Clocks and watches are often called “timekeepers,” but they do not keep
time. Nothing can keep it. It is constantly flying along, and carrying
us with it, and we cannot stop it. What we call “time keepers” are
really time measures, and are made to tell us how rapidly time moves, so
that we may regulate our movements and occupations to conform to its
flight.
Of course, you understand that measurement of anything is the comparing
of it with some established standard. So that if you want to measure the
length of anything you use a rule or a yard stick, or some other scale
which is graduated into fractions of the whole standard measure. Do you
know that the United States government has in a secure, fireproof vault,
in one of the government buildings in Washington, a metal bar which is
the authorized standard “yard” of this nation? It is a very carefully
made copy of the standard yard of Great Britain. I believe that each one
of the United States has also a standard which must agree in length with
the government, or national standard. The same thing is true concerning
standards of capacity, and standards of weight. But no vault can contain
the authorized standard of time. Yet there is such a standard. And it is
as accessible to one country as to another, and it is a standard which
does not change. But, because all other time measures are more or less
imperfect, our government tries to compare its standard clock with the
ultimate standard every day.
The first mention of time which we have is found in the Book of Genesis,
where it is written “and the evening and the morning were the first
day.” That statement gives a “measure” which was sufficient for the
purpose intended, but there is nothing very accurate in it. If it had
said “the darkness and the light” were the first day, it would have been
just as accurate. The people who lived in those far-off days had no
special occasion to know or to care what time it was. We may suppose
that they were hungry when they waked at sunrise, and if they had no
food “left over” from the previous day’s supply they would have to
hustle and find some, and if possible secure a little surplus beyond
that day’s needs, and so they would work, or hunt, until the “evening”
came and the sun disappeared. When a man was tired, and the sun was hot,
he sat down under a tree for shelter and rest. As he sat under the tree
and looked about him he could not fail to notice that upon the ground
was a shadow of the tree under which he sat. And as he was tired and
warm he lay down and fell asleep, and when he woke, he again saw the
shadow, but in another place. He noticed that the same thing occurred
every day. He saw also that in the morning the shadow was stretched out
in one direction, and that in the evening it lay in exactly the opposite
direction, and that every day it moved very nearly the same, so he put a
mark on the ground about where the shadow first appeared, and another
mark at the place where it disappeared. Then one day he stuck his staff
in the ground about half-way between the places of the morning and the
evening shadows, which served as a noon mark. As the staff cast a shadow
as readily as did the tree, the man found that it was really a better
index of time than was the tree shadow, for it was much smaller and more
clearly defined, and so he put up a straight stick in the ground near
the hut in which he lived, and as the ground was level and smooth he
drove a lot of little stakes along the daily path of the shadow, and in
that way divided the day into a number of small parts. That was a crude
“sun dial.” (The Bible tells of the sun dial in the thirty-eighth
chapter of Isaiah.) But there was nothing very accurate in the sun dial.
Several hundred years later the days were divided into sections which
were called “hours,” such as the “sixth hour” (noon), the “ninth hour”
(three o’clock), the “eleventh hour” (five o’clock), etc. There was,
however, nothing very accurate in those expressions, which simply
indicate that there were recognized divisions of time, but with no
suggestions as to the means used to determine their limits or
boundaries. It is recorded of Alfred the Great, who lived in the ninth
century, A. D., that he was very methodical in his employment of time,
and in order to insure a careful attention to his religious duties as
well as his kingly duties, he divided the day into three parts, giving
one part to religious duties, one to the affairs of his kingdom, and the
remainder to bodily rest. To secure an equal division of the day he
procured a definite quantity of wax which he had made into six candles,
of twelve inches in length, and all of uniform weight, for he found that
each inch in length of candle would burn for twenty minutes--one candle
for each four hours. This was an approach toward accuracy and it was
effective for night use as well as for the daytime.
