Analog Clock History Latest

8/18/2019 Analog Clock History Latest

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Research on Analog Clock

http://around-us-facts.blogspot.com/2013/01/why-do-clocks-rotate-clockwise.html

Why do CLOCKS rotate Clockwise??

Clocks are used all over the world and wherever you go the clocks rotatein clockwise direction. This standard for the rotation of clock hands is regularly usedto refer to the direction of rotation - " Clockwise and Anticlockwise" . The explanationbelow also tells you why we celebrate New Year at Midnight.

The early watchmakers hailed from Northern Hemisphere where shadows onsundials moved West to East as the day progressed. The direction of the shadow of thesun dial is the reason for the direction of the clock.

What about the numbering system? Why the numbers are placed so?? Nowimagine the dial of your watch as Earth. The hand of the clock movesfrom West to East through Noon. During the day time, if you hold your watch upright,the HOUR hand will approximately point towards the SUN for most of the time on aSunny day.This strange way of placing the numbers on the dial has made us to celebrate NewYear and our Birthdays at mid-night.

http://www.pitara.com/science-for-kids/5ws-and-h/why-do-clocks-run-clockwise/

http://around-us-facts.blogspot.com/2013/01/why-do-clocks-rotate-clockwise.htmlhttp://around-us-facts.blogspot.com/2013/01/why-do-clocks-rotate-clockwise.htmlhttp://www.pitara.com/science-for-kids/5ws-and-h/why-do-clocks-run-clockwise/http://www.pitara.com/science-for-kids/5ws-and-h/why-do-clocks-run-clockwise/http://2.bp.blogspot.com/-FMSuHQfvgto/UPrMWGvWkdI/AAAAAAAAAv0/AZlNERhZ4nM/s1600/sundial2.jpghttp://2.bp.blogspot.com/-KNn_WyLtNbI/UPrMXYL2WkI/AAAAAAAAAv8/l-3Y6QxhfaY/s1600/earth-clocks-3.jpghttp://www.pitara.com/science-for-kids/5ws-and-h/why-do-clocks-run-clockwise/http://around-us-facts.blogspot.com/2013/01/why-do-clocks-rotate-clockwise.html


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Do you know there are some Jewish and Arabic clocks that run anti-clockwise?

This makes perfect sense as Arabic and Hebrew readers (Arabic and Hebrew

characters are written right to left) but baffles everyone else!

The clock at the bottom with the Hebrew numbers runs counterclockwise. The one on top with the Roman

numerals runs ‘clockwise’. This spire is located in the Old Jewish Town Hall in Josefov, Prague, Czech

Republic.


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HISTORY

Why do clocks usually show just a division into 12 hours when there are 24 hours in a day?

Prehistory

The origins of our 24 hour day can be traced back at least 4000 years, to ancient Egypt and

Babylon, and perhaps further back in time. The Egyptians and Babylonians divided the parade of

stars that appeared in the sky each night into 12 sections, marked by the various stars that rose

and set that night. For example, the star Procyon might rise shortly after sunset one evening,

followed about an hour later by Sirius. This defined a kind of heavenly clock, although different

groups of 12 stars were used to cope with the slow shift of the night sky during the year. Thedaylight hours were divided into 12, to match. Two sets of 12 give 24, hence the number of

hours in a day.

The famous astronomical ceiling at Senmut shows a series of circles divided into 24 sections.

It’s not clear what these circles signify – the 12 circles are labelled with month names.

Why 12? 12 is more or less the number of moon cycles in a year, so it’s a special number in

most cultures.

Sundials

1.


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Ancient Sundial , World’s Oldest Sundial , From

Egypt valley of the Kings(c. 1500 Bc).

Hemispherical Greek sundial from Ai Khanoum, Afghanistan, 3rd-2nd

century BCE.

Sundial located at the center of the Great Mosque of Kairouan(Tunisia)


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The dial of a sundial is equivalent to a 24 hour clock face. Sundials track the motion of the sun,

so noon and midnight appear directly opposite each other on the face, with 06:00 (VI) and

18:00 (VI) on either side.

