELEMENT.

EXPERIMENT 188.


Call thisapparatusaVoltaic element.

1 . What does it consist of ?

2. HOW PRODUCED.

Inf. Infer howthe electricitywas produced in theabove experiment.

3 . EFFECTS.

The effectsandapplications of electricityare toonumerousand varied to be considered, even in the

briefest way, in these Lessons. They formasubjectfor investigation in the latter part of the High Schoolcourse.

Butwewill recall briefly two or three effectswhichwe havealready noticed .

a. MAGNETIC .

1 . What effect of Voltaic electricity have youalready observed ?

VOLTAIC OR CURRENT ELECTRICITY. 115


Windabout 30feet of insulated No. 22 copperwirearoundasmall rod of soft iron 5 or 6 inches long ,

and connect the endswith the plates of the Voltaicelement.

Fig . 46 .

Obs. 1 . Bring bits of iron near one end of the iron

rod,and observe the effect.

Obs. 2. Bring them near the other end,and oh

serve.

Inf. l . Inferwhat the rod has become.

Inf. 2. Infer howthis changewas produced.

Obs. 3 . Separate one end of the wire from the

plate,and see if the rod retains its magnetism.

Obs. 4 . Hold the end of thewire to the plate,andsee if the rod is nowamagnet.Obs. 5. Touchaverysmall tack to the rod, sepa

rate the wire from the plate,and see howlong thetack is held.


Inf. 3 . Howlong does the rod continueamagnetafter the connection between the plates is broken ?Call the iron rodan electromagnet.Pupilsare nowprepared to examineand describe the keyand receiver

of the telegraph,and the electric belland press-button .

The keyand press-buttonare used to makeand break connections

and the receiver, or sounder,and the bell areapplications of electromagnets.

The constructionandworking of the telegraphand the electric bellmaybe described bythe pupils inwriting.

1 . What two effects of Voltaic electricityhave youlearned

b. THERMAL.

EXPERIM ENT 1 3 0. (At sch ool.)

Cut the connecting wire ofaGrenet battery,andtwistaround the endsapiece of fine platinumwire so

that there will beabout one inch of it between the

ends of the copper wire.

Obs. Lower the zinc plate,and test the temperatureof the platinum wire.

Inf. Infer howthe change has been produced.

0. LUMINOUS.

1. Howare incandescent electric lights produced ?2. What other luminous effects of electricity have

you noticed ?

Prepareatopical outline of these lessons in Electricity,andwrite upon some of the topics.



2. TRANSMISSION OF VIBRATIONS.

a. THROUGH WOOD.

EXPERIM ENT 1 3 4 . (At h ome.)

Holdalath horizontal,with one end resting lightlyagainst the panel ofadoor.

Makeatuning-fork vibrate,and press the end of

its handleagainst the free end of the lath . (A steel

table-forkwill do. )Obs. Observewhere the sound seems to come from.

Inf. Infer howthe vibrations reached the door.

6. THROUGH A STRING .

EXPERIMENT 1 3 5 . (At h ome.)

Punchalittle hole through the centre of the cover

and bottom ofacylindrical tin box .

From the outside insert one end ofastring 10or

12 feet long through the hole in the cover, andthe other end through the hole in the bottom . Tie

knots in the ends to keep them from pulling out.

Let one person hold the open end of the box to h is

ear,andanother person hold the cover far enoughaway to straighten the string, and sounding the

tuning-fork (or table-fork), touch the handle to the

box cover.

Obs. 1 . The one holding the box to the ear reportthe effect.

Obs. 2. Where did the sound seem to come from ?

Inf. Infer howthe vibrations reached the box.

SOUND. 119

c. THROUGH THE AIR.

EXPERIM ENT 1 3 6 . (At h ome. )

Layap iece ofwriting paper over the mouth ofatumbler, leavingan opening halfan inch or less in

width ,and trim off the outside of the paper so thatit will not project more than halfan inch beyond

the edge of the tumbler.

Press the paper down against the tumbler, andsprinklealittle fine sand on it.

Obs. Singastrong, full tone,and, slowly raisingand lowering the pitch , watch the sand upon the

paper.

If the sand is notaffected, change the Size of the

opening Slightly,and repeat until it isaffected .

I nf. 1 . Infer howth is effect is produced.

I nf. 2. Infer howthe Vibrations reached the paper.

In the ear isalittle membrane, stretched overabony framework,and forming the “ drum of the

ear, with which theair comes in contact.

I nf. 3 . Infer howit will beaffectedwhen objectsnear usare made to vibrate.

These vibrations continuing, reach the auditorynerve,and the sound is heard .

1 . What have you observed thatwould indicateatwhat rate sound is transmitted th roughair ?

Planan experimentwh ich will Showapproximatelythe velocity of sound inair.


3 . VIBRATING STRINGS.

a. LOUDNESS OF TONES .

EXPERIMENT 1 3 7. (At sch ool. )

Stretchaviolin string overasonometer.

Derive sonometer.

With the finger press the stringalittle to one side,and then let it Slip.

Obs. 1 . Observe the effect.

Press the string farther to one Side,and let it slip.

Obs. 2. Notice the distance wh ich the string vie

brates,and the loudness of the tone.

Obs. 3 . Press the string still farther,and observe.



Move the block Inward soas to Shorten the vibrating string,and repeat the experiment.

1 . Compare the pitch of the tonewith of the

tone of the longer string .

2. Shorten the vibrating string more,and repeatthe experiment.

Inf. Infer howthe tone isaffected by theof the string .


Soundastring 16 inches long,and then one8inches

longand stretchedwith the same force.

Compare the tones.


Stretchastring slightlywith the hand.

Obs. 1 . Sound it,and Observe its pitch .

Obs. 2. Stretch italittle harder,and repeat theexperiment.

Obs. 3 . Stretch it still harder,and repeat.

Inf. Infer howthe tone isaffected by increasingthe stretching force of the string .

EXPERIM ENT 1 4 8. (At sch ool.)

Stretchastring 8 or 10 inches longwithaforce of1 pound .

Sound the string,and note its pitch .

Stretch the stringwithaweight of 4 pounds,andrepeat.

1 . Compare the pitches of these tones.

SOUND.

2. What three things have we learnedaffect thepitch of tones produced by vibrating strings ?

3 . What strings give high tones ?4 . What strings give lowtones ?5. Howare the strings ofapiano varied to produce

the different tones desired ?

6 . Howare pianos tuned ?Repeat experiments 13 9- 142, noticing carefullythe rate of vibration

in each case,and see if you can decidewhat the pitch ofatone reallydepends upon.

4 . VIBRATING COLUMNS OF AIR.

EXPERIMENT 1 4 3 . (At sch ool. )

Get or makean organ-

pipewith one glass side,ab,as Shown in Figure 50.

An organ-

pipe may be made fromastraight lampch imney, by filingaholeat the lip, l,as Shown inFigure 49.

Fig . 49.

But great care is necessary to get it tightand not

break the chimney.

Obs. Blowinat the mouthpiece,and observe the

effect.


Drawapiece of rubber tubing from 16 to 24 inches

long over the mouthpiece.

Cut outapiece of writing paperalittle smaller


than the interior ofacross section of the organ-

pipe,and suspend it byathread .

Scatteralittle fine sand upon the paper,and, Holding the pipe verticallywith the open end upward, sothat you can see through the glass side, sound the

organ -

pipe by blowing through the rubber tube.

Slowly lower the sanded paper into the sounding

pipe,and carefullywatch the sand.

Obs. What do you observe ?

I nf. Infer the cause.

As theair is forced into the organ-

pipe, it strikes the lip ‘ (l, Figureand thus obstructed, it issues from the opening in rapid puffs.

The pulsations, thus produced ,are transmitted to the column ofairwithin the pipe,and cause it to Vibrate.



1 . SOURCES.

Name some bodieswhich originateCall such bodies luminous bodies.

Derive luminous.

Mention some bodieswh ich do not orlglnate light.

Call such bodies non-luminous bodies.

Derive non-luminous.

Callabodywh ich receives light from other bodies

1nd reflects itan illuminated body.

Derive the term .

1 . All light comes originally from what kind of

bodies ?

2. Name the natural sources of light.

3 . Name the chiefartificial sources of light.

The profitable study of light requiresaparts lumiéreandarrangements for darkening the room.

Thewindows maybe darkened bywide curtains of dark cambric,pinned close over thewindow-frames, or byshutters made bytackingstrong opaque paper overwooden framesmade to fit thewindow-frames.

A porte lumiére maybe bought forabout or one suitable forthese experimentsmaybe madeatan expense ofabout

To MAKE A PORTE LUM IERE .

Getapiece of pine board 9 incheswide,andas longas thewidth of

awindowon the south side of the school-room .

On one side of th is board mark outacircle 6 inches in diameter,with its centre ! inchabove the central point of the board .

Sawit outwithacompass-sawasmarked .

LIGHT. 127


If necessary, even the edge of this circular piece so that itwill turnasawheel in the hole.

In the centre Of thiswheel bore or cutaround hole 2 inches indiameter.

From 5 inch board cutaring (R, Figure 52) 7 inches in diameteron the outsideand 4 inches inside.

With 11 inchwire nails fasten th is ring to one side of thewheel, sothat its rimwillproject beyond the rim of thewheel 5 inchall round .

Cut outapiece of pine board 4 x 8 inches (M, Figure

To one side of this fastenapiece of looking-

glass, 39x 79inches,by small screws, placed so their headswill lap over the edge of the

looking-

glassW ithasuitable h ingeand rather long screws hang th ismirror to

thewheel in the position shown in Figure 52, so that the mirror maybe raisedagainst the wheel.In one edge of the mirror, 3 1 inches from thewheel, insertasmall

screw(S ) , letting the head project.Raise the mirroragainst the wheel,and withabradawl makea

hole (H ) through the wheel opposite the screwin the edge of the

mirror.

To the screwfasten one end ofastringabout 18 inches long,andpass the other end th rough theawl hole.

Upon the ring,alittle belowandat the right of theawl hole, bymeans of screws fastenasmall cleat (c) to h itch the string to. Thusthemirror maybe heldatanyangle desired .

Of hard wood make two buttons (B , B )about 11 x gx 1 inch ,and fasten each withascrewto thewheel,as shown in the figure.

Turn these buttons so that theywill not project beyond the rim of

thewheel, place thewheel in the board,and fasten it byturning thebuttons.

Place the porte lumiére under the lower sash ofawindowon the

sunny side of the room,andadjust it— by turning the wheeland

increasing or diminishing theangle of the mirror so that itwillthrowthe light squarelyand horizontally into the room .

For experimentswith small lensesasmaller opening for theadmission of light maybe needed A hole of the right size maybe cut inapiece of cardboardand the cardboard tacked or pinned over the

hole in thewheel.Derive porte lumiére.



b. RAY ; c. BEAM .


Strike together two erasers containing crayon dustalong the path of light.

Obs. 1 . Observe in what kind of lines the light

passes.

Callasingle line of lightaray.

Derive the term.

1 . Are there manyor fewrays of light thrown intothe room by the porte lumiere

?

Obs. 2. Howdo these rays compare in direction ?Callacollection of parallel raysabeam of light.

(I. PENCIL OF LIGHT.


Placeadouble convex lens (see page 13 9) in the

beam of light,and render the path of rays beyondthe lens visible by crayon dust.

Obs. Observe the relative direction of the rays beyond the lens.

Callacollection of rays converging to the samepoint or diverging from the same pointapencil ofThe first is calledaconverging pencil.The second is calledadiverging pencil.Derive pencil, convergingand diverging.

LIGHT. 3 1

c. IMAGE BY SMALL APERTURE


Boreaholeabout halfan inch in diameter in one

end ofasoap-box without cracks,and cover the hole

withapiece of tinfoil.

Prickahole in the tinfoilwithapin .

Invert the box overalighted candle inadarkenedroom,and holdasheet ofwhite paperasascreen before the hole in the tinfoil.

Obs. 1 . Observewhat forms on the screen .

I nf. 1 . See ifyou can think outand showby diagram howthis is formed .

Obs. 2. Bringing the screen near the box,andremoving it gradually, observe the effect upon the

image.

I nf. 2. See if you can explain the effect by diagram.

EXPERIMENT 1 5 5 (At sch 001. )

Throughahole from to g ofan inch in diameteradmit light fromwithout intoadarkened room,andhavealarge screen or lightwall on the side of the

room opposite the hole.

Obs. Observe the result.

j: SHADOW , UMBRA, AND PENUMBRA.

EXPERIMENT 1 5 6 . (At h ome. )

Beforealamp flame inadarkened room holdanopaque body smaller than the flame.

Holdawhite screen (paper) just beyond the opaquebody,and graduallymove it fartheraway.


Obs. Observe theappearance on the screen .

Inf. See if you can explain the appearance by

diagram .

Call the space fromwh ich light is shut Off byanopaque bodyashadow.

Call the space fromwh ichall the light is shut Offthe umbra.Call the space fromwh ichapart only is shut Off

the penumbra.Derive these terms.

g. ECLIPSE OF THE MOON.

Is the moonaluminous oran illuminated body?Where does its light come from 9

Is the earth transparent or opaqueWhat must there be on the side of the earthaway

from the sun ?

Is the earth larger or smaller than the sun

What must be the form of the earth’s umbra?What must be the form of the earth’s penumbra?Explain howan eclipse of the moon is produced .

It. ECLIPSE OF THE SUN.

Describe the umbraand penumbraof the moon .

Explain howan eclipse of the sun is produced .

i. VELOCITY OF LIGHT.

It has been found that ligh t passesacross the

earth’s orbit in 16 minutes 3 6 seconds.



DIFFUSED LIG HT .


Obs. Placeapiece of rough paper in the path of

the rays,and see if the light is reflected regularly.

Call light thus scattered byarough surface diflnsedlight.

IMAGE OF A POINT BY A PLANE MIRROR.

EXPERI M ENT 1 59. (At h ome.)

Hold the point ofyour pencil in front ofaplanemirror.

Obs. Observeand describe the location of the

image of the point,as seen fromany position .

Is the image in front of the mirror, or behind itHowfar ?Wherewith reference toaline perpendicular to the

mirrorand passing through the point of the pencil?IMAGE OF AN OB JECT BY A PLANE M IRROR

EXPERIM ENT 1 60. (At h ome . )

Holdany Object beforeaplane mirror.

Obs. Observeand state the position of the imageof each point of the Object.

When you look inamirror, the Image ofyour righ teye formswhich eye of the image ofyour face ?

ImAG Es BY Two PARALLEL PLANE MIRRORS.


Cut outapiece of board in the form ofaquadrantwitha. radius of 10 inches.

LIGHT . 1 3 5

Along one of the sides saw two parallel scaths(aand b in Figure 53 ) i ofan inch deepand 4 inchesapart ; and three other scaths (c, d,and e in the

figure),makingangles of 3 0, 60,and 90 degrees re

spectively with the scatha.In the parallel scaths place two pieces of looking

glass, 2 by 6 inches, facing each other.

Fig . 53 .

Obs. Placeapiece of crayon between these mirrors,and see if you can see more than one image of it.

Howmany ?Whereare they?

IMAGES BY Two PLANE MIRRORS Ar AN ANGLE.