[Illustration: ASSEMBLING DEPARTMENT IN A FAMOUS AMERICAN WATCH
FACTORY]
Perhaps the earliest mechanical time measure was the clepsydra, or water
clock. It is quite probable that, in its earliest form it consisted of a
vessel containing water, which was allowed to escape through a small
orifice. Suitable marks, or graduations, on the sides of the vessel
served to indicate the lapse of time as the water gradually receded.
This device was constructed in a variety of forms, some of which
employed some simple mechanism also; but from their nature they could
not give very accurate indications concerning the passage of time. The
“hour glass” was another form of time indicator, which was capable of
uniform, though extremely limited, action. It is said that its original
use was to limit the length of sermons.
It is interesting to note that discoveries and inventions, which may
seem slight in themselves, sometimes form the basis of, or contribute
to, other important inventions. In the year 1584 a bright young Italian
was sitting in the gallery of the cathedral, in the City of Pisa, and as
the lofty doors of the building opened to admit the incoming worshipers,
a strong draft of air caused the heavy chandelier, which was suspended
from the lofty ceiling, to swing quite a distance from its position of
rest. This unusual movement attracted the attention of the young man,
and as he continued to watch its deliberate movements, he did more than
watch. He thought--for he noticed that the time occupied by the movement
of the chandelier from one extreme position to the opposite point,
seemed to be exactly uniform. He wondered why. It is the careful
observation of things, and the trying to learn why they are as they are,
and why they act as they do, that enables studious people to discover
the laws which govern their actions. This young man, Galileo, was a
thinker, and while some of his conclusions and theories have since been
found erroneous, his thinking has formed the basis of much of the
scientific thought and theory of later years. Galileo’s swinging
chandelier was really a sort of a pendulum, and we have made mention of
it because it has been found that no mechanical means for obtaining and
maintaining a constant and accurate movement will equal the free
movement of a vibrating pendulum. This fact has led to its adoption as a
means of regulating the mechanism of clocks. For, when operated under
the most favorable conditions, such a clock constitutes the most
accurate “time measure” yet made.
[Illustration: VIEW OF ESCAPEMENT MAKING DEPARTMENT]
Watches are made to measure time. If anything is to be measured there
must be some standard with which to compare it, for we have seen that
measuring is a process of comparing a thing with an appropriate or
acknowledged and fixed standard. The only known standard for the
measurement of time is the movement of the earth in relation to the
stars. It has taken thousands of years for mankind to learn what is now
known concerning time. It has also taken hundreds of years to secure the
wonderful accuracy in the measuring of time which has now been attained.
We have said that nothing has been devised which will equal the accuracy
of a “pendulum clock.” A story was told of a professor of a theological
seminary who was one day on his way to a jeweler’s store, carrying in
his arms the family clock, which was in need of repairs. He was accosted
by one of his students with the question, “Look here, Professor, don’t
you think it would be much more convenient to carry a watch?” A pendulum
clock must of necessity be stationary, but it is now needful that people
should be able to have a timepiece whenever and wherever wanted. This
need is supplied by the pocket watch.
[Illustration: TIME TRAIN OF A WATCH]
If Galileo watched the swinging of the big chandelier long enough he
found that the distance through which it swung was gradually
diminishing, till, at last, it ceased to move; what stopped it? It was
one of the great forces of nature, which we call gravitation, and the
force which kept it in motion we call momentum. But gravitation overcame
momentum.
In order to maintain the constant vibration of a pendulum it is needful
to impart to it a slight force, in a manner similar to that given by a
boy who gives another boy a slight “push,” to maintain his movement in a
swing. A suspended pendulum being impossible of application to a pocket
watch, a splendid substitute has been devised--in the form of the
balance wheel of the watch, commonly called the “balance.” The balance
is, in its action and adaption, the equivalent of the vibrating, or
oscillating, pendulum; and the balance spring (commonly called the
hairspring), which accompanies it, is in its action equivalent to the
force of gravity in its effect upon a pendulum. For the tendency and (if
not neutralized by some other force) the effects of the hairspring upon
the watch balance, and of gravitation on the pendulum, are to hold each
at a position of rest, and consequent inaction.