Not many sundials show all 24 hour markers, though some do. This is probably for aesthetic

reasons: it makes a symmetrical design, and gives the maker something to put all round the

edge of a circle, even though half of them would never be used. The famous modern sundial

near Tower Bridge, in London, shows the full set of 24 hour marks, but you can see them on

some of the more decorative antique sundials too.

The equatorial dial on this polyhedral sundial is marked with all 24 hours (1...12, 1...12). It was

made by Hans Koch in Munich in 1578. The original is in Munich.


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Here’s an engraving from an 18th century treatise by Ferguson showing how a sundial would

look if numbered all the way round the edge.

If you ever get to spend a summer’s day at the North Pole, why not use the pole itself to make a

sundial? You’ll be able to construct a 24 hour dial, and you’ll see that the midnight and noon

marks are opposite each other. During the winter, the sun isn’t visible, however.

What did the Romans ever do for us?

The Romans inherited the 24 hour day (in the double-12 form, two sets of 1 to 12 numbers)

from the Egyptians, via the Greeks: 12 hours of daylight, followed by 12 hours of night, with

hours of variable length depending on the time of year. They started counting from sunrise

(hour 1 = Prima), so hour 3 (Tertia) was mid-morning, hour 6 (Sexta) was midday, and hour 9

(None) was midafternoon.

Echoes of this system linger today – we call a midday break a siesta, and noon is derived from

none (but may have crept forward due to hunger).


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Another Instruments about Time:

Alternative version of image:Wooden hourglass 2.jpg. Wooden hourglass. Totalheight: 25 cm. Wooden disk diameter: 11.5 cm. Running time of the hourglass: 1

hour. Hourglass in other languages: 'timglas' (Swedish), 'sanduhr' (German),

'sablier' (French), 'reloj de arena' (Spanish), 'zandloper' (Dutch),

A Candle Clock.


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Diagram of a fancy clepsydra, this type being an automaton or self-adjustingmachine. Water enters and raises the figure, which points at the current hour forthe day. Spillover water operates a series of gears that rotates a cylinder so thathour lengths are appropriate for today's date. The ancient Greeks and Romans

had twelve hours from sunrise to sunset; since summer days are longer thanwinter days, summer hours were longer than winter hours.(1819).

Arabs and astrolabes

The astrolabe was another forerunner of the clock. The Arab astronomers were adding gears to

their astrolabes by the 8th century, producing prototype clocks. As the astrolabe is a model of

the solar system, it obviously uses the 24 hour dial, rather than show two revolutions of 12

hours each per day. But given their generally better weather, they didn’t need to develop

alternatives to the astrolabe and sundial, such as water and weight-driven clocks.

Early clocks

The early history of the clock (from about 1200 to 1350 AD) is not well known, and is still

argued over by historians. None of the early clocks have survived, so we still don’t know who

invented it, or where.


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Monks and religious institutions wanted to run their services (called Prime, Tierce, Sext, None,

etc – using the Roman divisions of 1, 3, 6, 9) at regular intervals throughout the day and night,

and were looking for something better than sundials, astronomy, and water clocks, all

unreliable in cloudy and cold Northern Europe. In particular, the timing of the midnight service

proved very difficult. Hence the intense interest in making a mechanical clock.

We can guess that the first clocks didn’t even have dials – they were probably just devices for

ringing bells at regular intervals. (The word ‘clock’ means bell.) Bells were used for relaying

information around churches and monasteries, and in towns and cities. Bells signaled the times

of services, the start and end of work shifts, the opening of markets, the start of meetings,

court events, trials and executions, and so on, and would have used combinations and special

sequences to indicate messages. So a device for automating the ringing of bells eventually led

To the development and rapid introduction of a generalized time-measuring system, and

machines for keeping it.

And behind all this practical need for machines and systems to keep religious and secular life

punctual was a desire to look upwards and emulate something of the spectacular display of the

sun, moon, planets, and stars, to inspire the religious spirits.

One of the earliest mentions of a clock-like machine was in 1271, when Robertus Anglicus

wrote that:

Clockmakers are trying to make a wheel that will move exactly as the motion of the equinoctial

circle


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So a wheel that revolved once every 24 hours was the obvious solution for a device that not

only kept the time, day and night, but echoed the religious view of the universe, where the

heavens revolve in a God-given orderly procession around the earth.

