Part 6

Very often this air which is suddenly forced back by the power of the explosion is thrown against houses at a distance. These houses may be so strongly built as to be able to withstand the effect of the explosion, but still certain parts of them, such as the windows and the bricks of the chimney, may not be able to withstand this sudden pressure of air against them and they are forced in. The wind from such an explosion acts on the outside of the windows just the same as though you stood on the outside with your hands against the windows and pushed them in. Anything that is thrown against a window with more force than the window glass can resist will break the window, and even slight explosions may be so powerful as to throw the air back and away from them with such force as to break windows at a great distance--even a mile or more away.

Why Do Some Things Bend and Others Break?

When an outside force is applied to some objects, some of them will bend and others break. It is due to the fact that in some things the particles have the faculty of sticking together or hanging on to each other, and it is very difficult to break them away from each other. In such instances, as in the case of a wire, the article will bend when we apply the power to it and it will not break, because the particles which make up the wire have the faculty of hanging on to each other. A piece of glass, however, can be broken right in two by the application of no more force than was used to bend the wire, because the particles which make up the glass haven’t the faculty to hang on to each other. If you continue to bend a wire back and forth, however, at the same point, it will finally break apart, because you eventually overcome the ability of the particles in the wire to hang on to each other.

It all depends upon the hanging-on ability. Sometimes in undergoing different processes an article which will ordinarily only bend will become very brittle or breakable. A steel wire may bend but if you make a steel wire very hard it becomes brittle. On the other hand, glass is very brittle ordinarily, but if you make it very hot, you can bend it into any shape you wish, and thus the glass-worker makes different shapes to various dishes; lamp chimneys, bottles, etc., by heating glass and then bending it. When it becomes cool again, it also becomes brittle or breakable as before.

Why Does a Ball Bounce?

When you throw a ball against the floor in order to make it bounce the ball gets out of shape as soon as it comes in contact with the floor. As much of it as strikes the floor becomes perfectly flat, and because the ball has a quality known as elasticity, which means the ability to return to its proper shape, it returns to its shape immediately and in doing so forces itself back into the air and that is the bounce.

Of course, the first thing we think of when we consider something that bounces is a ball, and in most cases a rubber ball. We are more familiar with the bouncing qualities of a rubber ball. Other balls, like standard baseballs, are not so elastic as a rubber ball filled with air, but a solid-rubber ball is more elastic and some golf balls are much more elastic than a solid-rubber ball. The principle is the same, when you drive a golf ball, excepting that when you bounce a ball on the floor the floor does the flattening and when you drive a golf ball, the golf club does the flattening. A baseball flies away from the bat for the same reason. When you meet a fast-pitched ball squarely on the nose with a good swing, it goes farther and faster than when you hit a slow-pitched ball with an equal swing, because in the case of the fast-pitched ball you flatten the ball out more, and it has so much more to do to recover its proper shape that it bounces away from the bat at much greater speed and goes much further unless caught than a slow-pitched ball under the same circumstances.

What Makes a Ball Stop Bouncing?

A bouncing ball, when you first throw it against the wall bounces back at you about as fast as you throw it, but if you do not catch it on the rebound, it goes to the floor again, because the law of gravitation which is the pulling power of the earth, pulls it down again. When it strikes the floor it is again flattened to a certain extent and bounces up again, but does not come back so high. It goes on striking the floor and bouncing back into the air again each time a shorter distance, until the force of gravity has actually overcome its tendency to bounce back.

When you bounce a ball on the floor and it bounces up again, the motion of the ball through the air is affected by the friction that the contact with the air produces and this friction of the air overcomes part of the bouncing ability in the ball also.

What Makes a Cold Glass Crack if We Put Hot Water Into It?

Hot water will not always cause a cold glass to crack, but is very apt to, especially a thick glass. The very thin glasses will not crack. The test tubes used by chemists are made of very thin glass, and will not crack when hot liquids are poured into them.

When a glass cracks after you have poured a hot liquid into it, it does so because, as soon as the hot liquid is put in, the particles of glass which form the inside of the glass become heated and expand. They begin to do this before the particles which form the outside of the glass become heated, and in their efforts to expand the inside particles of glass literally break away from the particles which form the outside, causing the crack. The same thing happens if you put cold water into a hot glass, excepting in this instance the inside particles of the glass contract before the particles which form the outside of the glass have had time to become cool and do likewise.

What Causes the Gurgle When I Pour Water from a Bottle?

The air trying to get in causes the gurgle. Air has one strong characteristic which stands out above everything else. It wants to go some place else all the time. When it learns of a place where there is no air it wants to go there above all things, and goes at it with a rush.

