MODERN CLOCKS
DeVick's clock of 1364. -- Original "verge" escapement. --
"Anchor" and "dead beat" escapements. -- "Remontoir" clock.
-- The pendulum. -- Jeweling pallets. -- Antique clock with
earliest application of pendulum. -- Turkish watches. -- Correct
designs for public clock faces. -- Art work on old watches. --
Twenty-four hour watch. -- Syrian and Hebrew hour numerals. --
Correct method of striking hours and quarters. -- Design for
twenty-four hour dial and hands. -- Curious clocks. -- Inventions
of the old clockmakers.
[Illustration: Public Dial by James Arthur Dial of Philadelphia City
Hall Clock
Fig. 24]
Modern clocks commence with De Vick's of 1364 which is the first
unquestioned clock consisting of toothed wheels and containing the
fundamental features of our present clocks. References are often
quoted back to about 1000 A. D., but the words translated "clocks"
were used for bells and dials at that date; so we are forced to
consider the De Vick clock as the first till more evidence is
obtained. It has been pointed out, however, that this clock could
hardly have been invented all at once; and therefore it is probable
that many inventions leading up to it have been lost to history. The
part of a clock which does the ticking is called the "escapement"
and the oldest form known is the "verge," Fig. 25, the date of which
is unknown, but safely 300 years before De Vick. The "foliot" is on
the vertical verge, or spindle, which has the pallets A B. As the
foliot swings horizontally, from rest to rest, we hear one tick, but
it requires two of these single swings, or two ticks, to liberate
one tooth of the escape wheel; so there are twice as many ticks
in one turn of the escape wheel as it has teeth. We thus see that
an escapement is a device in which something moves back and forth
and allows the teeth of an "escape wheel" to escape. While this
escapement is, in some respects, the simplest one, it has always
been difficult to make it plain in a drawing, so I have made an
effort to explain it by making the side of the wheel and its pallet
B, which is nearest the eye, solid black, and farther side and its
pallet A, shaded as in the figure. The wheel moves in the direction
of the arrow, and tooth D is very near escaping from pallet B. The
tooth C on the farther side of wheel is moving left, so it will fall
on pallet A, to be in its turn liberated as the pallets and foliot
swing back and forth. It is easy to see that each tooth of the wheel
will give a little push to the pallet as it escapes, and thus keep
the balance swinging. This escapement is a very poor time-keeper,
but it was one of the great inventions and held the field for about
600 years, that is, from the days when it regulated bells up to the
"onion" watches of our grandfathers. Scattered references in old
writings make it reasonably certain that from about 1,000 to 1,300
bells were struck by machines regulated with this verge escapement,
thus showing that the striking part of a clock is older than the
clock itself. It seems strange to us to say that many of the earlier
clocks were strikers, only, and had no dials or hands, just as if
you turned the face of your clock to the wall and depended on the
striking for the time. Keeping this action of the verge escapement
in mind we can easily understand its application, as made by De
Vick, in Fig. 26, where I have marked the same pallets A B. A tooth
is just escaping from pallet B and then one on the other side of
the wheel will fall on pallet A. Foliot, verge and pallets form one
solid piece which is suspended by a cord, so as to enable it to
swing with little friction. For the purpose of making the motions
very plain I have left out the dial and framework from the drawing.
The wheel marked "twelve hours," and the pinion which drives it, are
both outside the frame, just under the dial, and are drawn in dash
and dot. The axle of this twelve-hour wheel goes through the dial
and carries the hand, which marks hours only. The winding pinion and
wheel, in dotted lines, are inside the frame. Now follow the "great
wheel"--"intermediate"--"escape wheel" and the two pinions, all in
solid lines, and you have the "train" which is the principal part
of all clocks. This clock has an escapement, wheels, pinions, dial,
hand, weight, and winding square. We have only added the pendulum,
a better escapement, the minute and second hands in over 500 years!