EXPER IM ENT 1 6 2. (At sch ool.)

Obs. On the same boardarrange the mirrorsatangles of 3 0, 60,and 90 degrees,and find howmanyimages can be seen from one positionwith the mirrorsat each Of theseangles.

13 6 ELEMENTARY LESSONS IN PHSYICS.

CONCAVE MIRROR, PRINCIPAL Focus, FOCAL DISTANCE,CENTRE OF CURVATURE.

EXPERIM ENT 16 3 . (At sch ool.)

Placeaconcave mirror in the path ofabeam of

light inadarkened room, so that the lightwill strikeperpendicularlyat the centre of the mirror.

Obs. Render the path of the reflected light visible

by crayon dust, and describe the direction of the

rays.

Drawadiagram showing howthe ligh t is reflected.

Call the point through whichall the reflected rayspass the principalfocus of the mirror.

Derive focus.

Call its distance from the mirror the focal distanceof the mirror.

Call the point directly in front of the mirror twiceas farawayas the principal focus the centre of curvature of the mirror.

Inf. Infer why it is so called .

IMAGE BY A CONCAVE MIRROR.


Inadarkened room placealighted candleat considerable distance beyond the centre of curvatureandalittle to the right of it.

Holdapiece ofwhite paperasascreen just to theleft of the principal focus,and moving it slowlyawayfrom the mirror, see if the image of the candle flame

“

4 formed on it.


1 38 ELEMENTARY LESSONS IN PHYSICS .

Holdalong pencil, or straight stick, parallelwiththe beamabove the water, so that the under side of

the pencilwill just touch the beamalong the upper

side,and let the lower end of the pencil extend downward to the bottom of thewater.

Obs. Do the rays continue parallelwith the pencilafter entering the water?Call the change in direction refraction.

Derive the term.


Obs. Throwthe light perpendicularly into the

water,and see if there isany refraction .

DIRECTION OF THE CHANGE.

1 . Wh ich is the denser medium,air orwater ?Think ofaperpendicular to the surface of the

waterat the pointwhere the ligh t enters thewater.

2. Is the light bent toward this perpendicular, oraway from it,as it enters the water ?3 . Under what conditions have you found that

light is refracted,and in what directionarethe rays bent ?


Placeacent inabasin just near enough to one side

so that you cannot see it with the eye inacertainfixed position .

Without changing the position of the eye, carefully pour in on the farther side of the basin

,so

LIGHT. 139

as not to move the cent, enough water to nearlyfill the basin.

Fig . 55.

Obs. Can you see the cent now?Infer in what kind ofaline the light must

have passed from the cent to the eye.

Compare the direction in which the raysare benton leaving thewaterwith the direction in which theywere bent in Experiment 167 on entering thewater.

BY A DOUB LE- CoNVEx LENs.

A double-convex lens isacircular glass bodywithits sides curved out soas to make it thickest in the

centre.

A section of it is shown in Figure 56 .

Fig. 56.


A lens 3 or 4 inches in diameter is desirable forthese experiments, though a2-inch lens mightanswer.

OF PARALLEL RAYS, PRINCIPAL FOCUS, FOCAL DISTANCE .


Inadarkened room placeadouble-convex lens in

the path ofabeam Of light so that the light willstrike the lens perpendicularlyat its centre.

Render the path of the light visible.

Obs. Observeand state howit passesafter leavingthe lens.

Call the point through wh ichall the refracted lightpasses the principal focus of the lens.

I nf. What would you call its distance from the

lens?

IMAGE OF AN OBJECT.


Inadarkened room place the flame ofacandlejust beyond the principal focus ofadouble-convex

lens.

Obs. Find the image onwh ite paper on the other

side of the lens.

Describe the image. (Howfarawaycomparedwiththe object ? Howlarge ? Erect or inverted ?)


Increase the distance of the flame from the lens,

and tell howthe image changes.



Call th is combination of lensesacompound microscape.

REFRACT ING TELESCOPE.


Inadarkened room placeacandle flameat con

siderable distance fromalarge double-convex lens.

Just beyond the image formed by this lens, placeasmall lens.

Look through the small lens toward the flame

and describe the image seen.


Inalight room substituteany object for the candleflame,and Observeand describeas before.

Call th is combination of lensesarefracting telescop e.

Derive telescope.

Tell howthe refracting telescope differs from the

compound microscope.

REFRACT ION B Y A PRISM . SO LAR SPECTRUM .


Through asmall holeadmit ligh t from the sun

intoadark room,and haveascreen or wh ite wall

in the path Of the light. (Useaporte lumiere.)

Fig 57.

LIGHT. 143

What is formed on the screen ?

(See Experiment


Holdaglass prism, base upward, in the path of the

beam Of light.

Observe the change in the position, form,and color

of the image.

Infer the causes of these changes.

Call this image of the sun the solar spectrum.

Derive the term.

Name the colors of the spectrum, beginningat thetop.

Inf. 1 . Which raysare refracted most ?I nf. 2. Which raysare refracted least ?Writeatopical outline of the lessons on light,andaconnected composition upon mirrors or refraction.

PRACTICAL !UESTIONS.

1. When do objects extending upward from the

earth cast their f longest shadows in the sunlight upon

the ground ? Why?

2. When do they cast their shortest shadows ?3 . Upon what part of the earthare the shadowsalways long ?4 . When and where do such Objects cast no

Shadows5. What part of the moon shines?

6 . Does it Shine upon the earth when it is directlybetween the sunand the earth ?


7. Howmuch of it shines upon the earthatanytime ?

8. Do the stars Shine by their own ligh t, or by thesun

’s light ?

9. Distinguish betweenaplanetandafixed star.

10. Wh ich planets do you know11 . Does the earth shine With its own light12. Howcan the sun be seen before it has risen

above the horizon, orafter it has sunk belowthe

horizon

13 . When you look obliquely into clearwater,whydoes itappear shallower than it is ?14 . Inwh ich Of the preceding experiments did light

from the Object actually pass through the points

where the imageappeared ?Callan image so formedareal image.

15. In wh ich experiments did no light from the

object pass through the pointswhere the imageappeared ?Call suchan imageavirtual image.



Obs. 2. Was the Pall consumedI nf. 5. Why did n

’t the burning continue ?

Obs. 3 . Howdoes the part of theair left in the

jar compare in volume with that wh ich combined

with the P ?

Call the part of theairwh ich combined with the POxygen.

Derive the terms oxygenand phosphorus.

Call thatwh ich remains in the jar nitrogen. It is

an element, symbol N .

Derive the term.

Call the substance formed by the union of PandO p hosphorus pentoa'ide.

I nf. 6 . Is itan element oracompound ?Derive the name.

I nf. 7. Inferwhat proportion of theair is O .

I nf. 8. Inferwhat proportion of theair is N .

PREPARATION OF OXYGEN.


Powder inamortaraSpoonful of thoroughlydriedpotassium chlorate.

Mix with thisan equal quantity of manganesedioxide.

Fillalarge hard-

glass test tube one third full of

this mixture.

Fitastopper into the mouth of the test tube.

Perforate the stopperand fit into itaglass tubeabout 16 inches long, bentas shown in the figure.

CHEMISTRY OF AIR AND WATER. 147

Out ahole 1 inch in diameter in the bottom

and near the rim Ofatin plate (P, Figure 58) 5 or 6

inches in diameter.

Cutanother hole g. Ofan inch in diameter just belowthe hem in the rim of the plateandabove thehole in the bottom.

Fig . 58.

Invert this plate inapan,and pour into the panenough water to fill italittleabove the bottom of the

Inverted plate.

Fill four horse- radish bottleswith water,and, covering the mouths of thesewith pieces ofwindowglass,invert them,

filled with water, upon the bottom of

the plate in the pan, placing one Of them over the

hole in the bottom of the plate,and removing the

pieces ofwindowglass.

Support the test tube so that the end Of the glasstube will reach beneath the surface of thewater inthe pan .


Carefully heat the test tubewith the gas oralcohollamp flame, moving the flame soas to heat the partcontaining the mixture evenly throughout.

AS soonas bubbles begin to escape rapidly from the

tube, insert the end Of the tube through the hole in

the rim Of the inverted plate.

When one bottle is filledwith gas, promptly close

the mouth of it by slippingapiece Of windowglassunder it, remove th is bottle,and slipanother over thehole in the pan .

In thiswayfillall the bottleswith the gas.

While the bottlesare being filled, it maybe neces

sary to dip outalittlewater, from the pan, to prevent

thewater from getting too h ighand floating up the

bottles of gas.

Take the delivery tube from the water before re

moving the flame from the test tube. (Why?)

PROPERTIES OF OXYGEN.


Lightasplinter Of pinewood,andwhen it gets toburning, blowout the flameand thrust the glowingcoal intoajar Of oxygen ,

keeping the jar closed .



Wind one end Ofapiece of wire 10 inches longaboutasmall piece of charcoal,ignite the charcoal

,and thrust it into the second jar of oxygen .



Ignite the sulphur on the end of the wire,andinsert it inajar Of oxygen .


Inf. 1 . What do these experiments Showabout theaffinity of oxygen for other elements ?

A compound of oxygen with another element is

calledan oxide.

Inf. 2. What different oxides have been formed in

these experiments ?

Writeaconnected description of oxygen,

parationand properties.

The rapid union of oxygen withanother element

accompanied bylightand heat is called combustion .

COMBUSTION, COMPOSITION OF WATER.

A candle is composed chiefly of carbonand hydrogen .


Lightacandle, and holdacold lamp chimneyover it.

Obs. What collects on the chimney?

I nf. 1 . What is one substance produced in thc

burning of the candle ?Inf. 2. What is probably one of the elements of

which it is composed ? (Recall definition of com

bustion . )Let us see if we can learn what the other part

ofwater is.



Fillahorse-radish bottle with water,and, holdingaglass plate over itsmouth , invert it,and place it inapan containingalittlewater.

Wrap apiece of sodiumas largeasapeainapaper,and, holding itwith forceps, place it quicklyunder the jar without raising the mouth of the jarout of the water.

Obs. 1 . Observe what happens.

Cover the mouth Of the jar,and place it uprightupon the table.

Light one end ofasplinter of pine wood 1 footlong or more, slip the coveraside, and thrust the

burning end of the splinter quickly into the lowerpart of the bottle.

Obs. 2. Observewhat happens to the burning stick,and to the gas in the bottle.


Obs. 3 . Notice what forms on the inside of the

bottle.

Inf. I . Thiswaterwas formed in what process?Inf. 2. Then itwas formed fromwhat substances ?Inf. 3 . From what substance do you think the gas

came ? Why?1 . Describe the gas.

!Howdoes it differ from 0 ? (See Obs.

It is hydrogen (H).Derive the name. (See oxygen.)

Inf. 4 . What is water composed of?

Obs. 4 . Whenalamp or gas is lightedandacoldchimneyis placed over the flame,what gathers on thechimneyI nf. 5 . Where do the elementswhich form it come

from ?

Let us see ifwe can learn whetherany other sub

stance than water is formed in the burning of the

candle.


Fitavaseline bottle, or otherwide mouthed bottle,

withagood stopper.

Into th is stopper fitair-tigh t two glass tubes, oneabout 10 inches long, just reaching through the stop

per fromabove,and the other long enough to reachnearly to the bottom of the bottleand projectan inchabove the top of the stopper.

Bymeans ofapiece Of rubber tubing 6 or 8 inches

long, connect the top of th is last tubewith the tube

ofasmall tin tunnel



Obs. 1 . Repeat the two parts of the last experi

ment justas with water,and noticeany effect upon

the lime-water.

Obs. 2. Let the bottle stand forashort time,oh

serveany change in the liquid,and notice carefullythe bottom of the bottle.

I nf. I . Inferwhat the coloring of the liquid wasdue to.

Inf. 2. Infer howmany substances must havecombined to form this newsubstance.

I nf. 3 . Inferwhere theymust have come from .

Inf. 4 . Could that wh ich came from the burning

candle have been the water ?Why not ?

Inf. 5. What state of matterwas it ?Wewill prepare some of it inanotherway.

EXPERI MENT 190. (At sch ool. )

Prepareahorse-radish bottle of O,and, keeping thejar closedas much as possible, repeat Experiment183 .

Inf. 1 . Is the substance left in the jar 0 ? Howdo you know?Inf. 2. What was it formed from ?Inf. 3 . Infer what element combined with the

oxygen .

The gas formed is called carbon dioxide.EXPERI MENT 19 1 . (At sch ool. )

Obs. Thrustaligh ted match into the jar in which‘h e charcoalwas burned ,and Observe the effect ,



Obs. Loweralighted candle into the jar,and ob

serve the effect.

In these experiments keep the jar closedasmuchaspossible.


Obs. Pouralittle lime-water into the jar, shakeit,and observe the effect.

Inf. 1 . Infer what the substancewas which camefrom the burning candleandacted upon the lime

water.

Inf. 2. What two substancesare formed in the

burning ofacandle ?Supplementary experiments may be taken to see if

carbon dioxide is formed in the burning of kerosene,illuminating gas,and wood.

CHANGES IN AIR IN THE HUMAN BODY.


Obs. Breathe uponacool piece of glass or chinaand observe the effect.

Inf. Infer one substance given out in breath ing .


Obs. Refillwith lime-water the bottle used in Ex

periments 188- 9, remove the short glass tube from the

stopper, push the other tube through the stopper farenough to reach nearly to the bottom of the bottle,

breathe out through the glass tube,and observe the

effect upon the lime-water.


I nf. 1 . Inferanother substance given out in breathmg .

1 . Compare the substances given out in breathingwith those formed in the burning of the

candle.

2. What substance is taken out of theair incombustion

Inf . 2. Inferwhat is taken from theair in theactof breathing .

Inf. 3 . What objectionsare there to breathing thesameair overand over ?

I nf. 4 . Doesalighted lamp or gas jet improve, orinjure theair ofaroom for breathing ?Three men had occupied the closed cabin ofaboat

foran hour when itwas found thatamatch wouldnot burn in the cabin .

Inf. 5. Infer why.

Inf. 6 . Was suchair fit to breathe ?Inf. 7. What must be done with theair ofan

occupied room to keep it fit for breath ing ?Describe fully in writing,with drawings ofappara

tus, experiments Showing changes in the burning

candleand in the human body.

Isyour school-house properly ventilated ?

If 80, -writeadescription of the system,with diagrams.

If not, think outagood plan for ventilating it,andpresent it in writing,with diagrams.


I N D E X.

NUMB ERS REFER TO PAGE .

AB SORPTION OP GASES, 29.

Action, 3 6 .

Adhesion, 19.

Aeriform matter, 11 .

Air-chamber, 69.

Angle of incidence, 13 3 .

Angle of reflection, 13 3 .

Artesianwells, 57.

Atom, 6 .

Attraction, capillary, 29; molar,molecular, 19, 26 .

Axle,74 .

B ALANCED BAR, 109.

Barometer, 63 .

Beam of light, 13 0.

Boiling , 91.

C APILLARY ATTRACTION, 29.

Carbon dioxide, 154 .

Centre of curvature, 13 6 .

Centre of gravity, 46 .

Centrifugal force, 18.

C hanges inair,In combustion, 150.

