Credit for the first suggestion of an electric telegraph must be given to an unknown writer of the middle eighteenth century. In the Scots Magazine for February 17, 1755, there appeared an article signed simply, "C.M.," which suggested an electric telegraph. The writer's idea was to lay an insulated wire for each letter of the alphabet. The wires could be charged from an electrical machine in any desired order, and at the receiving end would attract disks of paper marked with the letter which that wire represented, and so any message could be spelled out. The identity of "C.M." has never been established, but he was probably Charles Morrison, a Scotch surgeon with a reputation for electrical experimentation, who later emigrated to Virginia. Of course "C.M.'s" telegraph was not practical, because of the many wires required, but it proved to be a fertile suggestion which was followed by many other thinkers. One experimenter after another added an improvement or devised a new application.

A French scientist devised a telegraph which it is suspected might have been practical, but he kept his device secret, and, as Napoleon refused to consider it, it never was put to a test. An Englishman devised a frictional telegraph early in the last century and endeavored to interest the Admiralty. He was told that the semaphore was all that was required for communication. Another submitted a similar system to the same authorities in 1816, and was told that "telegraphs of any kind are now wholly unnecessary." An American inventor fared no better, for one Harrison Gray Dyar, of New York, was compelled to abandon his experiments on Long Island and flee because he was accused of conspiracy to carry on secret communication, which sounded very like witchcraft to our forefathers. His telegraph sent signals by having the electric spark transmitted by the wire decompose nitric acid and so record the signals on moist litmus paper. It seems altogether probable that had not the discovery of electro-magnetism offered improved facilities to those seeking a practical telegraph, this very chemical telegraph might have been put to practical use.

In the early days of the nineteenth century the battery had come into being, and thus a new source of electric current was available for the experimenters. Coupled with this important discovery in its effect upon the development of the telegraph was the discovery of electro-magnetism. This was the work of Hans Christian Oersted, a native of Denmark. He first noticed that a current flowing through a wire would deflect a compass, and thus discovered the magnetic properties of the electric current. A Frenchman named Ampère, experimenting further, discovered that when the electric current is sent through coils of wire the magnetism is increased.

The possibility of using the deflection of a magnetic needle by an electric current passing through a wire as a means of conveying intelligence was quickly grasped by those who were striving for a telegraph. Experiments with spark and chemical telegraphs were superseded by efforts with this new discovery. Ampère, acting upon the suggestion of La Place, an eminent mathematician, published a plan for a feasible telegraph. This was later improved upon by others, and it was still early in the nineteenth century that a model telegraph was exhibited in London.

About this time two professors at the University of Göttingen were experimenting with telegraphy. They established an experimental line between their laboratories, using at first a battery. Then Faraday discovered that an electric current could be generated in a wire by the motion of a magnet, thus laying the basis for the modern dynamo. Professors Gauss and Weber, who were operating the telegraph line at Göttingen, adapted this new discovery to their needs. They sent the message by moving a magnetic key. A current was thus generated in the line, and, passing over the wire and through a coil at the farther end, moved a magnet suspended there. The magnet moved to the right or left, depending on the direction of the current sent through the wire. A tiny mirror was mounted on the receiving magnet to magnify its movement and so render it more readily visible.

One Steinheil, of Munich, simplified it and added a call-bell. He also devised a recording telegraph in which the moving needle at the receiving station marked down its message in dots and dashes on a ribbon of paper. He was the first to utilize the earth for the return circuit, using a single wire for despatching the electric current used in signaling and allowing it to return through the ground.

In 1837, the same year in which Wheatstone and Morse were busy perfecting their telegraphs, as we shall see, Edward Davy exhibited a needle telegraph in London. Davy also realized that the discoveries of Arago could be used in improving the telegraph and making it practical. Arago discovered that the current passing through a coil of wire served to magnetize temporarily a piece of soft iron within it. It was this principle upon which Morse was working at this time. Davy did not carry his suggestions into effect, however. He emigrated to Australia, and the interruption in his experiments left the field open for those who were finally to bring the telegraph into usable form. Davy's greatest contribution to telegraphy was the relay system by which very weak currents could call into play strong currents from a local battery, and so make the signals apparent at the receiving station.

IV

INVENTIONS OF SIR CHARLES WHEATSTONE

Wheatstone and His Enchanted Lyre—Wheatstone and Cooke—First
Electric Telegraph Line Installed—The Capture of the "Kwaker"—The
Automatic Transmitter.