The "anchor" escapement, Fig. 27, came about 1680 and is attributed
to Dr. Hooke, an Englishman. It gets its name from the resemblance of
the pallets to the flukes of an anchor. This anchor is connected to
the pendulum and as it swings right and left, the teeth of the escape
wheel are liberated, one tooth for each two swings from rest to rest,
the little push on the pallets A B, as the teeth escape, keeping the
pendulum going. It is astonishing how many, even among the educated,
think that the pendulum drives the clock! The pendulum must always be
driven by some power.
[Illustration: Fig. 25--Verge Escapement]
[Illustration: Fig. 26--De Vick's Clock of 1364]
[Illustration: Fig. 27--Anchor Escapement]
[Illustration: Fig. 28--American Anchor Escapement]
This escapement will be found in nearly all the grandfather clocks in
connection with a seconds pendulum. It is a good time-keeper, runs
well, wears well, stands some rough handling and will keep going
even when pretty well covered with dust and cobwebs; so it is used
more than all the numerous types ever invented. Figure 28 gives the
general American form of the "anchor" which is made by bending a
strip of steel; but it is not the best form, as the acting surfaces
of the pallets are straight. It is, therefore, inferior to Fig. 27
where the acting surfaces are curved, since these curves give an
easier "recoil." This recoil is the slight motion _backwards_ which
the escape wheel makes at each tick. The "dead beat" escapement is
shown in Fig. 29, and is used in clocks of a high grade, generally
with a seconds pendulum. It has no recoil as you can easily see that
the surfaces O O on which the teeth fall, are portions of a circle
around the center P. The beveled ends of these pallets are called the
impulse surfaces, and a tooth is just giving the little push on the
right-hand pallet. It is found in good railroad clocks, watch-makers'
regulators and in many astronomical clocks. These terms are merely
comparative, a "regulator" being a good clock and an "astronomical,"
an extra good one. Figure 30 gives the movement of a "remontoir"
clock in which the dead beat shown is used. The upper one of the
three dials indicates seconds, and the lever which crosses its center
carries the large wheel on the left.
[Illustration: Fig. 29--Dead Beat Escapement]
[Illustration: Fig. 31--Remontoir Clock by James Arthur]
[Illustration: Fig. 30--Remontoir Clock Movement]
This wheel makes the left end of the lever heavier than the right,
and in sinking it drives the clock for one minute, but at the
sixtieth second it "remounts" by the action of the clock weight;
hence the name, "remontoir." Note here that the big weight does
not directly drive the clock; it only rewinds it every minute. The
minutes are shown on the dial to the right and its hand jumps forward
one minute at each sixtieth second as the lever remounts; so if you
wish to set your watch to this clock the proper way is to set it to
the even minute "on the jump." The hour hand is on the dial to the
left. By this remounting, or rewinding, the clock receives the same
amount of driving force each minute. The complete clock is shown
in Fig. 31, the large weight which does the rewinding each minute
being plainly visible. The pendulum is compensated with steel and
aluminum, so that the rate of the clock may not be influenced by hot
and cold weather. Was built in 1901 and is the only one I can find
room for here. It is fully described in "Machinery," New York, for
Nov., 1901. I have built a considerable number, all for experimental
purposes, several of them much more complicated than this one, but
all differing from clocks for commercial purposes. Pallets like O
O in Fig. 29 are often made of jewels; in one clock I used agates
and in another, running thirteen months with one winding, I used
pallets jeweled with diamonds. This is done to avoid friction and
wear. Those interested in the improvement of clocks are constantly
striving after light action and small driving weights. Conversely,
the inferior clock has a heavy weight and ticks loud. The "gravity
escapement" and others giving a "free" pendulum action would require
too much space here, so we must be satisfied with the few successful
ones shown out of hundreds of inventions, dozens of them patented.