In the human body, 155.Chemicalaffinity, 16 .

Chemical change, 14 .

C hemical force, 16 .

C hlorine, 5 .

Clouds,94 .

C ohesion, 19.

Combustion, 150.

Components, 4 1.

Composition of forces, 3 9.

Compound, 6 .

Compound microscope, 14 1 .

Concave mirror, 13 6 .

Condensation of vapor, 93 .

Conduction, of electricity, 111 of heat,95 .

Conductor,ofelectn cxty, 1 12 ofheat,95.

Constant force, 3 0.

Convection of heat, 97.

Correlation of forces, 26 .

Crowbar, 74 .

Crystallization, 28.

Crystals, 28.

DEODORIzER,3 0.

Derivation, 2.

Dew, 93 .

Dewpoint, 94 .

D ifiused light, 13 4 .

Double convex lens, 13 9.

Draught, 99.

ECLIPSE or MOON, 13 2.

Eclipse of sun,13 2.

Effects of heat, 88; of Voltaic electricity, 114 .

Electro-magnet, 116 .

ElectrOSCOpeS , 108.

Element, 6 .

Energy, 3 9.

Equilibrium, 40, 46 .

Evaporation, 92.

Expansion, of gases, 90; of liquids, 88 ;of solids, 88.

160

FALLING Rooms, 49.

Filter, 29.

Filtrate, 29.

Fixed pulley, 78.

Floatingand sinking, 59.

Focaldistance,13 6 .

Foot-pound, 3 8.

INDEX.

Lever, 71.

Lifting pumps. 65.

Light, 20, 126 .

Lino of direction, 46 .

Liquefaction, 90.

Liquids, 8.

Load of lever, 72.

Force, 16 centrifugal, 18 ; chemical, Loudness of tones, 120.

16 constant, 3 0; impulsive, 3 0 meas Luminous bodies, 126 .

um of, 3 7 ; molar, 3 0 ; muscular, 16 ; Luminous efiects of electricitv 116

physical, 16 tendencyof, 3 1.

Force pumps, 68.

Frictional electricity, 21 107.

Frost, 94 .

Fulcrum, 71.

HAIL, 94 .

Heat, 20 ; conduction of, 95 ;of, 88 latent, 101 radiationsources of, 87.

Horse-

power, 3 9.

Hotwater heating, 98.

Hydrogen, 152.

ILLUMINATED B ODIES,126.

Image:Byconcave mirror, 13 6Bydouble convex lens, 140.

Byplane mirrors, 13 4 .

Bysmallaperture, 13 1 .

Impenetrability, 4 .

Impulsive force, 3 0.

Inclined plane, 82.

Induction of electricity, 113 .

Inertia, 3 4 .

Inference, 2.

Insulator, 112.

LATENT HEAT, 101 .Law,

Ofmagnets, 105.

Of electricalaction, 110.

Of reflection of light, 13 3 .

MAGNETIC DECLINATION, 106 .

Magnetic efiects of electricity, 116 .

Magnetic needle, 105.

Magnetism, 21, 103 .

Magnets, 103 .

Mass, 6.

Matter, 1 .

Measure ofatmospheric pressure, 64Measure of force, 3 7.

Medium,129.

Microscopes, 141 .

Mirrors, 13 4 .

Molecularattraction, 19, 26 .

Molecule, 5 , 7.

Momentum, 3 3 .

Movable pulley, 78.

Muscular force, 16.

NEGATIvE ELECTRICITY, 110.

Negative pole, 105 .

Neutral equilibrium, 47.

Nitrogen, 146 .

Non-luminous bodies, 126 .

O B SERVATION, 1 .

Odor, 7.

Opaque bodies, 129.

Organ pipe, 123 .

Oxide, 149.

Oxygen, 146 .

PENCI L O F LIGHT, 130.

Pendulum, 49.

Penumbra,13 2

Permanent magnet, 104 .

Phosphorus, 145 .


HINTS FOR MAKING APPARATUS.

ANalmost endless varietyof simpleapparatusmaybe madebyany one interested in the subject of physics, if hewill exercisealittle ingenuityand devoteasmall portion of h is timeasoccasion calls for newth ings. Work on th ings of this kind isarelief from ordinary school duties. The very simplest illus

trations of great facts make impressions far more valuable thandemonstrationswith complexand h ighlyfinishedapparatus furnished bythe stores. With bottles, glass tubing, rubber tubing,corks, rubber stoppers,and tin cans one can fit upavery interestingand useful laboratory.

In the first place one needs to practise drilling holes inbottles, lamp ch imneys, etc.,and cutting off bottles. Anyone

who uses fileswill giveawayworn out files,whichareas goodas newfor th iswork .

Nowlet us supposeweare going to drillahole in the side of

abottle. B reak offalittle of the end ofathree-cornered file,

soas to make sharp cornersat the end,and scratchaplace

where the hole is to be drilled ; then turn the file back .andforth , frequentlywetting the end inwater, or spirits of turpentine,and by careful

, patient work forabout five minutes weshall succeed in makingahole. When the hole is nearlyth rough , care must be taken not to have it break th rough

suddenlyand crack the glass. Several trials maybe necessaryat first to learn just howto do it successfully. I f the file be

comes dulled on the end, chip oflz'

small pieceswithahammer.

After the hole is drilled,wewish to fit inatube or spout.

Cut offapiece of rubber tubingabout halfan inch long,wet it,

HINTS FOR MAKING APPARATUS . 163

and insert it into the hole. Then makeaspout of glass tubing,and insert it into the piece of rubberalready in the hole.

This makesanair-tightand water-tigh tarrangement, shownin figurea. A bottle may have several holes for differentexperiments,and those not in use maybe plugged by insertingaglass plug instead of the glass spout. By slipping over the

end ofaspoutashort piece of rubber tubing pluggedat oneend,as shown in b, it may be closed till the time comes to havethewater run .

To cut offabottle, scratcharound itwith the sharp edge ofafile

,and followthe scratch withasmall jet of gas flame fromaglass nozzle, connected with the gas pipe byarubber tube.

The bottle will then break squarely. Where gas cannot behad,alittle filingandapplying the sharp edge ofahot ironworks fairly, though it is not so sureas the gas flame.


That water seeks its level may be shown by bottles of dif

ferent shapesand sizeswith holes bored in the bottoms, or the

bottoms broken off,to let theair out. With perforated corksand glass tubing, connect them W ithahole bored lengthwise

throughashort strip of boardand corkedat each end,as shown

in c. A still simplerarrangement is to use only two bottles, orabottleandatin can (d) connected by rubber tubing.

The pressure of liquids maybe shownwithabottle like thatrepresented in 0. Push it down intoaglass jar ofwater,andsee thewater spout upward in the bottle. Plug up the hole in

the bottom,and put spouts into the side holes. Notice the

difference in the force of th e jets. Many other experiments

can be performed withabottle of th is kind.

B reak offagood-sized bottle,and runasiphon down throughthe cork,as in figuref. Th is makesagood Tantalus cup.

The diving bellmaybe illustrated bystickingasmall imageofaman on the insideofatumbler or gobletwith sealingwax (g) .The Cartesian diver maybe shown byfillingalittle vial fullenough ofwater so that itwill just float ; then carefullyput it,mouth downward, intoabottle ofwater (it). Push ing the stop

per of the bottle downwill compress theair enough to sink the

vial,and pulling the cork upwill cause it to riseagain .

The Hero fountain, the hydraulic press,and manypieces ofelectricalapparatusare easilymade,andwhen once made, formapermanent set ofapparatus, which encourages the pupil tooriginal investigationand independent thoughtandaction.



7. A substance is matter ofasingle kind.

The term substance is formed from the Latin sub,under

,and stare,atom ,standing ; i. e. , that wh ich stands

under (the external qualities) .

IMPENETRAB ILITY.

Inf. 3 . Onlyone body can occupythe same spaceat thesame time.

Theword impenetrabz’lity is formed from the Latin im,not,

penetrare, to put in ,able, capable of,and ity, the qualityof

i. e., the qualityof not beingable to be put in .

The following composition is offeredasasample ofwhatmaybe expected from pupils in thiswork .

THE IMPENETRAB ILITY OF MATTER.

Ifabottle be filledwith water,andalong pencil thrustinto it, some of thewaterwill run over. As the bottlewas

full ofwater, therewas no room for the pencil ;andwhen itwas put in , thewaterwas forced out.

Ifan inverted tumbler held evenly is lowered intowater,thewater does not rise much inside of the tumbler ; for the

DIVISIONS OF MATTER . 167

room in the tumbler is occupied by theair,and thewatercannot get in there unless theair gets out.

Whenanail is driven intoablock ofwood, it forces thefibres of woodaside, crowdingthem closer together,and makesroom for itself.

Whatever, like the pencil, theair,or the water, occup ies room

is matter. A thought,afeeling,orawish requires no space,and is not matter. A portion

of matter, like thewater in the pan , theair in the tumbler,orarubber eraser, isabody.

N0 two of these bodies could occupythe same spaceat thesame time. Th is is true ofall bodies. Thus matter is saidto be impenetrable ;and the propertyof matter bywh ich no

two bodies can occupythe same spaceat the same time iscalled impenetrabilz'ty.

II . DIVISIONS OF MATTER.

MOLECULE.

Molecule is formed from the Latin moles,ahuge shapelessquantity of matter,with the diminutive ending cule

,little

15. e. ,alittle quantityofmatter.

MASS .

llIass is formed from the Latin massa, thatwh ich stickstogether like dough ,alump.

1 . A pound of butter,an iron weight,agallon ofwater,apiece of board,apiece of coal,andarubber eraseraremasses ofmatter.


COMPOUND.

Obs. Sodium isasoft, silvery-looking metal, easily cut

withaknife.

Chlorine isagreenish -

yellowgaswithastrong suffocatingodor.

2. Compoundsare substanceswh ich have been found tobe composed of two or more different k inds of

matter combined in definite proportions.

The term compound is from the Latin ponere, to put,andthe prefix com,

together ; someth ing put together.

ELEMENT.

3 .

“ Such substances are those wh ich have never been

separated into different kinds of matter.

Element is from the Latin elementum,one of the first

principles of things.

4 . A molecule of salt contains the elements sodiumandchlorine.

I nf. There must be less of the sodium than of the saltinamolecule.

ATOM .

5 . Anatom is the smallest particle of matterwhich canexist combined with other particles. It isalwaysan element.

Atom is formed from the Greeka, not,and TOpO'

S‘

, to be

out ; i. e.,not to be cut.

6 . We have considered masses, molecules,andatoms.

7. I have seen masses ofmatter.

I nf. 2. The other divisions must exist. There must be

asmallest quantitv of matter wh ich can exist by itself,and asmallest quantity wh ich can exist combined withother matter.



2. SOLIDS .

5. The particles of wood,iron ,and glass cling together,

but do not move freelyamong themselves.

EXPERIMENT 6 .

Obs. The outer end of the sealing wax is slowly bentdownward .

I nf. 1 . The molecules of wax have been slowly movedamong themselves.

Inf. 2. Such substancesaswood, iron ,andwaxare calledsolids.

The particles of these substances tend to cling together,and do not move freelyamong themselves.

Solidsare substances whose particles tend to cling to

gether,and do not move freelyamong themselves.

Solid is formed from the Latin solidus, firm.

3 . AERIFORM MATTER.

EXPERIMENT 7 .

Obs. 1 . The lower half of one bottle is filled with water ;the upper halfand the other bottleare filled withair.

Obs. 2. Some of thewater goes through the tube into theother bottle.

Inf. 1 . Some of theairwent from the first bottle into the

lungs, leaving lessair for the space than therewas in th eupper half of the other bottle. The more crowded or dense

air Spread out,and drove some of the water through th e

tube.

Inf. 2. Molecules ofair tend to separate.

1 . Its particles tend to separate.

2. Its particlesmove freelyamong themselves.

CHANGES IN MATTER. 171

3 . Its particles move freelyamong themselves,and tendto separate.

4 . Aeriform matter is matterwhose particlesmove freelyamong themselves,and tend to separate.

Aeriform is from the Latinaer,air,and forma, shape,nature, or k ind .

5. Chlorine isaeriform matter.

6 . Liquidsandaeriform matterare calledfluids.GAS AND VAPOR

EXPER IM ENT 8.

Obs. Aeriform matter is formedand goes into theair.I nf. 1 . It is formed from thewater.

Infi 2. Whenwet clothing dries, thewater goes into theair.

1 . We cannot see thiswater in theair.

2. Water is ordinarilyaliquid.

3 . Th is invisiblewater in theair isaeriform matter.

4 . Vapor isaeriform matter ofakind wh ich is more

commonlyfound in the liquid or solid form ; whileair does not occur in the liquid or solid state.

5 . Chlorine, illuminating gas, and “ laughing gasaregases.

IV. CHANGES IN MATTER

1 . CHEMICAL CHANGE.

EXPERIMENT 9.

NOTE . If the teacherwishes to showall the changeswhich occur

in th is experiment, let him fit the test tubewithaperforated stopper

intowhichashort piece of glass tubing has been fitted,and insert thestopper,afteradding theacid . Itwill then be seen that the first gas


in the test tube is ofareddish -brown color ; butafterall theair hasescaped from the test tube, the gaswh ich is being formed is colorless,and becomes reddish -brown onlywhen it mingleswithair. Hence it

must combinewith theair, orwith someth ing in theair,and formanewgas. The noteswh ich followcorrespond with the directionsasgiven in the manual.Obs. Little bubbles form in the liquid,areddish-brown

gas fills the test tubeand escapes,and the liquid becomesblue.

Inf. 1 . Neither copper nor nitricacid would turn the

liquid blue.

A blue substance must have been formed, wh ich is dissolved ih the liquid .

I nf. 2. Two newsubstancesare being formed.

1 . Each differs from copper in color,and the gas isadifferent state of matter.

2. Theydiffer from nitricacid in the same particulars.

I nf. 3 . Theymust have been formed from the copperandnitricacid ,and theair.

3 . Theywere formedwith in the test tube,and therewasnothing else there.

I nf . 4 . The molecules of the newsubstances must bedifferent from the molecules of copperand nitric acid ;otherwiseacollection of molecules—amass—would not

be different.

I nf. 5 . Theatoms must be the same ; they cannot bechanged ;and no others were present.Chemical is probablyformed from the Greek xvuo

'

s‘

,juice,

with the suffixal, relating to. C hemistry seems to havedealtat first with the extraction of juices from plants.

I nf. 6 . The copperand nitricacid were not changed intonothing.

I nf. 7 . Theiratoms combined in newways to form the

ubstances.



the state of being. Hence it would mean the state of

having boundaries together. It is used to mean the forcewhich holds them together.

1 . Itacts betweenatoms.

2. Physical forcesact between molecules or masses.

3 . DIFFERENT FORCES .

a. MUSCULAR FORCE.

EXPERIM ENT no.

Inf. 1 . Force produces the change.

1 . The forcewas exerted bymuscles.

I nf. 2. A force so exerted maybe called muscular force.

2. Bending the finger, raising the eyelid, turning the head,and everymovement ofany organ ofananimal isthe effect of muscular force.

b GRAVITATION.

EXPER IMENT l l .