[Illustration]
[Illustration]
But we have in a pocket watch a “mainspring” to actuate the train of
gear wheels which by their ultimate action give the delicate “push” to
the balance wheel at distinct intervals, and so keep the balance in
continued motion. In the same manner, the “weight” of a clock, acting
through the force of gravity, carries the various wheels of the clock
train, and gives the slight impulse to the swinging clock pendulum.
Both clocks and watches are “machines” for the measurement of time, and,
therefore, it is absolutely imperative that their action must be
constant, and, if accurate time is to be indicated, the action must be
uniform.
[Illustration: INTERIOR OF ASTRONOMICAL OBSERVATORY, SHOWING TRANSIT
INSTRUMENT. USED TO OBTAIN CORRECT LOCAL TIME, BY OBSERVING THE PASSAGE
OF STARS ACROSS THE MERIDIAN]
[Illustration: BALANCE COCK AND PATENT MICROMETRIC REGULATOR; ALSO
BALANCE WHEEL AND HAIR SPRING, SHOWING PATENT HAIR SPRING STUD]
The illustration shows the “time train” of an ordinary pocket watch. The
various wheels are here shown in a straight line, so that their
successive order may be seen, but for economy and convenience they are
arranged in such way as is most convenient when constructing a pocket
watch. The large wheel at the left is the “main wheel,” called by
watchmakers the “barrel.” In it is coiled the mainspring--a strip of
steel about twenty-three inches long, which is carefully tempered to
insure elasticity and “pull.” The outer end of the mainspring is
attached to the rim of the barrel, and the inner end to the barrel
arbor. Bear in mind the fact that the power which is sufficient to run
the watch for thirty-six hours or more, is not in the watch itself. It
is in yourself, and by the exertion of your thumb and finger, in the act
of winding, you transfer that power to the spring, and thereby store the
power in the barrel, to be given out at the rate which the governing
mechanism of the watch will permit. The group of wheels here shown are
known as the “time train,” and the second wheel is called the “center,”
because that, in ordinarily constructed watches, is located in the
center of the group, and upon its axis are put the “hour hand” and the
“minute hand.” On the circumference of the barrel are gear teeth, and
those teeth engage corresponding teeth on the arbor of the center. These
arbor teeth are in all cases called, not “wheels” but “pinions,” and in
watch trains the wheels always drive the pinions. Next to the center
comes the third pinion and wheel, and then the fourth, which is the last
wheel in the train which has regular gear teeth. Now let us look back a
little and see that the wheel teeth of the barrel drive the center
pinion, and the center wheel drives the third pinion and the third wheel
drives the fourth pinion, etc. The speed of revolution of the successive
wheels increases rapidly. The center wheel must revolve once in each
hour, which is 6-1/2 times faster than the barrel. The third wheel turns
eight times faster than the center, and the fourth wheel turns 7-1/2
times faster than the third, or 60 times faster than the center, so that
the fourth pinion, which carries the “second hand,” will revolve 60
times while the “center,” which carries the minute hand, revolves once.
If we should put all the wheels and pinions in place, and wind up the
main spring, the wheels would begin to turn, each at its relative rate
of speed, and we should find that, instead of running thirty-six hours,
it would have run less than two minutes. What was needed was some device
to serve as an accurate speed governor--and the attainment of this
essential device is the one thing on which accurate time measuring
depends. Without any mention of the various attempts to produce such a
device, let us, as briefly as possible, describe the means used in most
watches of American manufacture. While there are several distinct parts
of this device, each having its individual function, they may be
considered as a whole under the general term of “the escapement.”