Nearly 100 years later, the clockmakers had succeeded, since the great Italian clockmaker DeDondi could quickly gloss over the mechanics of the 24 hour clock when he writes about his

astronomical clock:

but the method of making this clock will not be discussed in such detail as the rest because its

construction is well known, and there are many varieties of them, and however it is made the

diversity of methods does not come within the scope of this work since we desire nothing more

from it [the clock at the center of his planetarium] than the uniform and equal motion of a

wheel which shall complete its course in the space of a natural day, and such a wheel is called

the horary sphere.

Planetarium

From about 1300 on, clocks developed quickly along two main paths. In towns, the public or

church clock became a common sight (and sound), ordering and marking the passing of the

hours of day and night. When dials were eventually introduced, they would be 24 hour ones,

although few have survived in their original form, so we can’t be sure.

Other clocks developed into sophisticated planetaria: Richard of Wallingford’s famous

astronomical clock, which he built over a course of 30 years at St Albans starting in 1330, and

Giovanni de Dondi’s clock, completed in 1364, were both mechanical marvels, calculating moon

and planetary orbits, and even eclipses. These had 24 hour dials, showing the sun and earth’s

relative motions during the day and night in graphic form.

The clock at Wells Cathedral dates from the end of the 14 century, although the dial is probably

later.


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Non-standard time

Timekeeping methods varied from country to country. In Italy, they counted their hours from

sunset, so by sunrise in the morning the hour was already about 12 or 13. The 1 to 24

numbering system used in Italy was known in France, Germany, and England as Italian Hours.

The northern Europeans often divided the 24 hours up into two sets of 1 to 12, probably

arranged so that 12 noon is at the top of the dial, and 12 midnight at the bottom. Notice how

the Wells dial, above, doesn’t actually use the Roman numeral XII for either.

The famous clock of the Beata Vergine (later San Gottardo) in Milan, built around 1330, was one

of the earliest to strike a bell a number of times to tell the time (not just striking once on the

hour). In 1335, Galvano Fiamma writes:

There is there a wonderful clock, because there is a very large clapper which strikes a bell 24

times according to the 24 hours of the day and night, and thus at the first hour of the night

gives one sound, at the second two strokes, and so distinguishes one hour from another, which

is of greatest use to men of every degree.

By contrast, the French and Northern Europeans were using the 24 hour double-XII dial, and

were also introducing the single 12 hour dial. The 12 hour system was known as German hours

in Bohemia, and French hours in Italy. Clocks imported into Italy were often converted from

French-style numbering to use the 24 hour Italian system. In Southern Germany (Augsburg),

which became one of the main Centre’s of clock making by the 15th century, clockmakers were

making clocks with both 12 hour and 24 hour dials, sometimes with both on the same clock.

They used the terms ‘great’ and ‘small’ time systems to refer to the 24 and 12 hour time


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systems. This German alarm clock from the 1500s has three rings, each showing Arabic rather

than Roman numerals:

When did the roman-style counting (starting from dawn with 1) give way to our modern style

counting, starting at midnight (or midday) with 0? Perhaps when clocks were regularly

synchronized with the sun. Noon/midday is the easiest and most accurate way of synchronizing

clocks with solar time, the basis for time until clocks were accurate enough to track the Earth’s

irregularities.

Why the move to 12 hour time?

Both the 24 hour time system (1 to 24, as used in Italy) and the double-XII system (1 to 12 then

1 to 12 again, as used in England and Northern Europe) can be displayed on a 24 hour dial. So

why did the 12 hour dial, with the added ambiguity of AM and PM, become popular and

eventually dominate, for general-purpose public clocks, at least, between 1400 and 1600?

Here are some suggestions:

REASON ARGUMENTS OBJECTIONS

power needed

to ring bell

Ringing a bell up to 24 times uses up a lot of

power (up to twice as much as ringing the

bell 12 times!), and reduces the period

between windings. The 12 hour dial reduced

A double-XII dial could have had

matching bell ringing sequences (1 to 12,

then 1 to 12) but still displayed on a 24

hour dial. Why change a familiar dial?

https://24hourtime.files.wordpress.com/2009/04/l1040335.jpg


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the amount of power required to ring the

bell on the hour. Also, portable spring-driven

clocks – and later watches – were the latest

thing, and the power savings gained by the

12 hour dial were eagerly seized by the

clockmakers. Italy eventually followed otherEuropean countries, which had started

switching to the 12 hour clock by 1550.

lose count of

24 strokes

It’s been suggested is that people lost count

while listening to a long run of up to 24 bells.