Obs. l . The blocks begin to moveabout.068. 2. The ch ips have come together, mostlyaround the

outside of the pail.Inf. Some force must have drawn them togetherand to

the sides of the pail.When two boatsare near each other, theytend to come

in contact. A vessel nearawharf seems to be drawntowards it.

EXPERIM ENT 1 2.

Obs. The brick falls to the ground.

Inf. Some force must drawit downward.

EXPER I MENT 1 3 .

Obs. 1 . It presses downward .

Inf. 1 . Some force must drawit downward.

FORCE. 175

1 . This forceacts between masses ofmatter.

2. It drewthe bodies towards each other.

3 . Gravitation is the forcewh ich draws masses of mattertowards each other.

G ravitation comes from the Latin yravis, heavy,with thesulfixesat(e), to make,and ion , thatwh ich ; i . e. , thatwhichmakes heavy.

GRAVITY.

4 . In the last two experiments gravitationacted betweenthe earthand the brick .

5 . Th is forceacts between the earth ,and bodies on or

near its surface.

G ravity is derived from the Latin gravis, heavy,with thesuffix ity, the state or qualityof being .

6 . The name gravitationalsoapplies to th is force.

7. G raviyyis the more definite name, since itapplies onlytoattraction between the earth and other bodies

near it.

I nf. 2. A forcewh ich drawsmatter together maybe calledattraction .

Molar is derived from the Latin moles,mass, with the

suffixar, belonging to ; belonging to masses.

Attraction is from the Latin trahere, tractum, to draw,with the prefixat (forad) , to or towards,and the suffix

ion,thatwh ich (in this case) ; thatwh ich draws together.

Obs. 2. The string pulls on the fingers.

Obs. 3 . The chestnut flies off inastraight line.

Inf. 3 . A body moving in the circumference ofacircletends to move inastraight line.

8. Mud flying off from carriagewheels, shotand stones

thrown fromasling, showth is tendency.

9. It isatendencyof bodies moving in the circumference

ofacircle to move off inastraight line.


Centrifugal comes from the Latin centrum, centre,and

fuyere, to flee ; fleeing from the centre.

I nf. 4 . Gravitation prevents the planets from movingaway from the sun .

0. COHESION.

Inf. 5. It might be called molecularattraction .

10. Itacts between molecules of the same kind .

Call the force 'wh ich holds molecules of the same kindtogether cohesion .

Cohesion is derived from the Latin hcerere, to stick ,the prefix co (for con ) , together,and the suffix ion

, thatwh ich ; i. e.

, that wh ich causes to stick together.

d. ADHESION.

EXPERIM ENT I 4 .

Obs. The pencil iswet.

I nf. Some force causes thewater to stick to the pencil.

EXPERIMENT I 5 .

Obs. Some of the lead remains on the paper.

Inf. Some force causes the lead to stick to the paper.

1 . The molecules of leadand paperare unlike.

Adhesion is derived from'

same rootas cohesion. Ad

means to.

2. Adhesion holds molecules of different substancestogether, and cohesion holds molecules of th e

same substance together.

3 . Theyboth hold molecules together.

e. HEAT.

EXPER I MENT re.

Obs. Thewax melts.



I nf. 1 . A chemical change is taking place.

Obs. 3 . Theaction is the sameaswhen the ends of the

plates were in contact.Obs. 4 . The needlewas notaffected .

Obs. 5. The direction of the needle is changed .

I nf. 2. Itwas developed by chemicalaction .

Voltaic is formed from Volta, the name ofan investigatorin this field,and ic, pertaining to.

1 . We have noticed muscular force, gravitation , gravity,cohesion ,adhesion , heat, light, magnetism, frictionalelectricity,and Voltaic electricity.

2. Muscular ferce, gravitation, magnetism,frictional elec

tricity,and Voltaic electricityact upon masses of

matter.

I nf. 3 . These may be called molar forces.

3 . Cohesion ,adhesion ,and heatact upon molecules.

I nf. 4 . These maybe called molecular forces.

4. Gravityand gravitation (magnetismand frictional electricitysometimes) tend to bring bodies together.

5 . Adhesionand cohesion hold molecules together.

6 . These have been called molecularattraction .

4 . CORRELATION OF FORCES .

EXPERIMENT 21 .

Obs. At first the cent felt cool, butafter the rubbing it

feltwarm.

Inf. The heatwas produced by the rubbing.

1 . Muscular forcewasapplied in th is experiment.

2. Heatwas developed by it.

3 . Heat is developed by friction on th eaxlesand brakesof carsand carriages,and in the use of gimlets,

bits, knives, planes,and other tools.

FORCE. 179

EXPERIMENT 22.

Obs. 1 . It consists ofwood,withabout one fourth ofan

inch of the lower end coated with brimstone,and the verv

end tipped withapreparation containing phosphorus.

Obs. 2. The phosphorus begins to burn W ith apaleyellowish flame ; then the sulphur burns withapale blueflame,and finally the wood

,withayellowflame.

Obs. 3 . The flame feels hot.I nf. 1 . Heatwas developed by the rubbing.

1 . The burning immediately followed the rubbing .

I nf. 2. C hemicalaffinitymust have caused the newcom

binations ofmatter.

The heataided theaction of th is force.

I nf. 4 . Heat is developed bytheaction of chemicalaffinity.

This fact is inferred, because heatwas manifestas soonaschemicalaflinityacted .

I nf. 5 . By theaction of th is heat chemicalaffinity is

made toact further in the burning of the sulphur andthe wood .

Inf. 6 . Theamount of heat developed in this chemicalaction is much greater than that used in starting the

action .

2. In Experiment 22, muscular force produced some

beat ; th is ‘

started theaction of chemicalaffinityin the burning of the phosphorus, bywh ich suffi

cient heat was produced to continue theaction of

chemicalaflinity in burning the sulphurand then

the wood ;and th isaction produced more heat.

Inf. 7. In the use ofalocomotive to moveatrain of

cars, chemicalaffinityacts first in the fire-box.

I nf. 8. By th isaction heat is produced .

I nf. 9. The heat changes the water in the boiler into

steam, which by its pressure moves the train .


Mechanical is from the G reekanxavq , machine,andal,pertaining to ; i. e. , pertaining toamachine.

3 . The heat produced in the fire is converted into a.mechanical force.

4. Lightning is theaction of electricity.

5 . Buildingsare often set on fire by being struck bylightn ing .

I nf. 10. Heat must have been developed in order to

produce th is effect.

6 . In this case electricity produced heat,heat caused

chemicalaffinity toact, th isaction produced heat,and the heat produced light.I nf . 11 . In producing electric ligh t for towns, chemicalaction, heat, mechanical force, electricity, heat,andlightact in that order.

Correlation is from the Latin car,with , or together, re,

again , ferre, latum,to bring,and ion ,

theact of.

5 . MOLECULAR ATTRACTION.

Cohesion and adhesion are two forms of molecularattraction .

Cohesion is the forcewh ich holds molecules of the samesubstance together,andadhesion is the force that holdsmolecules of different substances together.

SOLUTION AND CRYSTALLIZATION.

EXPER IM ENT 23 .

Obs. Solid pieces ofalum form on the string,and on the

inside of the tumbler.

1 . Thealumwas solid .

2. Thewaterwas liquid .

3 . Thealum became liquid in the hotwater.

Solution is from the Latin solvere, solutum, to loosen, dis


182 ELEMENTARY LESSONS IN PHYS ICS .

Oiland mercuryare lower in the tubes than outside ;and the smaller the tubes the more the liquids insidearedepressed.

Inf. There isanattraction between the glass of the tubesand the particles ofwaterandalcohol ;and the smaller th etube, the nearer the liquids will be to the glass,and the

more theywill beaffected by it ; wh ile the particles ofmercuryand glass,and of oiland glass repel each other

,and

the opposite effect is produced .

1 . Theattraction manifest in Experiments 24and 25 isbetween molecules ofasolidand those ofaliquid.

2. It causes the liquid to rise upon the surface of th e

solid.

Capillaryattraction isaform ofadhesion betweenaliquidandasolid, inwhich the liquid rises on the surface of the

solid .

Cap illaryis from the Latin cap illus, hair,andary, relatingto, or like ; i. e. ,

hair-like.

Attraction is from the Latinad , to, trahere, tractum, to

draw,and ion ; i. e. , theact of drawing to or together.

AB SORPTION OF GASES.

EXPERIM ENTas.

FILTER.

Obs. 1 . Ammoniahasastrong, pungent odor.

Obs. 2. The liquid works through the paper,and dropsinto the bottle.

Obs. 3 . The filtrate does not smell stronglyofammonia,but the charcoal doesInf. 1 . Theammoniagas has gone from the liquid into

the charcoal.Inf. 2. The charcoal takes the gases out of the liquids.

I nf. 3 . Adhesionacts here.

FORCE . 183

Deodorizer is formed from the Latin de,away, odor, odorize

,make or give, er

,that wh ich ; i. e.

, that which makes(takes) away odor.

I nf . 4 . A drop of oil spreads over paper because there isanattraction between the molecules of the oiland those of

the paper.

1 . The oil ofalamp burnsat the top of thewick .

I nf. 5 . It is drawn up by theattraction between the mole

cules of the oiland those of thewick .

6 . MOLAR FORCE.

a. IMPULSIVE AND CONSTANT.

1 . The forcewith wh ichabat strikesaballacts only foran instant, wh ile the force wh ich draws the balldownwardacts continuously.

An impulsive force is onewh ichacts onlyforan instant.

Impulsive is from the Latin in,against, p ellere, pulsus, tostrike,and ive, having the qualityof, or tending ; i . e.

,tending

to strikeagainst. A striking forceacts onlyforan instant.A constant force is onewh ichacts continuously.

Constant is from the Latin constare,constans

,standing

firm ; i . e. , unchanging .

2. The pressure of steam inaboiler isaconstant force.

3 . Theattraction of two bodies for each other isaconstant force.

4. Forceapplied byablowisan impulsive force.

b. TENDENCY OF FORCE.

EXPER IM ENT 27 .

Obs. The ballmoves upward moreand more slowly, stopsand moves downward , slowlyat first, but gradually faster.

I nf. 1 . Muscular force of thearm produced the motion.


I nf . 2. Gravity caused the changes in the motion .

1 . Molar force does notalways cause motion , or changeof motion .

2. One maypress downward uponatable,and the tablewillnot move.

3 . Gravity draws the table down , but the table doesn’tmove.

I nf. 3 . The tendency of molar force is to produce motion ,

or change in motion .

0. VELOC ITY OF MOTION.

A train of cars goes thirtymilesan hour .

A man walks th ree milesan hour.

I nf. 1 . Call the rate ofmotion ofabody its velocity.

Velocity is from the Latin velox, swift,and ity, the qualityof i. e.

,the qualityof being swift.

3 . An hour isaunit of time.

4 . Eight miles isadistance.

5 . We stated the distancewh ich the train passed inaunitof time.

6 . The earth turns equal distances in successive hours.

7. Uniform velocity isarate of motionatwh ichabodypassesover equaldistances in successiveunitsoftime.

Uniform is from the Latin unus, one,and forma, form,

manner, kind ; i. e. of one kind .

8. Whenatrain is getting under way or coming toastop, it passes over different distances in successive

seconds.

9. Variable velocity isarate of motionatwh ichabodymoves overadifferent distance in each successive

unit of time.

Variable is from the Latin varius, of divers colors, different,andable,able to be.

Here the sense seems to be (continually) being different.



EXPERIMENT 29.

1 . There is two or three timesasmuch movement ofmatter inasecond in the second caseas in the first.

Inf. The momentum ofabodyalso depends upon the

weight of the moving body.

e. INERTIA.

Inf. 1 . A moving bodycould never change its velocity or

direction ofmotion unlessacted upon bysome force.

Inertiaof motion is the inability ofamoving body to

change its motion .

I nertiais from the Latin in , not,are,art orability,and ia,the qualityof i. e. , the quality of not havingability.

Inf . 2. Call the inabilityofabodyat rest to move inertiaof rest.

Inertiaof rest is the inability of bodiesat rest to move.

I nf. 3 . The man fell overboard, because the boat stopped

suddenly,and the man’s body could n’t stop of itself,and

he did n’t have time to stop it.

Inf. 4 . The body ofaperson onamoving car ismovingat the same rateas the car ;andwhen he steps upon the

ground the motion of his feet may stop suddenly,and hebe thrown forward.

I nf. 5 . He should face in the direction inwh ich the caris moving,and when he touches the ground takeafewsteps forward, until he can stop the motion of h is body.

I nf. 6 . A car started suddenly,and manyof the standingpassengerswere thrown backward .

Inf. 7. Their feet were suddenly carried forward,andtheir bodies were left beh ind .

Inf. 8. The inertiaof rest cannot be overcomeallat once.

I nf. 9. The inertiaof motion is too great to be overcomeallat once.

FORCE . 187

1 . There isaterrible wreck . The inertiaof motion is

immense,and cannot be overcomeallat once.

2. In drivinganail, the force,as it isapplied to the

nail, is the inertiaof the hammer.

I nf. 10. By sudden blows the carpet is forcedaway,andthe dust is left behind, onaccount of its inertiaof rest.

f. RESISTANCE.

OF TH E AIR.

EXPERIM ENT 3 0.

Obs. More force is required for the second movement.

I nf . 1 . Theair h inders themotion more in the second case.

Resistance is thatwhich h indersmotion .

Resistance is from the Latin re,again (against) , sistere,to stand, and ance, theact of ; i. e.

,theact of standingagainst.

Inf. 2. It is really due to the inertiaOf theair.

OF INERTIA .

Inf. 3 . The greater part of the resistance in startingatrain of cars is due to inertia.Inf. 4 . Theamount of th is resistance depends upon the

weight of the cars.

OF FRICT ION.

EXPER IMENT 3 1 .

Obs. Force is required to continue the motion,after the

inertiaof rest has been overcome

Inf. The motion is hindered bythe rubbing of the bookupon the carpet.

OF MUSCULAR FORCE.

EXPERIMENTas.

Obs. More force is required than in ExperimentInf. Th is difference is due to the resistance of

forceapplied by the fingers.


OF GRAVITY.

EXPERI MENT 3 3 .

Inf. 1 . The resistance is due ch iefly to gravity.

I nf. 2. The surplus force wh ich gravity does not resist

is used in overcoming the inertiaof rest,and producingmotion upward .

Inf. 3 . All of th is surpluswillbe used up in thisway.

Inf . 4 . The sum ofall the different forms of resistanceequals the force resisted .

I nf. 5 . The direction of the resistance is Opposite that ofthe moving force.

I nf. 6. Byaction Newton means moving force,and byreaction , the various forms of resistance.

g. MEASURE OF FORCE.

EXPER IM ENT 3 4 .

The facts observed under this experimentwill varywiththe bookand the spring .

The common unit used for the measure of gravity in th iscountry is thepound . The gram is used toaslight extent.

EXPER IM ENT 3 5 .

1 . The force thatwill hold up one pound is halfas greatas one thatwill support two pounds,and one fifth

as greatas one that will support five pounds.

h . WORK .

Inf. 1 . In drawingadouble runner up h ill, inertiaof rest,

friction , gravity,and resistance of theair must be overcome.

I nf. 2.a. The work of raisingapound one foot is one

fourth of the work of raising it four feet.6 . It is one tenth of that of raising it ten feet.

c. It is one fourth of that of raising two pounds two feet.



Resultant.1 . The two leadsact in the same line.

2. Theyact in the same direction .

Obs. The single forcewh ich will produce the same effect(balance the sand) is theweight ofath ree- inch lead.

A resultant of two or more forces isasingle forcewh ichwill produce the same effectas the two or more forcesactingtogether.

Resultant is from the Latin resultare, resultans (from re,again, back ,and salire, to leap) .

Components.

The components ofaforceare two or more forceswh ich,acting together, will produce the same effectas the given

force.

Component is from the Latin com, together,and ponere,ponens, to put.

Two Forces in the Same I/ine.

IN THE SAME DIRECT ION.

I nf. 1 . The resultant of two forcesacting in the sameline in the same direction isasingle force equal to their

sumacting in the same line in the same direction .

I nf. 2. A heat rowed down stream four milesan hour,

md carried by the current two milesan hour, proceedsatthe rate of six milesan hour.

IN OPPO S I TE DIRECTIONS .

EXPERIMENT 3 7.

Obs. The resultant isafour- inch lead .

1 . This is the resultant of two forcesacting sameline in Opposite directions.

FORCE. 191

2. It equals the difference of the forces,andacts in thesame line in the direction of the greater.

Inf . 1 . Theactual rate of progress is five milesan hour.

Inf. 2. Itwould take,approximately, four hoursand fortyminutes to go twenty-eight miles.

TumParallel Forces.

IN SAM E DIRECT ION.

EXPERIM ENT 3 8.

Obs. The two weigh ts will balancean eight- inch lead

supported from the screw-eye, th ree inches from the end

screw-eye, to wh ich the six- inch lead isattached .

Inf. 1 . The resultant of two parallel forcesacting in the

same direction isasingle force equal to their sum.

I n!. 2. Their resultant isaforce of 300 poundsactingin the same direction ,

inaline one halfas far from the

line of the greater forceas from the line of the smaller.

Two Forcesatan Angle.

1 . In twenty seconds the boat will have been carriedacross the river 120 feet,and down the river 60

feet.

The figure is aparallelogram, with adiagonalrepresented .

3 . The diagonal represents the direction and distanceof theactual motion .

192 ELEMENTARY LESSONS IN PHYS ICS .

4. The sideab represents the direction in wh ich the

rowing would have carried the boat,and the dis

tance Itwould have gone in th ree secondswithoutany current.

The sideac represents the directionand distance of

the motion wh ich would have resulted from the

current without the rowing, in th ree seconds.

Inf. The resultant is less than the sum,and greater thanthe difference of the components.

5 . Its direction lieswith in theanglewhose sides represent

the directions of the components.

VI . GRAVITY.

2. CENTRE OF GRAVITY .

EXPERIMENT 3 9.

The centre of gravityofabodyis the pointatwh ich thebodymaybe supported inanyposition .

3 . LINE OF DIRECTION.

The line of direction ofabodyisavertical line passingth rough the centre of grav1ty of the body.

4 . E!UILIBRIUM.

a. OF A BODY SUPPORTED AT ONE POINT.

EXPER I M ENT 40.

Obs. 1 . It is in equilibrium in everyposition .

Obs. 2. It is in equilibriumwhen the centre of gravity isdirectlyabove or directlybelowthe point of support.



I nf. 4 . A bodywithalarge base is more stable than one

withasmall base, because it ( its centre of gravity) wouldhave to be raised more to overturn it.

Inf. 5 . Thatabodymaybeas stableas possible, its lineof direction must pass th rough the centre of the base.

Inf. 6 . If the line of direction passes outside the base,the bodywill not stand.

Inf. 7. The stability ofabody resting on its base dependsupon its heigh t (the height of its centre of gravity) , thesize of its base,and the nearness of its line of direction

to the centre of the base.

I nf. 8. The legs of chairsand stoolsaremade to slant outward, tomake the base larger,and somake them more stable.

I nf. 9. The line Of direction passed with in the base.

I nf. 10. The step-ladder fell over, because the centre of

gravity (of the young ladyand the step-ladder) changesas

she mounts the steps,and soon the line of direction fallsoutside of the base.

5 . FALLING BODIES.

Inf. 11 . Gravitycauses bodies to fall.1 . Gravityisaconstant force.

Inf. 12. A bodywill fall foratime through theairwithaccelerated velocity.

EXPERIMENT 4 1 .

Obs. The bodyfallswith increasing velocity.

1 . Th isagreeswith the inference.

6 . PENDULUM.

EXPERIMENT 49.

Obs. Theweight swings toand fro.

A pendulum isabody suspended fromafixedswing freely.

GRAVITY. 195

Pendulum is from the Latin pendulus, from pendere, tohang, i. e.

,alittle hanging body.

A vibration isasingle swing of the pendulum.

Vibration is formed from the Latin vibrare, to move toand fro,and ion, theact of.

b. CAUSE OF VIBRATION.

Inf. Gravity carries the pendulum downward through thefirst half of its swing,and its inertiaOf motion carries itonward, until that is overcome bygravity. Then it Swingsback from the same causes,and so continues.

c. RATE OF VIBRATION.

EFFECT OF LENGTH OF ARC .

EXPER IM ENT 4 3 .

Obs. 1,2. The number of vibrationswill depend upon the

length Of the pendulum .

Inf. The rate of vibration is notaffected by the length of

theare through wh ich the pendulum swings.

EFFECT O F W EIGHT OF PENDULUM .

EXPERIMENT 44 .

Obs. Depend upon the length of the pendulum.

I nf. Theweight of the pendulum does notaffect the rateof vibration .

EFFECT OF LENGTH or PENDULUM.

EXPERIM ENT 4 5 .

Obs. 1 . The rate of vibration is diminished.

Obs. 2. The rate of vibration is halfas great.

EXPERIM ENT 4 6 .

Obs. 1 . The pendulum that makes one swing inasecondis 39+ inches long .


Obs. 2. The pendulum that vibrates half seconds is 10inches long.

USE OF PENDULUM .

1 . A pendulum makes the same number of vibrations ineach minute.

2. It vibrates regularly.

3 . Hence it isadapted to measuring time.

A metronome isapendulum used to indicate the time of

apiece of music. It makes one swing for each part of themeasure. It often consists ofasimple string or tape,andaweightattached to one end .

Metronome is from the Greek uérpov, measure,and véuew,

to distribute.

USE IN CLOCKS .

Obs. Connectedwith the upper end of the pendulum rod

isacurved bar called the escapement, with its ends bent

downward soas to form little hooks. Th is escapement isdirectly over one ofaseries of toothedwheelswhich formthe works. Aboutasmall shaft in the works isasteelspring, which is coiled up by turning the shaft by meansof the clock key.

Inf . 1 . The coiled spring tends to unwind .

Inf. 2. The spring is so connected with theworks thatthe uncoiling of it turns the wheels of the works.

Inf. 3 . If there were no pendulum, the spring woulduncoiland the works move rapidly forashort time.

Inf. 4 . When the pendulum swings to the right, the left

end of the escapement comes downagainstateeth of the

wheel andwhen the pendulum swings to the left, the right

end of the escapement comesagainstanother tooth . Be

tween the letting go of one end of the escapement,and thestriking of the other end, thewheel turns just one notch .

The use of the pendulum is to regulate the movement.



Obs. 2. Thewater remainsat the same level in the glasstubeand the tunnel.

e. WATER WORKS FOR C ITIES AND TOWNS .

I II my town the water supply is furn ished from largewells. It is pumped by steam pumpsat the pumping

station,and forced throughapipe to the stand -

pipe,wh ichis located on the top ofah igh h ill. From the stand -

pipe

thewater goes out th rough the large pipes, or mains, in thestreets,and from the mains th rough small pipes into the

housesand roomswhere it is wanted . At intervalsalongthe mainsare located hvdrants, to bring the water to the

surface in the streets for use in extinguish ing fires.

I nf. 1 . The pressure is greatestat the lowest points inthe pipes.

1e . 2. Thewaterwould rise in the pipes ofahouseash ighas it is in the stand -

pipe.

I nf . 3 . Waterwould be thrown h ighest fromahose con

nected withahydrant in the lowest part of the town .

f. SPIRIT LEVEL

Obs. 1 . The spirit levelconsists ofaslightlycurved , shortglass tube, nearlv filled withaliquidand closed ,andacaseofwood, in the upper side ofwhich the tube is set

, so thatthe middle of the bend is the h ighest partwhen th e case isexactly horizontal.

GRAVITY. 99

Inf. Alcohol is better thanwater for th is use because it isnot likely to freezeand break the tube.

Obs. 2. When the bubble is in the middle of the tube, the

case is level, or inahorizontal position .

1 . Placing the level inahorizontal position , one looks

along the top of it over other surfacesand lines todetermine whether theyare level.

g. SPRINGS AND WELLS.

Of thewater that falls upon the landas rain, some evaporates

,some flows down the slopes,and some sinks into the

ground .

I nf. 1 . Waterwill fill the lower part of the hole.

I nf. 2. Thewater in the holewill be on the same levelas in the loose material on the sides of the hole.

ARTESIAN WELLS .

The water wh ich falls upon the exposed portion of the

layer of loose material settles down to the impervious

stratum,works its way down the slope of th is layer,and

fills the loose materialabove it.

I nf. 1 . Thewaterwould flowoutat the surface.

Artesian is from Artesium,theancient name of Artois.

France, where many of these wells have been made.

Inf. 2. G ravitvacts to produce springsandwells.

h . FLOATING AND SINK ING .

EXPERIM ENT 5 2 .

Obs. 1 . A part of thewater runs over into the pan,the spring contracts.

Inf. 1 . A volume of water equal to the volume of

stone is displaced .


Inf. 2. By being immersed in the water the pebble haslost of its weight. (Depends upon its size.)Obs. 2. The spring is stretched justas muchas before

the pebble was immersed .

I nf. 3 . Theweight of the pebble in water, togetherwiththeweigh t of thewater displaced, equals theweight of thepebble inair.

Inf. 4 . The loss ofweight ofasolid immersed equals theweigh t ofan equal volume of the liquid .

Inf. 5. A solid having the sameweightas its own volume

of the liquidwill loseall of itsweight on being Immersed .

I nfs. 6, 7. Itwill floatatanylevel.

Inf. 8. A bodyheavier than waterwill sink inwater.

Inf. 9. A body lighter than waterwill float.Inf. 10. Itwill projectabove the liquid .

I nf. 11 . A bodyhalfas heavyaswaterwillfloatwith halfits volumeabove thewater.

Inf. 12. Tin pansand iron sh ipsare hollow,and maydisplaceavolume of water equal to many times the volume

of thematerial ofwh ich theyare made.

i. SPEC IFIC GRAVITY .

Specific is from the Latin Species,aparticular kind ,andfacere, to make.

a. Find the loss ofweight Of the iron on being immersed

inwater.

6. Divide theweight inair by the loss ofweight inwater.

Inf. 13 . Ifabody floatswith half its volume underwater,its specific gravity is one half.Inf. 14 . If it floatswith one eighth of its volume under

water, its specific gravity is one eighth .

Inf. 15 . If it floats with five sixths of its volume out of

water, its Specific gravity is one sixth .



BAROMETER.

EXPERIM ENT 58 .

Obs. 1 . The mercurynearlyfills the tube.

I nf. 1 . See Inf. Exp. 57.

I nf . 2. The pressure of theair is not great enough to

sustainacolumn of mercuryas h ighas the tube.

Obs. (Heightswill varyat different times.)I nf. 3 . The heigh t of the mercury column depends upon

theamount ofatmospheric pressure.

I nf. 4 . The variation in the height of the mercury column

indicates that the pressure of theair varies.

Barometer is formed from the Greek Ba’pov,weight,andus

’rpov, measure.

EXPERIM ENT 59.

Obs. The falling of the mercuryin the barometer is frequentlyaccompanied by rainand warmer temperature,whilewindsand clearing , coolerweather often comewitharisingbarometer.

I nf. When the “ barometer falls, the weather is likelyto be rainyandwarmer ;and when the “ barometer rises

,

cooler, clearing weather is likely to follow.

PUMPS .

LIFT ING PUMPS .

Suggestion .

Glass tubingabout one inch in diameterand havingamoreeven bore than the lamp ch imneys maybe obtained of dealers in chemicalapparatus. If cut into convenient lengths,

th iswill be better than the ch imneys for making pumps.

EXPER IM ENT 60.

Obs. Thewater follows the piston,and fills the lower partof the tube.

GRAVITY. 203

Inf. Theair, pressing downward upon the surface of the

water, forces it upward into the tube.

EXPERIMENT 6 1 .

Obs. 1 . AS the piston is raised,the valve in the piston

is closedand the lower valve is open. AS the piston is

lowered , the upper valve is Openand the lower valve is

closed .

Inf. 1 . As the piston is raised more room is given to theair belowit,and the upward pressure of theairagainst thevalve becomes less than the downward pressure of the out

sideair upon the valve. At the same time th is greaterpressure of theair upon the surface of the water outside

forces the water up into the tube, push ing theair in the

tube upwardand opening the lower valve. As the piston

goes down , the room belowit becomes lessand the pres

sure becomes greater than that of the outsideair, pressingthe lower valve downand opening the upper one.

Obs. 2. As the piston is raised,water comes up through

the tubeand the lower valve,and thewaterabove the piston( ifany) is lifted h igherand runs outat the spout. Whenthe piston islowered , thewater belowit passesabove throughthe valve.

Inf. 2. The downward pressure upon the surface of the

water outside forces it up through the tube into the cylinder

when the pressure inside is lessened by raising the piston .

When the piston goes downand the pressure in the cylinder

becomes greater than that outsideand closes the valve,there

is no escape for thewater in the cylinder except through the

upper valve.

I nf. 3 . The pressure of theair upon the surface of the

water outside balances th is column ofwater in the pipe.

I nf. 4 . Theatmospheric pressure is not great enough tosustainahigher column ofwater.

ELEMENTARY LESSONS IN PHYSICS .

I nf. 5 . Water could be raisedabout 30feetwithan ordi

narylifting-

pump.

FORCE PUMP.

EXPERIMENT 6 2.

Obs. 1 . As the piston is raised, the valveat the bottom of

the cylinder, or barrel, opens,and some water comes up

through the tube into the barrel. As the piston goes down ,

th is valve closes, the valve in the bottle opens,and some of

the water goes through the tube into the bottle. AS the

working of the piston continues, the water is th rown out of

the tubeat b.

I nf. 1 . As the piston is raised, the pressure of theairbelowit becomes less than the outside pressure upon the

water,and thewater is forced up th rough the tube into the

cylinder. As the piston is pressed down, the pressure insidebecomes greater than that outside, closing the valve in thecylinder, forcing open the valve in the bottle

,and sending

the water from the cylinder into the bottle.

Obs. 2. The upper part of the bottle is filledwithair.

I nf. 2. When thewater is forced into theair-chamber, theair in it is compressed . It tends to expand ,and forces thewater out th rough the tube inacontinuous stream. Theairformsan elastic cush ion ,

and prevents the jarand strainupon the pumpwh ich would come in starting the motion of

the water with each stroke of the piston .