The pendulum stands at the top as a time measurer and was known to
the ancients for measuring short periods of time just as musicians
now use the metronome to get regular beats. Galileo is credited with
noticing its regular beats, but did not apply it to clocks, although
his son made a partially successful attempt. The first mathematical
investigation of the pendulum was made by Huyghens about 1670, and
he is generally credited with applying it to clocks, so there is a
"Huyghens" clock with a pendulum instead of the foliot of De Vick's.
Mathematically, the longer and heavier the pendulum the better is
the time-keeping, but nature does not permit us to carry anything to
the extreme; so the difficulty of finding a tower high enough and
steady enough, the cumbersomeness of weight, the elasticity of the
rod, and many other difficulties render very long and heavy pendulums
impracticable beyond about 13 ft. which beats once in two seconds.
"Big Ben" of Westminster, London, has one of this length weighing 700
lb. and measuring, over all, 15 ft.
It runs with an error under one second a week. This is surpassed
only by some of the astronomical clocks which run sometimes two
months within a second. This wonderful timekeeping is done with
seconds pendulums of about 39 in., so the theoretical advantage of
long pendulums is lost in the difficulties of constructing them.
Fractions are left out of these lengths as they would only confuse
the explanations. At the Naval observatory in Washington, D. C.,
the standard clocks have seconds pendulums, the rods of which are
nickel steel, called "Invar," which is little influenced by changes
of temperature. These clocks are kept in a special basement, so
they stand on the solid earth. The clock room is kept at a nearly
uniform temperature and each clock is in a glass cylinder exhausted
to about half an atmosphere. They are electric remontoirs, so no
winding is necessary and they can be kept sealed up tight in their
glass cylinders. Nor is any adjustment of their pendulums necessary,
or setting of the hands, as the correction of their small variations
is effected by slight changes in the air pressure within the glass
cylinders. When a clock runs fast they let a little air into its
cylinder to raise the resistance to the pendulum and slow it down,
and the reverse for slow. Don't forget that we are now considering
variations of less than a second a week.
The clock room has double doors, so the outer one can be shut before
the inner one is opened, to avoid air currents. Visitors are not
permitted to see these clocks because the less the doors are opened
the better; but the Commander will sometimes issue a special permit
and detail a responsible assistant to show them, so if you wish
to see them you must prove to him that you have a head above your
shoulders and are worthy of such a great favor.
[Illustration: Fig. 32--Antique Clock, Entirely Hand-Made]
[Illustration: Fig. 33--Antique Clock, Entirely Hand-Made]
[Illustration: Fig. 34--Triple-Case Turkish Watches]
The best thing the young student could do at this point would be
to grasp the remarkable fact that the clock is not an old machine,
since it covers only the comparatively short period from 1364 to the
present day. Compared with the period of man's history and inventions
it is of yesterday. Strictly speaking, as we use the word clock, its
age from De Vick to the modern astronomical is only about 540 years.
If we take the year 1660, we find that it represents the center of
modern improvements in clocks, a few years before and after that date
includes the pendulum, the anchor and dead beat escapements, the
minute and second hands, the circular balance and the hair spring,
along with minor improvements. Since the end of that period, which
we may make 1700, no fundamental invention has been added to clocks
and watches. This becomes impressive when we remember that the last
200 years have produced more inventions than all previous known
history--but only minor improvements in clocks! The application
of electricity for winding, driving, or regulating clocks is not
fundamental, for the timekeeping is done by the master clock with
its pendulum and wheels, just as by any grandfather's clock 200
years old. This broad survey of time measuring does not permit us to
go into minute mechanical details. Those wishing to follow up the
subject would require a large "horological library"--and Dr. Eliot's
five-foot shelf would be altogether too short to hold the books.
A good idea of the old church clocks may be obtained from Fig.
32 which is one of my valued antiques. Tradition has followed it
down as the "English Blacksmith's Clock." It has the very earliest
application of the pendulum. The pendulum, which I have marked by a
star to enable the reader to find it, is less than 3 in. long and
is hung on the verge, or pallet axle, and beats 222 per minute.