Returning now to the fourth pinion, we see that it also carries a wheel,
which engages another little pinion, called the escape pinion. This
escape pinion also carries a wheel, but it is radically different in
appearance, as well as in action, from any of the previously mentioned
wheels. An examination of the “escape wheel” would show that it has a
peculiarly shaped piece, which is called the “pallet,” the extended arm
of which is called the “fork.” The fork encloses a sort of half-round
stud or pin. This stud projects from the fact and near the edge of a
small steel disc. The stud is formed from some hard precious stone and
is called the “jewel pin,” or “roller pin,” and the little steel disc
which carries it is called the “roller.” In the center or axial hole of
the roller fits the “balance staff,” which staff also carries the
“balance wheel,” and the balance spring, commonly called the “hair
spring.” The ends of the balance staff are made very small so as to form
very delicate pivots which turn in jewel bearings. The balance wheel
moves very rapidly, and, therefore, its movement must be as free as
possible from retarding friction, so its bearing pivots are made very
small.
[Illustration: A DEVICE FOR THE GOVERNING OF SPEED IS THE ONE THING ON
WHICH ACCURATE TIME MEASURING DEPENDS]
[Illustration: _WALTHAM TAPER SHOULDER DETACHABLE BALANCE STAFF._]
Now that we have given the names of each of the different parts which
compose the escapement, let us see how they perform their important work
of governing the speed of the little machine for measuring time. In the
escape wheel, the left arm of the pallet rests on the inclined top of
one of the wheel teeth. This is the position of rest. If we wind up the
mainspring of the watch it will immediately cause the main wheel to
turn, and, of course, that will turn the next wheel, and so on to the
escape wheel. When that wheel turns to the right, as it must, it will
force back the arm of the pallet which swings on its arbor. In swinging
out in this way it must also swing in the other pallet arm, and that
movement will bring it directly in front of another wheel tooth, so that
the wheel can turn no further. It is locked and will remain so until
something withdraws it. When the pallet was swung so as to cause this
locking, the fork was also moved, and as it enclosed the roller pin,
that too was moved and carried with it the roller and the balance wheel,
and in so doing it deflected the hair spring from its condition of rest.
And as the spring tried to get back to its place of rest it carried back
the balance also. In going back, the balance acquired a little momentum,
and so could not stop when it reached its former position, but went a
little further, and, of course, the roller and its pin also went along
in company, the pin carrying the fork and the pallet swinging in the
other direction, which unlocked the escape wheel tooth. Its inclined
top gave the pallet a little “push” so that the first pallet was locked,
forcing the fork and roller, and the balance and hair spring, to move in
the opposite direction. And so the alternate actions proceed, and the
balance wheel travels further each time, until it reaches the greatest
amount which the force of the mainspring can give. But before this
extreme is reached, the momentum of the revolving balance carries the
roller pin entirely out of the fork. As the fork is allowed to move only
just far enough to allow the pin to pass out, it simply waits until the
fork returns and enters its place, only to escape again on the other
side. And so the motions continue to the number of 18,000 times per
hour. If that number can be exactly maintained, the watch will measure
time perfectly. But if it should fall short of that exact number only
once each hour, it would result in a loss of 4.8 seconds each day, or
2.4 minutes in one month. A watch as bad as that would not be allowed on
a railroad.
[Illustration: ACCURATE MEASUREMENTS ARE ESSENTIAL TO CORRECT TIME
KEEPING]
Isn’t it wonderful that such a delicate piece of mechanism can be made
to run so accurately? And the wonder is increased by the fact that the
little machine is, to a great extent, continually moved about, and
liable to extreme changes in position and in temperature. Watches of the
highest grades are adjusted to five positions as well as to temperature.
