Part 6
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.
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.
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.
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.
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.
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.
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.
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.
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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.
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.
The Story in a Rifle[6]
How It Began.
A naked savage found himself in the greatest danger. A wild beast, hungry and fierce, was about to attack him. Escape was impossible. Retreat was cut off. He must fight for his life--but how?
Should he bite, scratch or kick? Should he strike with his fist? These were the natural defenses of his body, but what were they against the teeth, the claws and the tremendous muscles of his enemy? Should he wrench a dead branch from a tree and use it for a club? That would bring him within striking distance to be torn to pieces before he could deal a second blow.
There was but a moment in which to act. Swiftly he seized a jagged fragment of rock from the ground and hurled it with all his force at the blazing eyes before him; then another, and another, until the beast, dazed and bleeding from the unexpected blows, fell back and gave him a chance to escape. He knew that he had saved his life, but there was something else which his dull brain failed to realize.
_He had invented arms and ammunition!_