This clock may be safely put at 250 years old, and contains nothing
invented since that date. Wheels are cast brass and all teeth
laboriously filed out by hand. Pinions are solid with the axles, or
"staffs," and also filed out by hand. It is put together, generally
by mortise, tenon and cotter, but it has four original screws all
made by hand with the file. How did he thread the holes for these
screws? Probably made a tap by hand as he made the screws. But the
most remarkable feature is the fact that no lathe was used in forming
any part--all staffs, pinions and pivots being filed by hand. This is
simply extraordinary when it is pointed out that a little dead center
lathe is the simplest machine in the world, and he could have made
one in less than a day and saved himself weeks of hard labor. It is
probable that he had great skill in hand work and that learning to
use a lathe would have been a great and tedious effort for him. So we
have a complete striking clock made by a man so poor that he had only
his anvil, hammer and file. The weights are hung on cords as thick
as an ordinary lead pencil and pass over pulleys having spikes set
around them to prevent the cords from slipping. The weights descend
7 ft. in 12 hours, so they must be pulled up--not wound up--twice a
day. The single hour hand is a work of art and is cut through like
lace. Public clocks may still be seen in Europe with only one hand.
Many have been puzzled by finding that old, rudely made clocks often
have fine dials, but this is not remarkable when we state that art
and engraving had reached a high level before the days of clocks.
It is worthy of note that clocks in the early days were generally
built in the form of a church tower with the bell under the dome
and Figs. 32, 33 show a good example. It is highly probable that the
maker of this clock had access to some old church clock--a wonderful
machine in those days--and that he laboriously copied it. It strikes
the hours, only, by the old "count wheel" or "locking plate" method.
Between this and our modern clocks appeared a type showing quarter
hours on a small dial under the hour dial. No doubt this was at that
time a great advance and looked like cutting time up pretty fine. As
the hand on the quarter dial made the circuit in an hour the next
step was easy, by simply dividing the circle of quarters into sixty
minutes. The old fellows who thought in hours must have given it up
at this point, so the seconds and fifths seconds came easily.
[Illustration: Fig. 35--Triple-Case Turkish Watch]
[Illustration: Fig. 36--Double-Case Watch of Repoussé Work]
The first watches, about 1500, had the foliot and verge escapement,
and in some early attempts to govern the foliot a hog's bristle was
used as a spring. By putting a ring around the ends of the foliot
and adding the hair spring of Dr. Hooke, about 1640, we have the
verge watches of our grandfathers. This balance wheel and hair spring
stand today, but the "lever" escapement has taken the place of the
verge. It is a modification of the dead beat, Fig. 29, by adding
a lever to the anchor, and this lever is acted on by the balance,
hence the name "lever watch." All this you can see by opening your
watch, so no detailed explanation is necessary. Figure 34 shows two
triple-cased Turkish watches with verge escapements, the one to the
left being shown partly opened in Fig. 35. The watch with its inner
case, including the glass, is shown to the right. This inner case
is complete with two hinges and has a winding hole in the back. The
upper case, of "chased" work, goes on next, and then the third, or
outer case, covered with tortoise shell fastened with silver rivets,
goes on outside the other two. When all three cases are opened and
laid on the table, they look like a heap of oyster shells, but they
go easily together, forming the grand and dignified watch shown to
the left in Fig. 34. Oliver Cromwell wore an immense triple-case
watch of this kind, and the poor plebeians who were permitted to
examine such a magnificent instrument were favored!
