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Great Inventors and Their Inventions by  Frank P. Bachman


 

 

GUGLIELMO MARCONI

ON January 23, 1909, the world suddenly discovered that a wonderful, new, and practical invention had come into use. At daybreak of that day the passenger steamer Republic  collided with the Florida, off the coast of Nantucket Island. The Republic sent out this message: "We were struck by an unknown boat; engine room filled; [262] passengers all safe; can stay afloat." Instantly the message was caught by the Baltic, the Lorraine, and by two United States revenue cutters, and all sent their promise to help. The Baltic  arrived beside the Republic  first, and saved the lives of sixteen hundred passengers.

But how could a vessel far out in the ocean send a message? By wireless telegraphy, perfected by Guglielmo Marconi. Only eight years before this collision between the Republic  and the Florida, Marconi and an assistant sat at a table in a bare room in the Old Barracks at Signal Hill, Newfoundland. By the side of Marconi hung a telephone receiver connected with a wire which ran out of the window to a kite, floating four hundred feet over-head. Two thousand miles away, on the coast of Cornwall, England, there sat another man at the foot of a mast two hundred and ten feet high, with a wire hanging down from it connected with an electric battery and a telegraph key.

Marconi cabled to Cornwall that all was ready, then he listened, with the telephone receiver to his ear, for more than a half hour before he heard the first click. There were three of these, meaning "S," the signal he had agreed upon with the man at Cornwall. More signals came, and he listened again and again to make sure. This was the first wireless message over the ocean, and Marconi knew that his invention, upon which he had worked for years, could be made a success.

Marconi is an Italian. He received a splendid scientific training in the schools of Florence and Bologna, and showed an interest in electricity from the time he was twelve years old. One day, when he was about twenty- [263] one, while sending electric waves through the air and getting signals a mile away, he accidentally noticed that an instrument on the opposite side of a hill from the sending instrument was affected. The only way this instrument could be affected was by the electric waves passing through the hill. "If electric waves will pass through a hill, they can be made," he said to himself, "to pass long distances over the land and even over the ocean, and it will be possible to telegraph without wires." Thus was born the idea of the wireless telegraph.


[Illustration]

A WIRELESS OPERATOR.

Every boy knows that a stone dropped into a pond starts waves in all directions, and although the water only moves up and down, the waves go on and on, until they reach the shore of the pond or have spent their force. In like manner, when a current of electricity is discharged into the air, electric waves go out in all directions and keep on going until their force is spent.

In addition to a code—and the regular telegraph code is used—there is only needed, then, to send a wireless [264] message, an instrument to produce the electric waves, or a transmitter; and an instrument to collect these waves, or a receiver. The cr-a-ck, cr-a-ck of the sparks when the electric currents leap between the knobs of the transmitter is a familiar sound. The crack of these sparks at long distance stations is like thunder, and the flame is as large around as a man's wrist.


[Illustration]

WIRELESS STATION AT WELLFLEET, MASSACHUSETTS.

In the construction of instruments for a wireless telegraph station, the receiver is much harder to make than the transmitter. The most important parts are the coherer, which catches the electric waves, and the decoherer, which makes and breaks the current, producing sounds corresponding to the dots and dashes of the Morse key. Receivers are now so tuned or harmonized that they will receive electric waves only from a particular [265] transmitter. In this way, messages can be sent as secretly by wireless as by the ordinary telegraph. There are, however, signals which all receivers will catch, like the S.O.S., used by the wireless to call for help.

Even before the sinking of the Titanic, most ships were provided with wireless. Since then, all vessels sailing from American ports, and carrying fifty passengers or more, are required by law to be provided with a wireless outfit. The wireless has added greatly to the safety of the ocean; and it is extensively employed in war. At no distant date, messages will doubtless be sent without relay around the world, and it is not impossible that we may live to see the wireless of Marconi displace the older telegraph of Morse.


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