Great Facts / A Popular History and Description of the Most Remarkable Inventions During the Present Century

by Frederick C. Bakewell

The first near approach to the needle telegraph, now used in this country, was made by Baron de Schilling, who, in 1832, constructed at St. Petersburg an electric telegraph consisting of five magnetic needles. This may be considered as the precursor of the five-needle telegraph, first patented by Professor Wheatstone in 1837. By the separate deflection of those needles to the right hand or to the left, by reversing the connections with the poles of the batteries, ten primary signals could be obtained; and by bringing two into action at the same time, many more signals might be made than were required for indicating the letters of the alphabet, and they could be appropriated to express several words. For the action of this very efficient telegraph only five wires were required, and the signals being all primary ones, the messages might have been transmitted very quickly.[6] In a subsequent modification of the telegraph, he contrived to make all the signals with one magnetic needle alone, by repeating the deflections to the right and to the left, as done in the needle telegraph now generally used in England.

Another step made by Baron de Schilling was the invention of an alarum to call attention when a message was about to be sent. Some contrivance of this kind was considered essential in the early days of the practical application of the Electric Telegraph, as no one then contemplated that telegraphic communications would be so frequent as to require a person to be always near the instrument, waiting for the receipt of messages.

Baron de Schilling's alarum was very simple. One of the magnetic needles acted as a detent which held a weight suspended, and when the needle was deflected, the weight fell upon a bell. The alarums subsequently invented were constructed on the same principle, but instead of employing one of the magnetic needles as a detent, an electro-magnet was used for the purpose, and clock mechanism was introduced to sound a bell continuously, as soon as it was set in action by the withdrawal of the detent. At the present time alarums are not used in the regular stations of the electric telegraph companies; the sound of the needles, as they strike against the ivory rests on each side, being sufficient to call the attention of the clerks, who are in constant attendance.

We have hitherto been enabled to trace, step by step, the advances made at intervals—years asunder—in bringing the Electric Telegraph into practical use; but we are now approaching a time when it becomes difficult to enumerate, and impossible to describe within reasonable compass, the numerous inventions that were patented and otherwise made known for giving greater efficiency to that means of communication.

In the early part of the year 1837, the electric telegraphs of Mr. Alexander, of Edinburgh, and of Mr. Davy, were publicly exhibited in London, and excited much attention; though, at that time it was not supposed that it would be possible to make use of that means of communication for general purposes. Mr. Alexander's telegraph was the same in principle as those of M. Ampère and of Baron de Schilling, though in some respects not so efficient as either, for its action was slow, and it required a separate wire for each letter of the alphabet. It was considered a great advantage of this telegraph at the time, that it exhibited actual letters of the alphabet, instead of symbols. This was effected by having the twenty-six letters painted on a board, and concealed from view by a number of small paper screens, which were attached to magnetic needles. When any of the needles was deflected by sending an electric current through the surrounding coil, the screen was withdrawn and exposed the letter behind. Twenty-six keys, resembling those of a pianoforte, were ranged in connection, one with each wire, and on pressing down any one of the keys, contact was made between the battery and the wire connected with its associated magnetic needle; and in this manner, messages might easily be transmitted and read. The objections to this telegraph, in the form in which it was exhibited, were not only the impracticability of laying down and insulating so many wires, but the paper screens attached to the needles impeded their action, and rendered the transmission a very slow process. It is questionable, indeed, whether that telegraph could have been worked at all through a circuit of many miles.

Mr. Davy's telegraph was similar to that of Mr. Alexander's, though much more compact and better arranged. The letters were painted on ground glass, lighted behind, so that when the screens were withdrawn the letters were seen in transparency.

Professor Wheatstone, who had for some previous years been endeavouring to perfect a practical electric telegraph, took out his first patent in 1837. It closely resembled in general features the telegraph of Baron de Schilling. It consisted of five magnetic needles, ranged side by side on a horizontal line that formed the diameter of a rhomb. The needles were suspended perpendicularly, being kept in that position by having the lower ends made slightly heavier than the upper. The rhomb was divided into thirty-six equal parts by ten cross lines, and the needles were placed at the points where the lines intersected, as shown in the diagram.