So the switch to 12 made it easier to tell the

time

Clock makers would have introduced

some form of code (one bell rings before

12, another bell rings from 12 to 24, for

example) if they had had the power to

spare. Besides, counting bells isn’t that

difficult, really. 4 year old children can

do it. Although it’s easy to lose count if

you’re in a noisy environment.

too difficult to

read

A 24 hour dial squeezes in 6 hours between

what the 12 hour dial shows as 0900 and

1200 – so it’s difficult to tell the difference

between, say, 10 and 11, because they’re

closer together. This is particularly true

before minute hands were widely used

(before about 1650?) People are looking at a

tower clock from some distance too, and

upwards – it would be much easier for a 12

hour dial (or even a 6 hour dial).

It would depend on the design, partly,

and the way the dial was numbered. And

‘difficult’ is very subjective: we now

learn the 12 hour dial intensively when

young, so how do we know whether 24

hour dials are really harder to read? Do

we find minutes hard to read – they’ve

got 60 divisions?

shows up

inaccurate

clocks too

quickly

A 24 hour dial increases the required

precision for the hour hand, because the

hour hand moves less during an hour: if it’s

not accurate, it will soon start to be slower or

faster. On a 12 hour dial with the same

works, it takes twice as long to look like it’s

an hour adrift.

An ingenious but not entirely convincing

argument!

not enough

resolution for

accurate time

keeping

With more hours squeezed into a smaller arc,

it was harder to read the exact time from a

single hand on the 24 hour dial than on the

12 hour dial. This was before the widespread

introduction of the minute hand, of course,

so the difference between half past 10 and a

quarter past ten would be harder to discern

This is a more convincing version of the

above argument. But I’m not sure if the

dates for the introduction of the minute

hand and the growing popularity of the

12 hour dial coincide, though. Anyway,

no clocks were really accurate (to a


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on a 24 hour dial, unless the radius of the dial

was very big.

minute or so) before the introduction of

the pendulum in about 1650.

dominance of

one country

forced othersto adapt

The clockmakers of France and, to some

extent, Germany tended to use the 12 hour

dial more than the 24 hour dial, and thetechnical superiority of their clocks forced

out the less efficient makers of clocks with 24

hour dials, such as Italy. The gradual drift

northward of the power Centre’s of Europe

during the renaissance is well documented.

This is plausible. But is it true? And what

about English clockmakers?

avoids

duplication so

quicker to

make

The urge to simplify complexity and thereby

reduce work and hopefully improve accuracy

led clockmakers to eliminate the duplicate

dial numbers and rely on context to resolve

the ambiguity. There are other examples ofsimilar attempts: the six hour dial, Benjamin

Franklin’s 8 hour dial, and so on.

This theory suggests that clockmakers

are the type of people who would just

hate to have unnecessary duplication,

even if it was merely the numbering on

the dial. Making life easier fordevelopers and harder for users has a

very modern ring to it.

24 hour time

became

Italian-only

Italians were counting from sunset with their

1-24 system, and the Northern Europeans

were counting from midnight with their

double-XII systems. Perhaps the 24 hour dial

became associated with sunset-starting

clocks, so the 12 hour dial became the

standard for midnight-starting clocks (which

eventually became the standard).

This links in with the Northern-drift

theory of the renaissance above, which

may be true.

I don’t suppose we’ll ever know for sure!

17th Century: Tompion, Harrison, and Mudge

Gradually the 12 hour dial became used for most standard clocks, and the 24 hour dial was

reserved for the more esoteric, technical, or complex clocks. The famous clockmakers were

happy to design both 12 and 24 hour dials according to need or preference. The big

astronomical clocks, such as those to be found at Prague or Strasbourg, usually used the 24

hour dial, with Arabic numerals from 1 to 24 for the Italian hours and Roman numerals

(double-XII) for the North European numbering.


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Thomas Tompion built some long case clocks with 24 hour dials, which you can see in

museums today. Tompion has been called the father of English clock making, and is sometimes

reckoned to be one of the greatest craftsmen of all time. This ‘Equation Clock’ was built in

1695 for King William III. As well as the double-XII hour dial, it has a double-60 minute dial –

the minute hand makes one revolution every two minutes. There’s also an outer minute ring

which rotates back and forward to show apparent solar time. So you could read off the

difference between mean time and local solar time by comparing the minute rings.


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Tompion also built this Astrolabe clock in 1677:

You can see the sun and moon hands, and the moon phase in the central disk, next to the

astrological graphics.


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Tompion and George Graham collaborated to make this orrery (a working model of the solar

system), which naturally used the 24 hour dial on the side.

It’s interesting to compare this idea with the older church clocks, which are of ten described as

illustrating the Ptolemaic – earth-centred – view of the solar system. The orrery shows the

Copernican view – but even in an Einsteinian view of the universe, a terrestrial rotation

simulator would probably have a 24 hour dial. The original is in the Museum of History of

Science in Oxford.

John Harrison (famous clockmaker and star of the best-selling book Longitude) used the 24

hour dial for his first chronometer H1, built in about 1730.


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Harrison’s H1 chronometer. Read more about Harrison’s clocks at The Royal Observatory

Greenwich site.

This is the hour dial of H1.

Following Harrison, Thomas Mudge designed three marine chronometers, this one with a 24

hour dial.

A feature of this is that the hour dial has two scales: one for the hours (1-12/1-12), then,

inside, degrees in 15 degree steps from 0 to 360. This presumably allows some kind of


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conversion from hours (time) to degrees (longitude). (The fourth dial at the top indicates how

much the clock is wound up.) This example is in the British Museum.

Often, it was the professional time-users – astronomers, navigators, for example – who used

the 24 hour dial, and, sometimes the 24 hour time system as well. For example, the log bookfor Captain Cook’s second voyage – during which he tested various clocks that would help find

the longitude – shows handwritten entries that use the 24 hour time system, so switching

between 24 and 12 hour dials wouldn’t have been a problem for them. In fact, anyone working

with time needed to have their wits about them.

Confusion

In general, there was much less standardization of time and clocks than today, and – probably –

much confusion, not just with time zones, but with time systems too.

For astronomers, the day started at noon (easy to measure the sun’s position), so they counted

their hours from noon. This was still the case up to 1925, although the civil day continued to

end at midnight. For navigators at sea, however, the day ended at noon. At 6 o’clock on Monday

morning civil time, it was 18:00 on Sunday for astronomers. 12 hours later, at 6 o’clock in the

evening on Monday, civil time, it was 6pm on Tuesday for the navigator, but 06.00 on Monday

for the astronomer. When a ship entered harbour, the navigator switched from nautical time to

civil time. Captain Cook and his astronomer William Wales recorded the same time in different

ways, and switched when they entered harbour.

A gallery of old clocks and watches

In the 18th and 19th centuries, makers continued to build a wonderful variety of timepieces,

and a substantial minority of them had 24 hour dials. Some of these clocks were built as

‘exhibition’ clocks, to be taken on tour round the country and displayed to the wondering

public for a small entry fee. Here is a small selection of 24 hour analog clocks and watches.

This is one side of a two-sided watch – the other side is a conventional 12 hour dial. Perhaps

the owner was intending to travel across Europe, switching between 12 hour and 24 hour dials

as needed.


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Around the edge of the 24 hour dial are the signs of the zodiac and a month hand – the other

side shows the day of the month (1 to 31). It was made by David Pons, England, in 1770.

This is one of the monumental showpiece clocks. It’s an astronomical organ clock by Henry

Jenkins (1770):


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While the curious observer sits at the hinged bureau flap thoughtfully provided to support his

notebook, the organ beguiles him with a selection of twelve tunes.

The clock shows details of the moon, high tide times, lengths of the day and night, and

includes a map of the world and the stars.