[Illustration: Fig. 37--Watches Showing Art Work]
[Illustration: Fig. 38--Watch Showing Dutch Art Work]
[Illustration: Fig. 39--Antique Watch Cock]
[Illustration: Fig. 40--"Chinese" Watch]
Our boys' watches costing one dollar keep much better time than this
type of watch. Comparing the Syrian dial, Fig. 42, with that on
Fig. 35, it is evident that the strange hour numerals on both are a
variation of the same characters. These, so-called, "Turkish watches"
were made in Europe for the Eastern trade. First-class samples of
this triple-case type are getting scarce, but I have found four, two
of them in Constantinople. Figure 36 shows the double-case style,
called "pair cases," the outer case thin silver, the figures and
ornaments being hammered and punched up from the inside and called
"repoussé." Before we leave the old watches, the question of art work
deserves notice, for it looks as if ornamentation and time-keeping
varied inversely in those days--the more art the worse the watch. I
presume, as they could not make a good time-keeper at that date, the
watch-maker decided to give the buyer something of great size and
style for his money. In Fig. 37 four old movements are shown, and
there is no doubt about the art, since the work is purely individual
and no dies or templates used. In examining a large number of these
watches, I have never found the art work on any two of them alike.
Note the grotesque faces in these, and in Fig. 39 which is a fine
example of pierced, engraved work. Figure 38 is a fine example of
pierced work with animals and flowers carved in relief. Figure 40
is a "Chinese" watch but made in Europe for the Chinese market. In
Fig. 41 we have what remains of a quarter repeater with musical
attachment. Each of the 24 straight gongs, commencing with the
longest one, goes a little nearer the center of the large wheel,
so a circle of pins is set in the wheel for each gong, or note,
and there is plenty of room for several tunes which the wearer can
set off at pleasure. Figure 43 is a modern watch with Hebrew hour
numerals. Figure 44 is a modern 24-hour watch used on some railroads
and steamship lines. I have a pretty clean-cut recollection of one
event in connection with the 24-hour system, as I left Messina
between 18 and 19 o'clock on the night of the earthquake! Dials and
hands constitute an important branch of the subject. The general
fault of hands is that they are too much alike; in many instances
they are the same, excepting that the minute hand is a little longer
than the hour. The dial shown on the left of Fig. 24 was designed by
me for a public clock and can be read twice as far away as the usual
dial. Just why we should make the worst dials and hands for public
clocks in the United States is more than I can find out, for there
is no possible excuse, since the "spade and pointer" hands have been
known for generations. Figure 45 is offered as a properly designed
dial for watches and domestic clocks, having flat-faced Gothic
figures of moderate height, leaving a clear center in the dial, and
the heavy "spade" hour hand reaching only to the inner edges of the
figures. For public clocks the Arabic numerals are the worst, for at
a distance they look like twelve thumb marks on the dial; while the
flat-faced Roman remain distinct as twelve clear marks.
[Illustration: Fig. 41--Musical Watch, Repeating Hours and Quarters]
Do you know that you do not read a public clock by the figures, but
by the position of the hands? This was discovered long ago. Lord
Grimthorp had one with twelve solid marks on the dial and also speaks
of one at the Athenæum Club, both before 1860. The Philadelphia City
Hall clock has dials of this kind as shown on right side of Fig. 24.
It has also good hands and can be read at a great distance. Very few
persons, even in Philadelphia, know that it has no hour numerals on
its dials. Still further, there is no clock in the tower, the great
hands being moved every minute by air pressure which is regulated by
a master clock set in a clock room down below where the walls are 10
ft. thick. Call and see this clock and you will find that the City
Hall officials sustain the good name of Philadelphia for politeness.
Generally, we give no attention to the hour numerals, even of our
watches, as the following proves. When you have taken out your watch
and looked at the time, for yourself, and put it back in your pocket,
and when a friend asks the time you take it out again to find the
time for him! Why? Because, for yourself, you did not read hours and
minutes, but only got a mental impression from the position of the
hands; so we only read hours and minutes when we are called on to
proclaim the time.