I nf. 3 . Force pumpsare usedat pumping-stations.

1 . A fire- engine for throwingwater consists of two forcepumps wh ich alternately force water intoalargeair- chamber, or dome, from wh ich it is driven out

by the expansive force of theair.



as far,and in the third position it moves th ree timesas faras the load.

EXPERIMENT 6 6 .

Obs. 1 . A power of 2 unitsapplied 2 inches from the

fulcrum will balanceaload of 2 units placed 2 inches

from the fulcrum.

Obs. 2. Applied 4 inches from the fulcrum,apower of

2 units will balanceaload of 4 units placed 2 inches fromthe fulcrum.

Obs. 3 . Applied 6 inchesfrom the fulcrum,the same power

will balanceaload of 6 units 2 inches from the fulcrum.

EXPERIM ENT 6 7 .

Obs. When the load is placed twiceas far from the ful

crum,the power requiredatany point to balance it is twiceas great.

0. APPLICATIONS .

CROWBAR.

A crowbar isalever of iron made heavierand squaretoward one endand cylindrical toward the other end . The

heavier end is flattened toan edge, so that it maybe insertedinto small crevices. It is used to raise ormove objects shortdistances.

STEELYARD .

In the steelyard the fulcrum is between the loadand thepower. The load is suspended fromahookattached to theshorterarm of the lever near the fulcrum. The power isapplied on the longerarmat such distance from the fulcrum

that it will balance the load. The weight of the load isshown byagraduated scale on the longarm,

with the

weights wh ich the power will balanceat certain points

marked upon the scale.

The steelyard usuallyhas two books, from either ofwh ichthe load maybe suspended . The one nearer the fulcrum is

SIMPLE MACHINES . 207

forweigh ing heavyloads,and the one farther from the ful

crum forweigh ing light loads.

2. WHEEL AND AXLE.


EXPERIM ENT 6 8 .

Obs. 1 . A power of 2 units on the wheelwill balanceaload of 6 units on theaxle.

Obs. 2. A power ofalittle more than 2 unitswill raisethe load .

Obs. 3 . In moving the load 1 inch the power moves 3inches.

1 . The load isapplied 1 inch from theaxis.

2. The power isapplied 15 inches from theaxis.

I nf. 1 . Theaxis of thewheelandaxle corresponds to the

fulcrum of the lever.

I nf. 2. The radius of theaxle in th is experiment corre

sponds to the shortarm of the lever.

I nf . 3 . The radius of thewheel corresponds to the longarm of the lever.

In theabove experiment the p ower wasapplied th ree

timesas far from theaxisas the load,andapower one

thirdas greatas the load was required to balance it.I nf. 4 . The relation of power to load in the wheelandaxle is the sameas in the lever.

I nf. 5. A load can be moved butashort distance withoneapplication ofalever.

I nf. 6 . With oneapplication of thewheelandaxlealoadcan be movedalong distance.

I nf. 7. Thewheelandaxle is betteradapted for movingloads long distances.

Inf. 8. The lever is more convenientlyand quicklyapplied when onlyaslight change of position is desired.


EXPERIMENT 69.

Obs. 1 . A power of 9units on theaxlewillbalancealoadof 3 units on thewheel.Obs. 2. A power ofalittle more than 9units on theaxlewill raiseaload of 3 units on thewheel.Obs. 3 . In raising the load 6 inches the power moves 2

inches.

1 . These resultsagreewith those obtained in the lever.

c . APPLICATIONS .

Awindlass is used for drawingwaterand raisinganchorsand other loads,acapstan is used for moving buildings,awinch for turningagrindstone,abit-brace for boring holes,andawater-wheel for turning machinery.

3 . PULLEYS .

a. DESCRIBE.

A pulley isawheelwithagrooved circumference over

wh ichacord may pass.

b. RELATION OF POWER TO LOAD IN FIXED PULLEYS .

EXPERIM ENT 70.

Obs. 1 . A power of 6 unitsappliedat the other endwillbalance the load .

Obs. 2. A power ofalittle more than 6 units will raisethe load .

I nf. To raiseaload, frictionand inertiaof rest must be

overcome ; therefore more power would be required thanwould be necessary to balance it.

EXPER I MENT 7 1 .

Obs. A power equal to the load is required to balancealead over th ree fixed pulleys.



1 . It equals one sixth of the load .

2. The height of the plane equals one sixth of the length

of the plane.

Inf. The power required is less than the load because theplane supportsalarge part of the load .

EXPERIM ENT 75 .

The power required to balance the load equals one third

of the load,and the height of the plane equals one third of

the length of the plane.

6. USE.

1 . The slope ofahill is used in raisingacarriage load toits summit, the grade ofarailroad track is used in

raisingatrain toah igher level,and inclined planesare used for loading heavy casks,and for raisingcarriages to the upper stories of buildings.

Inf. The plane supportsalarge part of the load,andenablesacomparatively small power to raise it.

5 . SCREW .

The general shape of the screwis cylindrical.A spiral projection windsaround the cylinder.

The upperand lower surfaces of th is projection inclineupward to the right,and form inclined planes.

In the nut there isagroove for the thread of the screwto fit into.

The screwrests upon the under side of the th read .

When the screwis turned , the under side of the th readslides over the inclined planewh ich forms the lowerside of the groove in the nut.

SIMPLE MACHINES. 211

6 . WEDGE.

1 . Awedge is shaped likeasmall inclined planewith itsbase, or like two inclined planes with their basestogether.

2. It is used for Splitting wood, splitting rocks,and

raising loads.

The load is not moved over thewedge.

Thewedge ismoved .

It is drivenwithahammer or beetle.

APPLICATIONS OF THE SIMPLE MACHINES .

1 . Pulleys,wheelandaxleand inclined planesare used

to raise loads to the upper stories of buildings.

2. A door keyisaform ofwheelandaxle, though it isused to move the load butashort distance.

3 . Thewheelandaxle is used for raisingand loweringthe wicks of lamps.

4 . Thewedge is used for splitting wood .

5. A form ofwheelandaxle, calledacapstan , is used in

movingabuildingalong the street.

6 . A lever is used inworkingajack -screw.

7. An inclined planewould be used in loadingabarrel ofOil uponatruck .

8. A long lever, calleda“ well sweep, andaform of

wheelandaxle, calledaWindlass, have been used

for raising “ the old oaken bucket ” from the well.9. Inalever the resistance of friction is less than inany

other simple machine.

10. No machine can furnish energy.


VIII . HEAT.

1 . SOURCES OF HEAT .

EXPERIM ENT 76 .

Obs. The hand feelswarmer in the sunsh ine than in theshade.

The sun isasource ofheat.

EXPERIMENT 77 . (See Experimen t

Friction isasource of heat.EXPERIM ENT 78.

Obs. The nail becomes heated by hammering .

Inf. 1 . Hammering, or percussion ,isasource of heat.

1 . Two other sources of heat noticed in our study of Cor

relation Of Forceswere chemicalactionand electri

city (lightning) .

2. The sources of heatwe have consideredare the sun ,

friction , percussion , chemicalaction,and electricity.

I nf. 2. Most heat is derived from the sun .

Inf. 3 . The next greatest source of supply is chemicalaction .

2. EFFECTS OF HEAT.

a. EXPANS ION.

(1) OF SOLIDS .

EXPERIM ENT 79.

Obs. 1 . The marble drops through the heated ring .

Inf. 1 . The ring has grown larger, or expanded, from the

heat.

Inf. 2. One effect of heat is that it expands solids.

Expansion is from the Latin em,out

, pandere, to Spread,and ion, theact of theact of spreading out.



Evaporation is from the Latin e (for em) , out, vaporare, toemit vapor,and ion, theact of.

EFFECT OF VAPORI ZATION ON ADJACENT B ODIES .

EXPERIMENTas.

Obs. Thewater under the crystal freezes.

I nf. 1 . It is caused by the evaporation of the ether.

1 . Sprinkling the floor or street cools theairwh ile thewater is evaporating.

2. A summer shower cools theair in the sameway.

Inf. 2. The heat required to change the water fromaliquid toavapor is taken ch iefly from the surroundingair.

Artificial ice is madeaccording to th is principle : i. e.,

that evaporation takes heat fromadjacent bodies. A very

large tank of brine water saturated with salt has run

ning th rough itaset of pipes. Theair in these pipes

is exhausted by means ofan engine,and thenammoniais introduced ,wh ich suddenly changes to gas in the vacuum.

This cools the pipes to suchadegreeas to make the temperature of the brine much belowthe freezing point, the

sameas the salt wateraroundan ice-cream freezer. Nowset into th is brine, between the pipes,are cans (shapedlike the cakes of ice we wish to make) filled with clear,fresh water. Iceat once begins to ‘form on the inside of

these cans,and in forty- eight hours or so thewater in the

cans is entirelyfrozen ,making solid cakes of ice. The cans

,

of course,are openat the top.andafter exposing them to

the warmairafewminutes, the cakes slide out.

CONDENSAT ION.

EXPERIMENT so.

Obs. Drops ofwater form on the cold glass.

Inf. The vapor coming in contactwith the cold surfaceis cooled to suchadegree that it changes back towater.

HEAT . 217

1 . A vapor is changed toaliquid.

Condensation is from the Latin con,with

,densare, to

make dense,and ion , theact of.

Drew, DEwPO INT, FROST, C LOUDS, RA IN, HAIL, SNow.

EXPER IM ENT oo.

Inf. 1 . The cool can takes heat from the vapor in theairin contactwith it,and the vapor is condensed on the outsideof the can .

Inf. 2. The surface of the grass cools off more rapidlythan theair,and the vapor of theair is condensed on the

cool grass.

Inf. 3 . Frost is frozen dew.

I nf. 4 . Thewarmair is cooledwhen it comes in contactwith colderair.

Inf. 5 . The moisture of thewarmair is condensed .

Inf. 6 . Rain is formed by the moisture ofawarmer bodyofair being condensedas it comes in contactwith colder

air, thus forming drops, wh ich fall.Hail is frozen drops of rain .

Snowis frozen vapor before it has formed into drops.

3 . TRANSFER OF HEAT.

a. RADIATION.

EXPERIMENT OI .

Obs. The hand feelswarmer.

I nf. It receives heat from the heated body.

EXPERIM ENT 92.

Obs. Heat is felt inwhatever direction the hand is heldfrom the heated body.

Inf. Heat passes inalldirections from heated bodies.


EXPERIM ENT 93 .

Obs. Not much heat is felt.I nf. 1 . Heat passes in straight lines from heated bodies.

Radiation is from the Latin radiare, to emit rays,and

ion .

Radiator is from radiare,and or,thatwh ich .

Fire screens protectagainst the radiated heat in directionswhere the heat is notwanted .

b. CONDUCTION.

EXPER IM ENT 94 .

Obs. The marble nearest the flame dropped off first, then

the one next,and so on,untilall had melted off.

Inf. 1 . Heat is carried from the flame through the rod ,

thus melting the wax.

Conduction'

is derived from the Latin conducere,to lead,and ion, theact of.

GOOD AND POOR CONDUCTORS .

EXPERIM ENT 95 .

The heat is conducted more readily th rough the iron thanth rough the slate.

Conductor is derived from conducere, to lead ,and or, that

wh ich .

USES OF POOR CONDUCTORS .

EXPER IM ENT 96 .

Obs. 1 . The temperature ofall the bodies is the same.

Obs. 2. Theydo notfeelequallywarm.

Inf. 1 . Some of them—the iron , for instance— conduct

the heat from the check more rapidly than some of the

others,as the woollen .



and forces itaway. This in turn becomes heated,and is

forcedaway in the same manner.

I nf. 2. Ocean currentsare caused by the unequal heatingof different parts of the ocean . The equatorialwaters become heated by the sun ,and the colder, heavierwaters flowin under themand force themaway, thus forming currents

inamanner similar to whatwe sawin the pan of water,

but onagrander scale.

EXPERIMENT 100.

Obs. Thewater moves rapidly through the tube,and isreplaced with water from the test tube.

I nf. The portion in the flame becomes heated,and is

forced upward by the cooler water.

1 . A furnace has in the upper partastrong boilerwithpipes leading to the rooms to be heated,and thence back

again to theboiler. Another pipe

fromatank (S ) inapart of thehouse h igher than any part tobe heated , serves to communicatepressureand to relieve the ex

pansion of the water,as it is

heated. The pipes and boiler

are filled with water,and as it

becomes heated it begins to cir

culate th rough the pipes leadingto the rooms,aswe sawit circulate in the glass tubing inthe last experiment. Th is circulation of hotwaterwarms

the rooms from the radiating pipes (R) in each room .

NOTE .—The diagramsand explanations for heating by hotwater,and those wh ich followin the f urnishing of hot water fromakitchen

range,and heating byfurnace, only explain the principleswh ich are“ ential in the endless variety in use.

HEAT 1

R isakitchen range, B the copper cylinder, or boiler.

This is suppliedwith water byapipe from the tank (T) inthe upper part of the house, the coldwaterfrom the tank being taken inat the base of

the boiler. A pipealso leads out of the baseof the boiler, th rough the range close to the

fire,and turns back into the boilerand runs

up toward the top, inside. Other pipes leadsent from the top of the boiler to different

parts of the house,where the warm watermay be drawn from faucets (F ) . The supply pipe keepsthe boilerandall the pipesalways full,and furnishes pressure to carry the water toall parts of the house. The

water in the short pipe in the range becomes hot,and israpidlyforced through by coolerwater from the lower partof the boiler. Thusaconstant circulation is maintained,keeping thewater in the boileralways hot. Thewater inthe pipeswhich supply th e rooms becomes cooledwhen the

pipesare not drawn from ; butafter runningalittle thiscoolerwater is drawn off

,and hotwater from the boiler is

supplied.

DRAUGHTS .

EXPERIMENT 101 .

Obs. 1 . The end of the paper moves upward.

Obs. 2. The end of the paper moves upward .

I nf. Theair inside the ch imney, becoming heated, isforced upward by the denser coolair from outside, whichcrowds in

,and this in turn becomes heated, and thus

createsaconstant current or draught ofair.

EXPERIM ENT 102.

Obs. There isadraught th rough the flue ofan oil stove.

Inf. 1 . It is produced by the heating of theair in the

202 ELEMENTARY LESSONS IN PHYS ICS .d

passagesabove the flame,and the flowing in of cooler,

heavierair towards the place occupied by th is warm,

lighterair.

I nf. 2. The draught throughastoveand up the chimneyis precisely the sameas in the oil stoveand lamp ch imney.

1 . Theair near the stove becomeswarmer than theairfartheraway from it

,and theair from the colder

parts of the room moves toward the stove,and thataroundandabove the stove moves upward . Ifanypart of the room is colder than other portions, asapart nearacoldwindow, —the current toward thestove ismore marked from that direction.

Inf. 3 . Th is is caused by the heatingand expanding of

theairabout the stove.

2. A furnace (A) is inclosed by brick or Sheet iron,

soas to form anair chamber(B ) around the outside. Thisair in the chamber becomes

heated,and is forced upward

through the pipes (D ) by the

cooler outsideair which enters

through the cold-air box ( C) .