Some are adjusted to temperature and three positions, and still others
to temperature only. The way in which a watch is made to automatically
compensate for temperature changes is interesting. Varying degrees of
heat and cold always affect a watch. It is a law of nature that all
simple metals expand under the influence of heat and therefore contract
when affected by cold. Alloys, or mixtures of different metals, act in a
similar manner, but in varying degrees. Some combinations of metals
possess the quality of relatively great expansibility. Another natural
law is that the force required to move a body depends upon its size and
weight. So it follows that with only a certain amount of available force
a large body cannot be moved as rapidly as a small one. The force of 200
pounds of steam in a locomotive boiler might be sufficient to haul a
train of six cars at a speed of thirty miles per hour, but if more cars
be added it will result in a slower speed. The same principle applies to
a watch as to a railway train. Therefore if the balance wheel becomes
larger as it grows warmer, and the force which turns the wheel is not
changed, the speed of movement must be reduced. One other natural law
which affects the running of watches is this: Variations in temperature
affect the elasticity of metals. Now the balance spring of a watch is
made from steel, and is carefully tempered in order to obtain its
highest elasticity. Increase in temperature therefore introduces three
elements of disturbance, all of which act in the same direction of
reducing the speed. First, it enlarges the balance wheel; second, it
increases the length of the spring; third, it reduces the elasticity of
the spring. To overcome these three disturbing factors a very ingenious
form of balance has been devised.
[Illustration: 170 PARTS COMPOSE A 16 SIZE WATCH MOVEMENT. (A LITTLE
MORE THAN 1/2 ACTUAL SIZE)]
A watch balance is made with a rim of brass encircling and firmly united
to the rim of steel. In order to permit heat to have the desired effect
upon this balance, the rim is completely severed at points near each of
the arms of the wheel. If we apply heat to this balance the greater
expansion of the brass portion of its rim would cause the free ends to
curl inward.
In order to obtain exactly 18,000 vibrations of the balance in an hour,
it will be seen that the weight of the wheel and the strength of the
hair spring must be perfectly adapted each to the other. The shorter the
spring is made the more rigid it becomes, and so the regulator is made a
part of the watch, but its action must be very limited or its effect on
the spring will introduce other serious disturbances. The practical
method of securing the proper and ready adaptation of balances to
springs is to place in the rims of the balance a number of small screws
having relatively heavy heads. Suppose now that we have a balance fitted
with screws of the number and weight to exactly adapt it to a spring, so
that at a normal temperature of, say, 70 degrees, it would vibrate
exactly 18,000 times per hour. When we place the watch in an oven the
heat of which is 95 degrees, we might find that it had lost seven
seconds. That would show that the wheel was too large when at 95
degrees, although just right at 70 degrees. Really, that is a very
serious matter--it would lose at the rate of 2-4/5 minutes in a day. But
after all it need not be so very serious, because if we change the
location of one screw on each half of the balance so as to place it
nearer the free end of the rim when the heat curls the rim inward, it
will carry a larger proportion of the weight than if the screws had not
been moved. It may require repeated trials to determine the required
position of the rim screws, and both skill and good judgment are
essential. It will be readily understood that numerous manipulations of
this kind constitute no small items in the cost of producing high-grade
watches.
Large quantities of the cheaper class of watches are now made by
machinery in the United States, Switzerland, France, Germany and
England. They are generally produced on the interchangeable system, that
is, if any part of a watch has become unfit for service, it can be
cheaply replaced by an exact duplicate, the labor of the watch repairer
thus becoming easy and expeditious.
* * * * *
How does a Monorail Gyroscope Railway Operate?
The last decade has brought a railway with a single line of rails, on
which the car is kept erect by the steadying power of a pair of heavy
gyroscopes, or flywheels, rotating in opposite directions at very high
velocity. There are two recent inventions of this kind, an English and a
German, practically the same in character.
The English, the invention of an Australian named Brennan, had its first
form in a model, a small car on which the gyroscopes rotated at the
enormous speed of seventy-five hundred revolutions per minute. They were
hung in special bearings and rotated in a partial vacuum, the friction
being so slight that the wheels would continue to revolve and give
stability to the car for a considerable time after the power was shut
off. Also, in such a case, supports at the side kept the car from
overturning. This model showed itself capable of traveling at high speed
on a single rail, rounding sharp curves and even traversing with ease a
wire cable hung in the air.