[Illustration: Fig. 42--Syrian Dial]
We must find a little space for striking clocks. The simplest is one
blow at each hour just to draw attention to the clock. Striking the
hours and also one blow at each half hour as well as the quarter
double blow, called "ting tong" quarters, are too well known to need
description. The next stage after this is "chiming quarters" with
three or more musical gongs, or bells. One of the best strikers I
have has three trains, three weights and four bells. It strikes
the hour on a large bell and two minutes after the hour it strikes
it again, so as to give you another chance to count correctly. At
the first quarter it repeats the last hour followed by a musical
chord of three bells, which we will call _one triple blow_: at the
second quarter the hour again and two triple blows and at the third
quarter, the hour again and three triple blows. Suppose a sample
hour's striking from four o'clock, this is what you hear, and there
can be no mistake. "Four" and in two minutes "four"--"four and one
quarter"--"four and two quarters"--"four and three quarters," and the
same for all other hours. This is definite, for the clock proclaims
the hour, or the hour and so much past. It can be set silent, but
that only stops it from striking automatically, and whether so set
or not, it will repeat by pulling a cord. You awake in the night
and pull the cord, and then in mellow musical tones, almost as if
the clock were speaking, you hear--"four and two quarters." This I
consider a perfect striking clock. It is a large movement of fine
workmanship and was made in the department of the Jura, France.
When a clock or watch only repeats, I consider the old "five-minute
repeater" the best. I used this method in a clock which, on pulling
the cord, strikes the hour on a large bell and if that is all it
strikes, then it is less than five minutes past. If more than five
minutes past it follows the hour by one blow on a small bell for
every five minutes. This gives the time within five minutes. It is
fully described and illustrated in "Machinery," New York, for March,
1905. Just one more. An old Dutch clock which I restored strikes the
hour on a large bell; at the first quarter it strikes one blow on a
small bell; at the half hour it strikes the last hour over again on
the small bell; at the third quarter it strikes one blow on the large
bell. But this in spite of its great ingenuity, only gives definite
information at the hour and half hour.
[Illustration: Fig. 43--Hebrew Numerals]
[Illustration: Fig. 44--24-Hour Watch]
Of curious clocks there is no end, so I shall just refer to one
invented by William Congreve, an Englishman, over one hundred years
ago, and often coming up since as something new. A plate about 8 in.
long and 4 in. wide has a long zigzag groove crosswise. This plate
is pivoted at its center so either end can be tipped up a little.
A ball smaller than a boy's marble will roll back and forth across
this plate till it reaches the lower end, at which point it strikes
a click and the mainspring of the clock tips the plate the other way
and the ball comes slowly back again till it strikes the disk at the
other end of the plate, etc. Every time the plate tips, the hands
are moved a little just like the remontoir clock already described.
Clocks of this kind are often used for deceptive purposes and those
ignorant of mechanics are deceived into the belief that they see
perpetual motion. The extent to which modern machine builders are
indebted to the inventions of the ancient clock-maker, I think, has
never been appreciated.
[Illustration: Fig. 45--Domestic Dial by James Arthur]
In its earlier stages the clock was almost the only machine
containing toothed gearing, and the "clock tooth" is still necessary
in our delicate machines. It is entirely different from our standard
gear tooth as used in heavy machines. The clock-makers led for a
long time in working steel for tools, springs and wearing surfaces.
They also made investigations in friction, bearings, oils, etc.,
etc. Any one restoring old clocks for amusement and pleasure will
be astonished at the high-class mechanics displayed in them--nearly
always by unknown inventors. Here is an example: The old clock-maker
found that when he wished to drill a hole in a piece of thick wire
so as to make a short tube of it, he could only get the hole central
and straight by rotating the piece and holding the drill stationary.
By this method the drill tends to follow the center line of
rotation; and our great guns as well as our small rifles are bored
just that way to get bores which will shoot straight. The fourth and
last chapter will deal with the astronomical motions on which our
time-keeping is founded, our present hour zones of time, and close
with suggestions for a universal time system over the whole world.