Part 44

On this page we see some of the first telegraph instruments, in fact, the very instruments which Professor Morse used in the early demonstrations of his invention. These instruments may be seen in the Smithsonian Institution at Washington, D. C. The key is known as the Vail key, because it is supposed to have been constructed by Alfred Vail, who worked with Morse in his experiments with the telegraph. As can be seen it is very simple. One wire was connected to the spring piece and the other to the post beneath it. When the key was pressed down, the contact was made and an impulse sent over the wire, either a dot, if the key was pressed down and immediately released, or a dash if it were held down for just the fraction of a second before releasing.

From the very first it was found that relays were necessary, because the current after coming a long way over the wire often was not strong enough to operate the recording instrument. Therefore, this weak current was made to go though the electro-magnets of the relay, magnetizing these and pulling to the left the upright arm which can be seen in the photograph with a little block of iron attached to it. This arm, when pulled by the magnets, made a contact at the top and allowed a strong current from a battery to flow through the magnets of the recording instrument.

The first practical recording telegraph instrument devised by Morse is shown. It looks like a clumsy affair compared to the instruments of to-day, but it worked so effectively as to convince people of the possibilities of the great invention. In the wooden box, attached to the frame at the right, is clockwork which pulled a paper tape at an even rate of speed over a pulley just beneath a needle point. This needle point is attached to a light framework having a piece of iron fastened in it. Below this iron are the electro-magnets, and when they received an impulse of current from the battery, through the relay, they pulled down the frame so that the point made a mark upon the paper tape which moved under it. Thus in the tape appeared a series of dots and dashes, which the operator, knowing the Morse Code, could easily translate into English.

The Story in an Ocean Cable

What is a Cable Made of?

A submarine telegraph cable as usually made consists of a core in the center of which is a strand of copper wire which varies in weight from seventy to four hundred pounds to the mile. Strands of copper wire instead of one thick wire of copper are used, because the former is more flexible. The copper conductor is covered with several coatings of rubber of equal weight to the copper wires. After this comes a coating of jute serving, then a layer of galvanized iron wires and finally a layer of yarn and compound which forms the outer covering of the cable. In addition to this where the cable lays among rocks that might injure it, chains are securely wrapped around it, so as to prevent wear and tear as much as possible.

You may not have known it, but the cable which lies on the bottom where the water is deepest is never so large as nearer the shore or in shallow water. Little by little the men who lay and look after cables have found that it is best to have a specially constructed outer covering for different depths and character of bottoms so as to provide the least possible danger of damage through the action of the water on the bottom.

How is a Cable Laid?

When the cable of sufficient length is completed, it is carried to a specially equipped vessel which has a great tank for holding the cable and the necessary machinery for lowering it over the end of the ship into the water. The cable is carefully coiled in the tank, the different coils being prevented from adhering by a coat of whitewash. First then, a sufficient length of cable is paid out to reach the cable house or shore. Here it is finally tested to see that the entire length of cable is in working order. If satisfactorily tested, the vessel steams slowly away on the course outlined, paying out the cable as she goes.

The vessel must pay out more than a mile of cable for every mile she travels because there must be enough slack allowed at the same time to provide for the unevenness of the bottom of the sea. For this purpose the amount of cable paid out must be measured. This is done by the paying-out machine, which is shown in one of the pictures. The difference between the speed of the ship and the amount of cable paid out gives the amount of slack. Too much slack would also be bad, so that it is a very pretty problem to pay out just enough and both the speed of the vessel and the rate of paying out the cable must be watched carefully.

One of the greatest wonders accomplished by the ingenuity of man is the ocean telegraph, by which we flash messages back and forth under the sea between the continents and completely around the world.

Hardly had the telegraph become an established fact, before Professor Morse, who made the telegraph practical, expressed the belief that a telegraph line to Europe by means of a wire laid on the bottom of the ocean was easily possible at some future time. Mr. Cyrus W. Field, the first to lay an ocean cable successfully, heard him and in his own mind said “Why not now?” The idea fixed itself so thoroughly in his resolute mind that he soon said to himself “It shall be done,” and went to work, and labored incessantly through twelve years of failure and discouragement before he accomplished his task, which was a great compliment to this giant of American stick-to-it-iveness.

While many doubted the feasibility of the project and others thought it the dream of a disordered brain, Mr. Field found many who believed in him and his idea and who loaned him their financial support for the undertaking.

American genius had not at that time asserted its supremacy in mechanics and so the first cable had to be made in England; so Mr. Field ordered one long enough to stretch from the west coast of Ireland to the eastern point of Newfoundland. English capitalists subscribed the money and the United States provided the vessel in which to store and from which to drop the cable into the ocean.

Upon the first attempt to lay the cable, every thing went along nicely for six days, and then suddenly the cable broke when three hundred and thirty-five miles had been laid, and many said it could not be done. Mr. Field, however, full of American pluck and determination, said “We will try again.” A second attempt was made with two ships, the U. S. S. “Niagara” and H. M. S. S. “Agamemnon.” Each ship carried half the cable and they traveled in company to the middle of the ocean. There the two pieces of the cable were spliced together and the ships started for the shores in opposite directions. Again, however, when only a little of the cable had been paid out--a little more than one hundred miles in fact--the cable broke and both ships were forced to return to England.

In his third attempt the cable was finally laid clear across the ocean and fastened at both ends. When tried it was found to work successfully and Queen Victoria and President Buchanan were able to exchange greetings upon the achievement of a wonderful work. The people celebrated the event on both sides of the ocean, but in the midst of the festivities, while a message was being flashed, something happened to the cable--what, we have never been able to learn--and the cable was silent, forever.

Nothing daunted, however, Mr. Field by his great courage induced his backers to buy him another cable and the “Great Eastern” sailed upon what was to be a most successful mission. Starting from the American side with the greatest steamship then known in charge of the previous cable, the other end was successfully landed at Hearts Content, Ireland, on July 27, 1866, in perfect working order, and the question of the ocean telegraph was solved.

Making repairs to a cable where it comes out of the sea on to a bold rocky shore. Note how the cable is wound with chain to protect it from the rocks.

THE STORY IN A RAILWAY LOCOMOTIVE

The Story in the Wireless

What is the Principle of the Wireless Telegraphy?

Drop a stone in a pool of water. Circular waves or ripples will travel outward in all directions. That is the principle of wireless telegraph.