In 1909 a car was tried fourteen feet long and ten feet wide, capable of
carrying forty passengers. The gyroscopes in this, moved by a gasoline
engine, revolved in a vacuum at a speed of three thousand rotations a
minute. They were three and a half feet in diameter and weighed together
one and a half tons. With a full load of passengers, this car sped
easily around a circular rail two hundred and twenty yards long and
proved that it could not be upset, since when all the passengers crowded
to one side the car remained firmly erect, the gyroscopes lifting it on
the weighted sides. It is claimed that in the monorail system so
equipped with the gyroscope, a speed of more than a hundred miles an
hour is possible with perfect safety.
[Illustration: A MONORAIL GYROSCOPE CAR]
The German invention, displayed by Herr Schorl, a capitalist of Berlin,
is in many respects like the English one. The experimental car was
eighteen feet long and four feet wide, the gyroscopic flywheels being
very light, weighing but a hundred and twenty-five pounds each, while
their speed of rotation was eight thousand per minute. The same success
was attained as in the English experiments, and there seems to be a
successful future before this very interesting vehicle of travel. There
is also another type of monorail of overhead construction, the wheels
running on the rail from which the car hangs.
The fundamental principle of the gyroscope lies in the resistance which
a flywheel in rapid motion presents to any change of direction in the
axis of rotation.
The gyroscope has been utilized to give steadiness to vessels in rough
seas, and Sperry has made considerable progress in this country in
applying it to give stability to an aeroplane. One of the most
successful of the recent applications of the gyroscope is in its
connection with the marine compass. All battleships in the United States
Navy are now fitted with the gyroscopic compass. As a gyro compass is
independent of the magnetism of the earth and of the ship, and, when
running properly, always points to the North Pole, its great convenience
in vessels carrying heavy guns and armor, the attraction of which would
materially interfere with the operation of the ordinary type of compass,
is at once apparent. Another important use of the gyroscope is found in
its relation to the vertical and horizontal steering gear of the naval
torpedo, especially the Whitehead pattern. Its first application to this
purpose was made by an officer in the Austrian navy in 1895, and this
device, or an improved modification of it, such as the Angle Gyroscope,
invented by Lieut. W. I. Chambers of the United States Navy, is in use
on all torpedoes.
Why are Finger-prints Used for Identification?
The plan of identifying people by their finger-prints, although at first
used only on criminals, is now put to many other uses. It was introduced
originally in India, where it was of very great assistance to the
British authorities in impressing the natives with the fact that at last
no evasion of positive identification of culprits was possible. It was
later taken up by the Scotland Yard authorities in England, and its use
has since spread to practically every country in the civilized world.
It has been proven, to the entire satisfaction of everyone who has ever
made a careful study of the subject, that every human being has a
marking on his or her fingers which is different from that of any other
person on earth. Not only is it sure that no one else has a thumb or
finger marked like yours, but it has also been established beyond
dispute that every little detail will continue peculiar to your fingers
as long as you have them.
There are many ways in which this knowledge is used to advantage; two
methods now employed are particularly valuable. It is seldom that an
unpremeditated crime is committed without its author leaving
finger-marks on some object which is unconsciously touched, such as
silver plate, cash boxes or safes, glassware or windows, polished
wood-work, etc., and very often the professional criminal also neglects
to take precautions against leaving his signature behind him. It is then
a simple matter for the police to collect such marks for comparison with
the finger-prints of anyone to whom suspicion may be directed.
The plan has also been utilized a great deal in recent years for the
identification of enlisted men in the army and navy. Finger-prints are
made, immediately upon enlistment, of each separate finger and thumb of
both hands. Group impressions are also taken with the four fingers of
each hand pressed down simultaneously. When needed for any particular
purpose, such finger-prints are usually enlarged by means of a special
camera, to five times their natural size.