Fireplaces (F) , or some other

means ofallowing theair to

escape from the rooms,aid in

maintaining aconstant circulation of warm freshaIr so

essential to health in every house.

W INDS .

EXPERIMENT 108.

Obs The flame points from the cool room towards thewarm one “ hen heldat the bottom of the doorway,andfrom the warm room towards the cool one when heldatthe top.



I nf. 1 . Theadditional heatapplied is used in converting

thewater toavapor.

Latent heat is the heat which disappears in melting or

vaporization .

EXPERIM ENT 105 .

Obs. 1 . The quantityofwater in the flask has diminished, .

and that in the can has increased .

Thewater in the can has grownwarm.

Obs. 2. The temperature of thewater in the flask remainsthe same.

Inf. 1 . The heatappliedwas used in changing thewaterto steam .

Inf. 2. The steam passed th rough the tubeandwas condensed in the can .

I nf. When the vapor was condensed, the latent heatwas set free,and ward the water of the can .

Steam heatingapparatus consists ofaboiler (B )andafire-box (F ) , similar to those ofasteam engine,with steampipes leading from the top of the boiler to the radiators inthe rooms,and return pipes to carrythe condensed steamfrom the radiators back to the lower part of the boiler.

MAGNETISM . 225

As the temperature of the radiators is lower than thatatwh ich steam . can exist (212

°

the steam is condensed,

giving out its latent heat of vaporization to the radiators,

wh ich in turn communicate it to theair of the rooms.

EXPERIMENT 106 .

Obs. 1 . Thewater isalittlewarmer than the ice.

Obs. 2. The contents of the test tubewh ich contained theice haveabout the same temperatureas before, while the

water in the other test tube has becomeas hotas that inthe can .

I nf . 1 . The heat received by the ice has been used in

changing it into liquid .

I nf. 2. The deepest snow or the th ickest ice wouldmelt instantlywhen the temperature reached th e melting

point (3 2°

E ) , if no heatwereabsorbedas latent heat inmelting.

IX. MAGNETISM.

1 . MAGNETS .

b. KINDS OF MAGNETS .

TEMPORARY .

EXPER I M ENT 107 .

Pupils should be cautioned to use iron nails not steel

wire—in th is experiment.

Obs. 1 . The second nail sticks to the first.

Inf . 1 . The first nail has becomeamagnet.

Obs. 2. The second nail drops from th e first.

Inf. 2. The first nailwasatemporarymagnet.

1 . It was produced by being brought in contact withamagnet.


PERMANENT .

EXPERIMENT 108.

Obs. 1 . The iron filings stick to the end of thewire.

I nf. 1 . Thewire has becomeamagnet.

Obs. 2. The iron filings still stick to the end of thewire.

I nf . 2. Thewire isapermanent magnet.1 . I infer th is fact.

2. Th is magnet was produced by rubbing the steelwirein one direction with the end ofamagnet.

c. POLES OF A MAGNET.

EXPE RIM ENT 109 .

Obs. The filings cling to the magnet ch ieflyat the ends.

I nf. The magnetism is manifest ch ieflyat t he ends of themagnet.

EXPERIM ENT n o.

Obs. The magnet points nearly northand south .

d . LAW OF MAGNETS .

EXPER IM ENT 1 1 1 .

Obs. When two north poles or two south polesare broughtnear each other

,theyflyapart ; butwhenanorthandasouth

poleare brought near each other they rush together.

Inf. Like poles repel each other,and unlike polesattracteach other.

2. TERRESTRIAL MAGNETISM.

a. MAGNETIC NEEDLE.

EXPERIMENT 1 1 2 .

Obs. 1 . Thewire magnet takes the same directionas thebar magnet.

Obs. 2. The needle changes its direction with the barmagnet.

I nf . The bar magnet controls the direction of the needle.



2. ELECTROSCOPES .

a. PITH - BALL

EXPERIM ENT 1 1 7 .

Obs. The pith-balls Spreadapartand flyto the ch imney;

butafter touch ing it theyflyoffagain .

5. BALANCED BAR.

EXPERIMENT 1 18.

Obs. The end of the bar comes up to the ch imney.

3 . KINDS OF ELECTRIC ITY .

EXPERI M ENT l 19.

Obs. 1 . The pith-balls fly to the ch imney, but soon flyoff.

Afterafewseconds they come to the ch imneyagain .

Obs. 2. The pith-balls move to the sealingwaxand thenaway, justaswith the ch imney.

EXPERIMENT 1 20.

Obs. The pith-balls move backand forth between the

chimneyand the sealingwax .

I nf . The pith- balls are attracted by the sealing wax

when theyare repelled by the ch imney,and vice versa.The electricity in the sealing wax must be different fromthat in the ch imney.

EXPERIMENT 1 21 .

The end of the balanced bar isaffected in the samewaysin wh ich the pith -ballswere.

EXPERIMENT 1 22.

Negative electricity is excited in the silk pad whenrubbed with the ch imney,and positive when rubbed withthe scalingwax.

FRICTIONAL ELECTRIC ITY. 229

Positive electricity is excited in the flannelwhen rubbed

with the chimney,and the same when rubbed with the

sealing wax.

4 . LAW OF ELECTRIC ITIES .

EXPERIM ENT 123 .

Obs. 1 . The ch imneyon the hooks turnsaway from the

other.

Obs. 2. The stick of sealingwax on the hooks turnsawayfrom the other.

Obs. 3 . The ch imney, when on the hooks, turns towardthe excited sealingwax ;and the sealingwax,when on the

hooks, turns toward the excited ch imney.

I nf. Bodies charged with the same kind of electricityrepel each other,and bodies charged with unlike electrici

tiesattract each other.

5 . CONDUCTION.

CONDUCTORS AND INSULATORS.

EXPERIM ENT 1 24 .

The bar is notaffected .

The bar is notaffected .

EXPERIM ENT 1 25 .

The electroscopesare slightlyaffected.

EXPERIMENT 1 26 .

The electroscopesareaffected, but more when near thekey.

Inf. 1 . The electricities of the excited bodiesact over

the rule, the pencil,and the keyupon the electroscope, but

do notact over the glass tubing.

Glass isan insulator,the ruleand the pencilare poor

conductors,and the key isagood conductor.


2. ELECTROSCOPES .

a. PITH—BALLEXPERIMENT 1 1 7 .

Obs. The pith-balls spreadapartand flyto the ch imney;

butafter touch ing it theyflyofl"again .

6. BALANCED BAR.

EXPERIMENT 1 18.

Obs. The end of the bar comes up to the ch imney.

3 . KINDS OF ELECTRIC ITY .

EXPERI MENT 1 19.

Obs. 1 . The pith-balls fly to the ch imney, but soon fly off.

Afterafewseconds they come to the ch imneyagain .

Obs. 2. The pith-balls move to the sealingwaxand thenaway, justaswith the chimney.

EXPERIMENT 1 20.

Obs. The pith-balls move back and forth between the

chimneyand the sealing wax .

Inf. The pith-balls are attracted by the sealing wax

when theyare repelled by the ch imney, and vice versa.The electricity in the sealing wax must be different fromthat in the chimney.

EXPERIMENT 1 21 .

The end of the balanced bar isaffected in the samewaysin wh ich the pith -ballswere.

EXPERIMENT 1 22.

Negative electricity is excited in the silk pad whenrubbed with the ch imney,and positive when rubbed withthe sealingwax.



Inf. 2. Glass bottlesare used in electroscopes in order

that the electricity may not be dissipated byacting over

the electroscope upon other bodies.

I nf . 3 . Pith -balls in contactwithan electrified body he

come electrified , or charged with the same kind of electricity

which is in the body,and soare repelled from the body.

The two pith -balls become charged with the same kind of

electricity,and repel each other.

Inf. 4 . Lightning rodsare electric conductors,and the

electricities of the earthand theairact over them insteadof over the building or through it.

6 . INDUCTION.

EXPERIMENT 127 .

Obs. The end of the bar moves up to the can .

I nf. Electricitymust have been developed in the can bytheapproach of the excited chimney.

If the excited ch imney is used to induce electricity in the

can ,and the excited sealing wax is held just beyond the

electroscope in th is experiment, the electroscope isattractedby thewaxwhen it is repelled by the can ,

andattracted bythe can when it is repelled by thewax . This indicates thatthe electricityat that end of the can is unlike the electricity

of thewax. Hence it must be positive.

Obs.and Inf. 2. When the electroscope is brought nearthe other end of the can, it isaffected . Hence there must

be electricityat that end of the can.

Obs.and Inf. 3 . If the pith-ballsare placed between the

chimneyand the end of the can , they move from one to

the other.

The electricityat that end of the can must be unlike thatof the ch imney. It is negative.

In the same way it may be shown that if the excited

VOLTAIC ELECTRIC ITY. 23 1

wax is used in place of the ch imney, positive electricity is

developedat the end of the can near thewax ,and negativeelectricityat the other end .

I nf . 4 . The first effect of bringingan excited body nearan insulated body is to develop upon the insulated body

electricityof the opposite kindat the end near the excited

body,and electricity of the same kindas in the excited

bodyat the other end .

Inf. 5 . The electricitydeveloped on the Side of the pith

balls or bar next to the excited body is unlike that of the

excited body,and that on the other Side is like that of theexcited body. As the unlike electricitiesare nearer togetherthan the like electricities, theattraction is stronger thanthe repulsion ,and the bodies come together. When the

bodies come in contact, the electricity on the side of the

pith-balls next to the excited body is neutralized by

the opposite electricity,and the pith-ballsare left charged

with electricity like that of the excited body,and arerepelled .

XI . VOLTAIC ELECTRICITY.

1 . VOLTAIC ELEMENT .

EXPERIM ENT 128.

1 . Th is Voltaic element consists ofazinc plateandacopper plate connected byacopper wire,and in

serted in asolution of potassium bichromateandsulphuricacid .

2. HOW PRODUCED .

Inf. The electricitywas produced bychemicalaction .


3 . EFFECTS .

a. MAGNETIC EFFECTS.

1 . Voltaic electricity changes the direction of the magnetic needle.

EX PERIMENT 1 29.

Obs. 1 . The bits of iron stick to the end of the rod.

Obs. 2. They stick to the other end .

Inf. 1 . The rod has becomeamagnet.I nf. 2. The rodwas madeamagnet bytheaction of the

Voltaic electricity.

Obs. 3 . The iron drops from the redwhen thewire is cut.

Obs. 4. The rod nowattracts iron .

Obs. 5 . The tack dropsas soonas the ends of the wireare separated.

I nfl 3 . The rod loses its magnetism as soon as the

connection is -broken .

1 . Voltaic electricity turns the magnetic needle,andproduces electro-magnets.

b. THERMAL EFFECTS.

EXPERIM ENT 1 3 0.

Obs. The platinum wire feels hot.

Inf. Thewirewas heated by the electricity.

0. LUMINOUS EFFECTS.

1 . Incandescent electric lightsare produced bytheactionof electricity th rough carbon filaments, which it

beats toawh ite heat.Lightning,arc lights, and flashes of lightaroundtrolley Wiresand electric car railsare produced

by electricity.


23 4 ELEMENTARY LESSONS IN PHYS ICS .

I nf. 2. The vibrations of the vocal cordsare transmittedthrough theair to the paper.

I nf. 3 . The vibrations of the objects will cause theairbetween themand the drum to vibrate

,and the vibrations

will thus be communicated to the drum .

1 . A man was choppingwoodaboutaquarter ofamilefrom the observer, on the opposite side ofapond .

When the sound of the stroke reached the observer,

theaxewas raised foranother blow. It tookaboutasecond for the sound to be transmittedacross thepond .

3 . VIBRATING STRINGS .


EXPERIM ENT 1 3 7

string vibratesandatone is heard .

string vibrates fartherand the tone is louder.

string vibrates still fartherand the tone is

The loudness ofatone depends upon theamplitudeof the vibrations.

b. PITCH OF TONES .

EXPER IM ENT l 3 8.

1 . Whenaheavier string is used , the tone is lower.

I nf . Light strings produce h igh tones.

EXPER I M ENT l 3 9 .

1 The tone is h igher than that produced by the longerstring.

2. The tone produced is still h igher.

I nf. The shorter the string the h igher the tonewhich itproduces.

SOUND . 235

EXPERIM ENT 1 40.

The tone produced by the 8- inch string isan octaveabove

that produced by the 16 - inch string .

EXPERIMENT 1 4 1 .

068. 2. A h igher tone is produced.

Obs. 3 . A still h igher tone is produced .

Inf. The pitch of the tone is raised by increasing thestretching force of the string.

EXPERIM ENT 14 2.

1 . The second tone isan octaveabove the first.

2. The length of the strings, the weight of the strings,and the stretching forceafiect the pitch of tones.

Light, short, tight strings produce h igh tones.

Long, heavy, loose strings produce lowtones.

The strings ofapianoare varied in lengthandweightto produce the difierent tones.

6 . Pianosare tuned bytigh tening or loosening the strings

just enough to produce the right tones.


EXPERIM ENT 1 4 3 .

Obs. A tone is produced .

EXPERIMENT 144 .

Obs. The sand dancesabout the paper.

I n!. Theair in the pipe is vibrating,and these vibrationsare communicated to the paperand the sand.

EXPERIMENT 1 4 6 .

The tone is lower than that produced bythe smaller bottle.

EXPERIMENT 1 4 7 .

Obs. 1 . The tone is h igher than that produced by the

empty bottle.

g, r : rmgxrxar Lassoss lx rm'

slcs.

1 2. Th e VII-rat . us of the vocal cordsare transmittedtineair tn tl.e pat-T .

Th e x ii-m t: of the objects will cause theairo maal tle d rum to t ibrate,and the vibrationsEr C 4 20 11 (0 1110 drum.

ci. o

g-

plngan daboutaquarter ofamilekw rwr. on the opposite side ofapond.

s‘ d of the stroke reached the observer,aw L n fu ranother blow. It tookabout

3 x x‘ a! fu r the sound to be transmittedacross the

3 . VlltRATlNG STRINGS .

a. O F TONES .

EXPER IM ENT 1 3 7 .

. i I : ibm tesandatone is heard .

Ei-m tes fartherand the tone is louder.

str t vmm tes still fartherand the tone is'I an O

.

l- ' ll-I!

I f . T h e ln ltullle\s ofa10 210 depends upon theamplitude(‘I I II ?

I I‘ITt

‘

n O F TONES .

X‘PER I‘ KRT 1 3 8.

1 . 110“ ah t‘at‘ it‘r string is used . the tone isI n t . L ig h t SH" ;no punitive h ig h tomes.

RKPKR

1 Th ? tune ts lugstring

The tone

I n f. Tl




I nf . 3 . The vibrations of the objects will cause theairbetween themand the drum to vibrate,and the vibrationswill thus be communicated to the drum .

1 . A man was choppingwoodaboutaquarter ofamilefrom the observer, on the opposite side ofapond .





EXPERIM ENT 1 3 7 .

string vibratesandatone is heard.




b. PITCH OF TONES .

EXPER IM ENT 1 3 8.



EXPERIM ENT 1 3 9.

1 The tone is h igher than that produced by the longerstring.


I nf. The shorter the string the h igher the tonewhich itproduces.

