The earliest attempts at the construction of an electric telegraph date back to a time long before the discovery of the electric current. As early as 1727 it was known that an electric discharge could be transmitted to a considerable distance through a conducting substance such as a moistened thread or a wire, and this fact suggested the possibility of a method of electric signalling. In 1753 a writer in _Scott’s Magazine_ brought forward an ingenious scheme based upon the attraction between an electrified body and any light substance. His telegraph was worked by an electric machine, and it consisted of twenty-six separate parallel wires, every wire having a metal ball suspended from it at each end. Close to each ball was placed a small piece of paper upon which was written a letter of the alphabet. When any wire was charged, the paper letters at each end of it were attracted towards the metal balls, and in this way words and sentences were spelled out. Many other systems more or less on the same lines were suggested during the next fifty years, but although some of them had considerable success in an experimental way, they were all far too unreliable to have any commercial success. With the invention of the voltaic cell, inventors’ ideas took a new direction. In 1812 a telegraph based upon the power of an electric current to decompose water was devised by a German named Sömmering. He used a number of separate wires, each connected to a gold pin projecting from below into a glass vessel filled with acidulated water. There were thirty-five wires in all, for letters and numbers, and when a current was sent along any wire bubbles of gas formed at the pin at the end of it, and so the letters or numbers were indicated. This telegraph, like its predecessors, never came into practical use. Oersted’s discovery in 1829 of the production of magnetism by electricity laid the foundation of the first really practical electric telegraphs, but little progress was made until the appearance of the Daniell cell, in 1836. The earlier forms of voltaic cells polarized so rapidly that it was impossible to obtain a constant current from them, but the non-polarizing Daniell cell at once removed all difficulty in this respect. In the year 1837 three separate practical telegraphs were invented: by Morse in the United States, by Wheatstone and Cooke in England, and by Steinheil in Munich. [Illustration: FIG. 26.--Dial of Five-Needle Telegraph.]