Now, when you turn a bottle full of water upside down, the water comes out if the cork is out, of course, and as soon as the water starts out the air strives to get in, and every time you hear a gurgle you know the air is getting in. Every gurgle is a battle between the water and the air. Sometimes the air comes and pushes the water back enough to let it slide into the bottle; sometimes the water pushes the air back, and thus they fight back and forth. The water always gets out and the air always gets in. In doing so they make the gurgle.

Where Does the Part of a Stocking Go That Was Where the Hole Comes?

Perhaps this is a foolish question, but many boys and girls have been puzzled for an answer to it. When you put your stockings on they have no holes in the feet, and at night, when you take them off, there are often quite large holes in them. The answer is the same as in the case of the lead in the lead-pencil. The lead in the pencil wears away. You can see it wear away because that is what makes the marks.

When a hole is coming into your stocking, the stocking on your foot is being rubbed between your foot and something else (probably some part of your shoe) and this constant rubbing will wear through the yarns with which the stocking is knitted. Of course, the yarns in the stocking are stretched somewhat when it is on your foot and the rubbing finally cuts through the threads and releases the tension of the threads of yarn, so that not always is as much stocking lost as the size of the hole. But, if you were to look carefully at your foot and inside your shoe, when you first take the stocking off and see the hole, you would find little particles of yarn all about.

Why Do Coats Have Buttons On the Sleeves?

The practice of putting buttons on coat sleeves, which serve no useful purpose at all and do not add to the beauty of the coat, is a relic of very old days.

There was a time when people did not use handkerchiefs, and it was common practice for men to wipe their noses on their sleeves. They had coats also in those days, but they did not have buttons on the sleeves. One of the old kings finally developed the idea of dressing his soldiers in fancy uniforms and, as he sat in his palace and reviewed his troops, he noticed many of them using the sleeves of their coats as handkerchiefs. He immediately issued a decree that all sleeves should have a row of buttons sewed on them, but at a point directly opposite to where they are now on the sleeves. This was done to remind the soldiers that the sleeves of their beautiful uniforms were not to be used as handkerchiefs, and those who attempted to draw their sleeves in front of the nose were quickly reminded of the decree by the buttons which scratched them. And so the buttons really had a quite useful purpose at one time, and so also all sleeves had buttons sewed on to them at this place. Later on, however, when the unsightly practice had been cured and people had learned to use handkerchiefs, the buttons remained as a decoration, but their former purpose was lost sight of. Then some tailor or leader of fashion had the buttons set on the under side of the sleeves for a change, and it became the fashion to have them there, and the tailors have been sewing them there ever since.

Why Has a Long Coat Buttons on the Back?

The buttons on the back of a long coat, i. e., one with skirts, had a more sensible reason originally. At one time the skirts of such coats were made very long, and when the wearer moved quickly the tails of the coat flapped about the legs and interfered with progress. So an ingenious gentleman had buttons sewed on to the back and buttonholes made in the corner of his coat-tails. Then when he was in a hurry he simply buttoned up his skirts and went his way comfortably.

The Story in the Telephone

~WHAT HAPPENS WHEN WE TELEPHONE~

Mrs. Smith, at “Subscriber’s Station No. 1,” desires to telephone to Mrs. Jones at “Subscriber’s Station No. 2.” When she lifts her receiver, the movement causes a tiny white light to appear instantly on the switchboard at the Central Office. Directly beneath this light is another and larger lamp, which glows in a way to attract the operator’s attention immediately.

The operator inserts a “plug” in a little hole on the switchboard called a “jack,” directly above the tiny light which appeared when Mrs. Smith lifted the receiver. This connects her to Mrs. Smith’s line. Then she pushes a listening key on the board, connecting her telephone set to the line. “Number, please?” she calls.

Mrs. Smith gives the number; the operator repeats it to be sure there is no mistake, places another “plug” in a “jack” corresponding to the number of Mrs. Jones’ telephone and makes the connection.

Each subscriber’s telephone has a particular signal on the switchboard to which it is connected by a pair of wires. Mrs. Smith’s wires run from her instrument to the nearest “cable terminal,” a gathering point for the wires of various telephones in her neighborhood. Here they form part of a group of wires going to the Central Office. These groups, called cables, are made up of from 50 to 600 pairs of wires, according to the telephone needs of the district the “terminal” serves.

When the wires reach the Central Office they pass through the “cable vault” to the “main distributing frame,” which is the Central Office terminal of the cable.

When the wires come to this frame they are in numbered order in the cable. Subscribers living next door to Mrs. Smith may have entirely different call numbers and yet use consecutive wires. It is the task of the main frame to redistribute these wires, so that they will be arranged according to their call numbers and to make it possible to connect Mrs. Smith’s line with the line of any other subscriber with the least possible delay. This frame has two parts: the “vertical side” and the “horizontal side.” Before the wires are redistributed they are taken to pairs of springs equipped with devices for protecting the lines against outside currents.