SOUND. 235

EXPERIM ENT 1 40.

The tone produced bythe 8- inch string isan octaveabove

that produced by the 16 - inch string.

EXPERIMENT 1 4 1 .

068. 2. A higher tone is produced.



EXPERIM ENT 1 4 2.


2. The length of the strings, the weight of the strings,and the stretch ing forceafiect the pitch of tones.



The strings ofapianoare varied in lengthandweightto produce the different tones.

6 . Pianosare tuned bytightening or loosening the strings



EXPERIMENT 14 3 .


EXPERIMENT 144 .


I nf. Theair in the pipe is vibrating,and these vibrationsare communicated to the paperand the sand.

EXPERIMENT t 4e.

The tone is lower than that produced bythe smaller bottle.

EXPERIM ENT 1 4 7 .


empty bottle.



I nf . 3 . The vibrations of the objects will cause theairbetween themand the drum to vibrate,and the vibrationswill thus be communicated to the drum.

1 . A manwas choppingwoodaboutaquarter ofamilefrom the observer, on the opposite side ofapond .





EXPERIM ENT 1 3 7

string vibratesandatone is heard.




b. PITCH OF TONES .

EXPER IM ENT 1 3 8.

1 . Whenaheavier string is used, the tone is lower.


EXPERIM ENT 1 3 9 .

1 The tone is h igher than that produced bythe longerstring.


I nf. The shorter the string the h igher the tonewh ich itproduces.



I nf. 2. The vibrations of the vocal cordsare transmittedth rough theair to the paper.

I nf . 3 . The vibrations of the objects will cause theairbetween themand the drum to vibrate,and the vibrationswill thus be communicated to the drum .

1 . A manwas chopping woodaboutaquarter ofamilefrom the observer, on the opposite side ofapond.





EXPERIMENT 1 3 7 .

string vibratesandatone is heard .




b. PITCH OF TONES .

EXPER IM ENT 1 3 8.



EXPERIM ENT 1 3 9.

1 The tone is h igher than that produced bythe longerstring.


I nf. The shorter the string the h igher the tonewh ich itproduces.

SOUND . 235

EXPERIM ENT 1 40.

The tone produced bythe 8- inch string isan octaveabove

that produced by the 16 - inch string .

EXPERIMENT 1 4 1 .

Obs. 2. A h igher tone is produced .



EXPERIMENT 14 2.


2. The length of the strings, the weight of the strings,and the stretch ing forceafiect the pitch of tones.



The strings ofapianoare varied in lengthandweightto produce the difierent tones.

6 . Pianosare tuned bytigh tening or loosening the strings



EXPERIMENT 14 3 .


EXPERIMENT 144 .


I n!. Theair in the pipe is vibrating,and these vibrationsare communicated to the paperand the sand.

EXPERIMENT 1 4a.The tone is lower than that produced bythe smaller bottle.

EXPERIMENT 1 4 7 .


empty bottle.

ELEMENTARY LESSONS IN PHYSICS .

Obs. 2. The tone is still higher.

I nf. The longer the organ pipe the lower the tone,andthe shorter the pipe the h igher the tone.

EXPERIMENT 1 48 .

Obs. The lowest tone produced bythe closed pipe isanoctave lower than that produced by the open pipe.

Inf. Short, open pipes produce h igh tones,and long,

closed pipes produce lowtones.

XIII . LIGHT.

SOURCES .

The sun, stars,and intenselyheated bodies originate light.

The moon,wooden blocks,and stones

,at ordinary tem

peratures, do not originate light.

1 . All light comes originallyfrom luminous bodies.

2. The sunand starsare natural sources of light.

3 . The ch iefartificial sources of lightare combustionandelectricity.

2. TRANSMISSION.

a. MEDIUM—TRANSPARENT ; TRANSLUCENT.

EXPER I MENT 1 49.

Obs. The ligh t itself cannot be seen .

EXPERIM ENT 1 50.

Obs. Nearlyor quiteall of the light passes through theglass.

1 . Aboutall of it passes through theair.

EXPER I M ENT 1 5 1 .

Obs. Onlyapart of the light passes th rough the colored

glassand the paper.



on the right. Thusan inverted image of the flame is formedupon the screen .

Obs. 2. The nearer the screen is to the box the smallerthe image,and the farther it is from the box the larger theimage.

Inf. 2. From theabove diagram itwill be seen that nearthe box the rays have separated but little,andwould formasmall image uponascreen ; wh ile farther from the box

theyhave separated more,and would formalarger imageuponascreen.

EXPERIMENT 15 5 .

Obs. Smaller inverted images of the outside objectsareformed upon the screen.

f. SHADOW, UMBRA, AND PENUMBRA.

EXPERIM ENT 1 56 .

Obs. Ifalittle sphere is held before the flame,adarkcircle smaller than the sphere is formed on the screen ,andalarger concentric circle not so dark . As the screen is

moved fartheraway, the dark circle grows smaller,and thelighter circle grows largerand less distinct.

Inf. Since the light passes from the flame in straightlines, it willall be shut off fromaconical-shaped space

beyond the sphere having itsapexat c ;andaportion of

the light from the flamewillbe shut off from aspacehaving the shape of the frue

tum ofacone with its baseupon the screen . Thus the

appearances which were seen upon the screen would be

produced.

LIGHT . 23 9

g . ECLIPSE or THE MOON.

The moon isan illuminated body.

Its light comes from the sun .

The earth is Opaque.

There must beashadowon the side of the earthawayfrom the sun .

The earth is smaller than the sun .

The earth’s umbramust be conical.The earth’s penumbramust have the form of the frustum

ofaconewith the baseaway from the earth .

At certain times the moon passes th rough the earth’sshadow,and is not then illuminated by the sun . It is

said to be in eclipse. (See Astronomies.)

h . ECLIPSE OF THE SUN.

The umbraand penumbraof the moonare similar inform to those of the earth , but the umbrais smaller.

At certain times the moon comes directlybetween the sun

andapart of the earth ; i . e. ,aportion of the earth comes

into the moon’s shadow,andapart orall of the sun is

hidden , or in eclipse.

i. VELOC ITY OF LIGHT .

The velocity of 1ight= 186,000,000 miles + 996= more

than miles per second.

j. REFLECTION or LIGHT .

EXPERIMENT 1 5 7.

Obs. The beam of light is turned back from the mirror.

A mirror isasmooth , polished surface.

It turns back the rays of light in regular order.

LAW OF REFLECTION.

Theangle of incidence equals theangle of reflection.


DIFFUSED LIGHT.

EXPERIM ENT 1 5 8 .

Obs. The light is not reflected regularly.

IMAGE OF A PO INT B Y A PLANE MIRROR.

EXPERIMENT 1 59.

Obs. The image of the point is inaline perpendicular tothe mirror passing through the point of the pencil,andasfar beh ind the mirroras the point is in front of it.

IMAGE OF AN OBJ ECT BY A PLANE MIRROR.

EXPERIMENT 1 60.

Obs. The image of each point of the object is located justas the point in the preceding experimentwas.

The image ofthe right eye forms the left eye of theimageofthe face.

IMAGE BY Two PLANE PARALLEL MIRRORS .

EXPERIMENT l 6 1

Obs. Several images can be seenarranged inarowatregular intervals.

IMAGE BY Two PLANE M IRRORS AT AN ANGLE.

EXPERIM ENT 1 6 2.

Obs. Three images can be seen with the mirrorsat 90degrees, fivewith themat 60degrees,and eleven with themat30degrees.

CONCAVE M IRROR.

EXPERIM ENT 1 6 3 .

Obs. The reflected rays converge, and pass th rough apoint in front of the mirror.

Focus is Latin , meaninghearth

, fireplace.

I nf . The centre of curvature is so called because it is

the centre ofasphere ofwhose surface the surface of the

mirror formsapart.



DIRECT ION or THE CHANGE.

1 . Water is denser thanair.

2. The light is bent toward the perpendicularas it entersthewater.

3 . On passing fromair (ararer) into water (adensermedium ) , ligh t is bent towardaperpendicular tothe surface separating the two media.

EXPERIMENT 1 70.

Obs. The cent is nowvisible.

Inf The light must have passed inabroken line from

the cent to the eye. On passing from the water into theair the lightwas bent from the perpendicular to the surfaceof thewater.

BY A DOUBLE—CONVEX LENS .

OF PARALLEL RAYS, PRINCIPAL Focus, FO CAL DI STANCE .

EXPERIM ENT 1 7 1 .

Obs. On leaving the lens the ligh t converges toacertainpoint,and, passing th rough it

,continuesasadiverging

pencil.

Inf. The distance Of the principal focus from the lens is

called the focal distance.

IMAGE OF AN OB JECT.

EXPERIMENT 1 72.

Obs. An inverted image larger than the Object is formedat considerable distance from the lens.

EXPER IMENT 1 7 3 .

Obs. As the candle is movedaway from the lens, the

image becomes smaller,and is formed nearer the lens.

When the image is of the same sizeas the object, theflame is twice the focal distance from the lens.

LIGHT. 243

HUMAN EYE .

(See Physiologies.)

S IMPLE M ICRO SCOPE.

The imageappears erect,and considerably larger thanthe Object.

COMPOUND M ICROSCOPE .

EXPERIM ENT 1 74 .

An inverted image much larger than the object is seen .

EXPERIMENT 1 75 .

Description sameas in Experiment 174.

REFRACTING TELESCOPE.

EXPERIM ENT 1 76 .

A small inverted image is seen .

EXPERIMENT 1 77.

A small inverted image is seen .

The refracting telescope differs from the compound micro

scope in having the Objectat considerable distance, theobject glass larger than the eye glass,and the image muchsmaller than the object, but near the eye glass. The largeobject glass takes in much more light from the objectthan the eye could,and enables us to see distant Objectsdistinctly.

REFRACTION BY A PRI SM . SOLAR SPECTRUM .

EXPERIM ENT 1 78.

A small image of the sun is formed on the screen .

EXPERIMENT 1 79.

The image is formed h igher up, is lengthened out,andhas the colors of the rainbow.


The light is bent upward on passing th rough th e prism,

thus throwing the image h igher. It must be refractedunequally, in order to lengthen the image ; and the nu

equally refracted raysare of different colors.

The colors of the spectrumare violet, blue, green , yellow,orange,and red .

I nf. 1 . The violet°

raysare refracted most.Inf. 2. The red raysare refracted least.

PRACTICAL !UESTIONS .

1 . Objects cast their longest shadows in the morningandat night, because the sun is lowerat those times.

2. They cast their shortest shadowsat noon .

3 . In the polar regions the shadowsarealways long .

4 . Within the tropics uprigh t objects cast no shadowsanoon when the sun is directlyoverhead .

5 . The half of the moon wh ich the sunlight falls on

sh ines.

6 . It does not shine upon the earth when it is directly

between the sunand the earth .

7. That portion of the lighted half of the moonwh ich isturned toward the earth atany time sh ines upon

the earth .

8. The stars sh ine by their own light.

9. Planetsare heavenly bodies wh ich revolveabout thesun in nearly circular orbits,and sh ine by the sun

’s

light,wh ile the fixed starsare outside of the solarsystem,and Sh ine by their own light.

10. (Answerswill vary. )11 . The earth Sh ineswith the sun

’s light.

12. Light from heavenlybodies in enteringand passingobliquely th rough the earth’satmosphere is con

tinually coming into denser media,and is being

refracted downward . Thus light starting froma


“ 46 ELEMENTARY LESSONS IN PHYS ICS:

PREPARATION OF OXYGEN.

EXPER IMENT 181 .

If the delivery tube were not removed from the waterbefore the flame was taken from the test tube, the gas inthe tubes would cooland contract

,and the water rush in

and break the tubes by suddenly cooling them.

PROPERTIES OF OXYGEN.

EXPERIM ENT 182.

The glowing coalbursts into flame,and burns brilliantly.

EXPER IM ENT 183 .

charcoal burns brightly, sending out sparks.

EXPERIMENT 184 .

sulphur burns faster than in theair,withabluishEXPERIM ENT 185 .

Obs. The sulphur burns,and the iron takes fireandburns with bright scintillations.

I nf. 1 . Oxygen hasastrong affinity for some other

elements.

I nf. 2. Oxides of carbon , sulphur,and iron have beenformed in these experiments.

COMBUSTION.

EXPERIMENT 186 .

Obs. Moisture (water) collects on the inside of the

chimney.

Inf. 1 . Water is produced in the burning of the candle.

Inf. 2. As it is formed by combustion , one element is

probably 0.

CHEMISTRY OB AIR AND WATER. 247

EXPERIM ENT 187.

Obs. 1 . Bubbles of colorless gas rise from the paper,andfill the bottle.

068. 2. The splinter ceases to burn,and the gas takes

fire (withaslight explosionat the mouth of the bottle)and burns withayellowish flame.

Obs. 3 . Moisture (water) forms on the inside of the bottle.

Inf. 1 . Thiswaterwas formed in the process of combus

tion .

I nf. 2. It must have been formed from oxygenand thegas which was in the bottle.

I nf. 3 . The gas came from the water wh ich was in the

bottle,as it united with O to form water.

1 . This gas is colorless, burnswith apale yellowflame(and explodeswhen mixed withair), butwoodwillnot burn in it.

I nf. 4 . Water is composed of oxygenand hydrogen .

Obs. 4 . Moisture (water) gathers on the ch imney.

Inf. 5. The oxygen comes from theair,and the hydrogenmust come from the oil or gas.

EXPER IM ENT 188.

Obs. 1 . B ubbles come from the end of the lower tube upthrough thewater.

I nf. These bubbles consist ofair.

Obs. 2. Thewater doesn’t seem to beaffected .

EXPER IM ENT 189.

Obs. 1 . The lime-water is notaffected in the first part ofthe experiment, but turns milkyin the last part.

Obs. 2. The lime-water becomes clear,andafine wh itesolid collects on the bottom of the bottle.

I nf. 1 . The coloring of the liquid was due to the smallparticles Of the wh ite substance floating in it.


Inf. 2. Two or more substances must have combined to

form th is newone.

Inf. 3 . One of these substances must have come from the

burning candle,and one must have been in the lime -water.

Inf. 4 . Thatwhich came from the candle could not havebeenwater,as therewaswater in the lime-water before,andthewhite substancewas not formed .

Inf. 5 . The substancewhich came from the candlewasagas.

EXPERIMENT 190.

Inf. 1 . The substance left in the jar cannot be oxygen .

If itwere, the charcoalwould continue to burn in it.

Inf. 2. Itwas formed from the charcoaland oxygen .

I nf. 3 . Carbon combinedwith the oxygen.

EXPERIMENT 191 .

The flame is extinguished .

EXPERIMENT 192.

The flame is extinguished.

EXPERIMENT 193 .

Obs. The lime-water turnsmilky.

I nf. 1 . Itwas carbon dioxide.

I nf. 2. Waterand carbon dioxideare formed in the burning ofacandle.

CHANGES IN AIR IN THE HUMAN BODY .

EXPERIMENT 194 .

Obs. Moisture is condensed upon the glass.

Inf. Water is given out in breath ing .

EXPER IM ENT 195 .

Obs. The lime-water becomes milky.

Inf. 1 . Carbon dioxide is given out in breathing.


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