The map probably rotates around the Centre, thus showing the time in any location on the

earth. The counterclockwise numbering reminds us that the earth does in fact rotate in that

direction, rather than clockwise.


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This extravagant table clock was made by Peter Klein in Dresden about 1738:


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The globe in the Centre rotates once a day, like the earth, and moves the pointer around the

clock, with the North Pole facing outwards. There’s also a glass shade that darkens the areas of

the earth that are currently experiencing darkness.

Here is an overgrown watch doubling as a ship’s chronometer:

It was made by George Margetts in about 1780. At the center is a 12 hour dial with the names

of 8 English ports; the 24 hour dial shows the times of low and high tide. This watch also

manages to show the moon’s position in the zodiac, its declination, its latitude, its ecliptic

nodes, its age, as well as eclipses of the sun and moon, the date, sun’s declination, twilight

period, sun’s position in the zodiac. It apparently has only 16 gears. It might be in the National

Maritime Museum at Greenwich.

At the other extreme, here’s a Swiss watch, made in 1880, recently on sale

athttp://www.antique-watch.com/:

http://www.antique-watch.com/http://www.antique-watch.com/http://www.antique-watch.com/http://www.antique-watch.com/


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In this design midnight is marked as ’24’, rather than ‘0’. Also, the minutes start with 0 at the

bottom of the dial, rather than at the top.

This watch was made by John Johnson of Preston, England, in 1868:

It has Harrison’s Maintaining Power (which means that it keeps going while you’re winding it)

and Bossley regulation. It was recently on sale at Robert Young’s Pocket Watch shop. From

midnight to noon is numbered in Roman numerals, and from noon to midnight in Arabic. Notice

that this watch puts midnight on the top, whereas the previous one put noon at the top.


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This unusual 10 inch high spherical skeleton clock was made in about 1760. It just makes this

web site because it has a spherical band with the 24 hour numbers:

During the 19th century, the 24 hour dial was being used for more earthly reasons, rather than

with the astronomical and religious intentions of the early clock makers. The ability of the 24

hour dial to display a wide range of times up to a day apart made it useful for showing the time

in different parts of the world, and this use started to become important.

This extravagant French clock made in 1856 has 13 dials, the lower 8 of which are 24 hour

dials, showing the time in London, New York, St Petersburg, Canton, Tahiti, Alexandria, Algiers,

and St Helena:


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The bottom half of each 24 hour dial has a dark border, to indicate night time. The other dials

show the equation of time (for use with sundials), month/days of the week, and phases of the

moon (and the time in 12 hour system). It makes you wonder: why would a clock owner in 1856

want to know the exact time in Jakarta or Johannesburg in 1850 – before the introduction oftelephones or radio?

This is a late 19th century sidereal clock, which tells the time according to the stars:

A sidereal day is about 4 minutes shorter than the solar day. They were of most use in

observatories. This one can be found in the Norman Lockyer Observatory in Devon.

In 1852, this 24 hour clock was installed outside the Royal Observatory at Greenwich, London:


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It was the first clock to make Greenwich Time available to the public. The master clock

(installed inside the observatory) controlled this one by remote control and electric wires. It says

about 16:19 (or, in 12-hour speak, 4 o’clock Post Meridiem plus 19 minutes), and midnight is

at the top. The Roman numerals aren’t very readable to a modern eye.

The Modern era

In the 20th century, new groups encouraged the manufacture of 24 hour clocks. Radio

enthusiasts needed to know the time around the world, and often adopted the 24 hour dial. Themilitary wanted unambiguous times and adopted the 24 hour time system already widely used

in Europe, encouraging the construction of 24 hour analog clocks and watches.

Pilots – already confident in reading a wide assortment of unusual dials – adopted the 24 hour

dial for clocks in cockpits, and for their watches too. Here are a few mechanical cockpit clocks

(collected by tgarn on the 24 hour watches forum).


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This is the Willis World clock from the 1930s, seen in the London Science Museum.


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New and not so new 24 hour clocks and watches from the 20th century still turn up today. Here

are some of the clocks I’ve seen on sale on the net recently. EBay is always a good place to look.

All these examples put midnight at the top, by the way – it’s become the standard.

This clock includes various cities of the world in the middle:

The map disk on this Master Crafters clock rotates manually. You typically set the clock to read

GMT and then adjust the disk to show the correct time in your time zone:

https://24hourtime.files.wordpress.com/2009/04/l1040330.jpg


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Bakelite clocks are very collectable. This US Military clock with its functional design reminds me

of modern central heating controllers:

Here’s another US military clock:


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The future

Today, although the 12 hour dial is standard; the 24 hour analog dial is used by the specialist

and the connoisseur, and sought after by the individual and the collector. Kids struggle for

years to learn how to tell the time using the 12 hour dial, and would probably find the 24 hour

analog dial and 24 hour time system much more logical.

24 hour analog clocks and watches are still being made, and are highly sought after.

I’ve seen them used just once in computer user interfaces. It provides an elegant and simple

graphical way of selecting a time, which is not so easy to do on a 12 hour dial, because of the

AM/PM issue. About ten years ago, there was an application called Web Arranger. This was a

new kind of application that organized and integrated your web browsing and personal

information. Web Arranger was made by CE Software, who discontinued it in about 1996, I

think. The widget for selecting a time used a double-12 analog dial, with the evening half

colored black:

The Long Now foundation are thinking hard about the future. Will their clock have a 12 hour or

24 hour dial?


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There’s no shortage of other ideas for radical changes in the way we keep, measure, and

display time, but I believe that the logical and elegant 24 hour dial will be with us for many

years to come. So why not make your next clock or watch a real 24 hour one?

Further reading

Here are some books on the development of clocks that you might be interested in.

History of the Hour: Clocks and modern temporal orders: Gerhard Dohen van Rossum this is a

study of the development of clocks and the development of modern time-keeping practices

from Roman times to today. While a bit dry and scholarly at times (it’s translated from the

German), it’s a great introduction to a fascinating subject.

Revolution in Time: Clocks and the making of the modern world David Landes

This is a very readable account of the history of timekeeping written by an economic historian.

At times he’s more interested in the economic aspects of clock and watch manufacturing than I

felt I wanted to be, but it’s a good read.

A history of clocks and watches Eric Bruton


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An extremely well-illustrated general survey of clocks and watches, back in print. Buy it for the

pictures, then read the text!

Greenwich Time and the discovery of the longitude Derek Howse

This tells the history of confusing time systems, and the gradual standardization in the 18th

and 19th centuries. There’s a lot of information about the introduction of Greenwich Time, and

amusing descriptions of the bureaucratic proceedings as every faction tried hard not to give

anything away. (“Legal time in France is Paris Mean Time, retarded by 9 minutes 21 seconds” –

the French in 1898, trying hard to avoid mentioning Greenwich.)

http://www.units.miamioh.edu/dragonfly/time/egypt.shtml

The Sumerian culture was lost without passing on its knowledge of time. The

Egyptians were the next group of people to divide their day into parts, similar to ourhours. About 3500 B.C., Egyptians created a slender four-sided tapering monument

called an obelisk, which cast shadows. By looking at the obelisk's shadows, people

could tell when noon occurred and, thus, divide their day into two parts. Later, the

Egyptians added markers around the base of the obelisk to indicate more divisions of

time throughout the day. These divisions are similar to our hours.

Another shadow clock or sundial came into use around 1500 B.C. to measure the

passage of "hours." This clock was oriented east and west in the morning. An elevated

crossbar cast a moving shadow on the "hour" markers. At midday, Egyptians turned

the device in the opposite direction to measure the afternoon "hours."

http://www.units.miamioh.edu/dragonfly/time/egypt.shtmlhttp://www.units.miamioh.edu/dragonfly/time/egypt.shtmlhttp://www.units.miamioh.edu/dragonfly/time/egypt.shtml


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The ancient Egyptians even learned to keep track of time at night. An instrument

called a merkhet was developed in 600 B.C. It is the oldest known astrometrical tool,

which is a tool to measure the positions, movements and distances of planets and

stars. Egyptians lined up a pair of merkhets with a certain star, called the Pole Star, to

establish a north-south line. The Egyptians used the merkhets to mark off nighttimehours by determining when other stars crossed the meridian. Not bad for a people

living 2,600 years ago!

Thank you for your Interest.

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