After leaving the main frame they are taken to the “intermediate distributing frame,” the central connecting point for various branches of the lines going to the switchboard, signaling and other apparatus. From the “horizontal side” of this frame, wires go to the switchboard, where they terminate in little holes known as “multiple jacks.” They also connect with the line and position message registers, where the calls from each Line and the calls handled at each operator’s position at the switchboard are recorded. The “multiple jacks” are additional terminals placed at necessary intervals throughout the switchboard, where they can be used by operators to make connections with any other line on the board.

From the “vertical side” of the intermediate frame Mrs. Smith’s wires reach the “line and cut-off relay,” an electrically controlled switch which turns on the light signal that appears on the switchboard when she lifts the receiver from the hook. This “line relay” also extinguishes the light when the operator makes the connection, or when Mrs. Smith returns the receiver to the hook.

The swift moving electric current that was set in motion when Mrs. Smith began the call, instantaneously passes through all these devices for safeguarding and protecting the subscriber’s telephone service. The light announcing Mrs. Smith’s desire to make a call is called the “line lamp,” and is flashing on the switchboard. Directly beneath it is the “pilot lamp,” which glows whenever any “line lamp” lights. With the “line lamp” is a “jack” or terminal, where connection can be made with Mrs. Smith’s line. This is the “answering jack.”

When the operator sees the flashing signal of Mrs. Smith’s “line lamp,” she inserts one end of a pair of “connecting cords,” which are on the board before her, in the “answering jack” for Mrs. Smith’s line. These “connecting cords” are flexible conductors that put the wires of subscribers in electrical connection. Then she pushes forward the “operator’s key” directly in front of her and is connected with Mrs. Smith’s line.

The operator ascertains the number wanted and places the other “connecting cord” in the “jack” corresponding to Mrs. Jones’ line. If she finds she cannot herself connect with Mrs. Jones’ “jack,” because it is on another part of the board out of her reach, she makes a connection with another operator who can reach Mrs. Jones’ line. The second operator then makes the connection with Mrs. Jones’ “multiple jack” and places her line in connection with Mrs. Smith’s line at the first operator’s position. At the same time the first operator pushes the operator’s key back, thus ringing Mrs. Jones’ bell.

“Supervisory lamps” on the board before her, connected with the “connecting cords,” tell the operator when Mrs. Jones answers the summons. They flash when the connection is made and one goes out just as soon as Mrs. Jones takes the receiver from the hook to answer. If one of these lamps flashes and dies out alternately it tells the operator that either Mrs. Smith or Mrs. Jones is trying to attract her attention and she connects herself and ascertains the party’s wishes. When both subscribers “hang up,” both lights flash to indicate the end of the conversation. The operator then disconnects the cords from the subscribers’ “jacks” and presses the “message register” button recording the call against Mrs. Smith.

How the Telephone Came to Be.

It is hard to realize that there was once a time, not so very many years ago, when the telephone was regarded as a scientific toy and hardly anyone could be found willing to invest any money in the development of the telephone business.

The story of Professor Alexander Graham Bell’s wonderful invention is full of romantic interest and the early days of its exploitation were replete with dramatic incidents.

~THE MEN WHO MADE THE TELEPHONE~

Young Bell had come to America in 1870 in search of health, the family settling at Brantford, Canada. He numbered among his forebears many distinguished professional men. For three generations the Bells had taught the laws of speech in the universities of Edinburgh, Dublin and London. He himself was an accomplished elocutionist and an expert in vocal physiology.

During the year spent in Canada in regaining his health, Bell taught his father’s method of visible speech to a tribe of Mohawk Indians and began to think about the “harmonic telegraph.”

In 1871 young Alexander Bell accepted an offer from the Boston Board of Education to teach the “visible speech” method in a school for deaf mutes in that city.

For two years he devoted himself to the work with great success. He was appointed a professor in the Boston University and opened a school of “Vocal Physiology” which was at once successful.

He might have continued his career as a teacher had it not been that his active brain still clung to the “harmonic telegraph” idea and his inventive genius demanded an outlet.

So we find him in 1874 working out his idea of the “harmonic telegraph,” the perfection of which meant a fortune to the young inventor. That he never realized his goal was due to the fact that while experimenting, he made a discovery which led to a far greater invention and one that was fraught with more benefit to mankind than the “harmonic telegraph” could ever have been.

It was while working with his faithful man Friday, Thomas A. Watson, in the dingy little workrooms on Court Street, Boston, that Bell got the inspiration which made him turn from the “harmonic telegraph” to devote himself to the invention which was destined to make his name famous--the speaking telephone.

~THE FIRST SOUND OVER A WIRE~

Mr. Watson has dramatically described the incident as follows: