In 1891, Professor Branley found that the electric vibrations in ether could be detected by means of fine metallic filings. No matter how good a conductor of electricity the metal in mass might be, when reduced to fine filings or powder it offered powerful resistance to a passing current; in other words, became a very poor conductor. An electric discharge or spark near the filings greatly decreased their resistance. If the filings were jarred, their original resistance was restored. Branley placed his filings in a tube, into either end of which wires were passed. These were connected with a galvanometer. Ordinarily, the resistance of the filings was such as to prevent a current passing through them, and the galvanometer remained unaffected. But when an electric spark was emitted near the tube, the resistance was so much decreased that the current passed readily through the filings, and was detected by the galvanometer. This is simply equivalent to saying that the discharge of the electric spark made the filings to cohere and become a better conductor than when lying loosely in the tube. Here, then, was opportunity for an instrument which had but to regulate the number of sparks and indicate the presence of the electric waves in order to produce dots and dashes similar to those used in the common telegraph. Such an instrument was brought nearest to perfection by Signor Marconi, a young Italian, in 1896. With it he succeeded in sending electric waves through ether or space, and without the use of wires, a distance of four miles, upon Salisbury Plain, England. Later, he transmitted messages by means of space (wireless) telegraphy across Bristol Channel, a distance of 8.7 miles, and subsequently across the English Channel, a distance of 18 miles. Mr. W. J. Clarke, of America, has improved upon Marconi’s methods of space telegraphy, and shown some remarkable results. Whether space telegraphy will eventually supersede that by wires is one of the problems that time only can solve. But such are the possibilities of electrical science that we may well be prepared for more wonderful revelations than any yet made. [Illustration: THE GREAT EASTERN LAYING AN OCEAN CABLE.] IV. HELLO! HELLO! Telegraph (Gr. _tele_, far, and _graphein_, to write) implies the production of writing at a distance by means of an electric current upon a conductor. Telephone (Gr. _tele_, far, and _phone_, sound) implies the production of sound at a distance by the same means, though the word telephone was in early use to describe the transmission of sound by means of a rod or tightly stretched string connecting two diaphragms of wood, membrane, or other substance. This last plan of transmitting sound came to be known as the string telephone, and it retained this name until the invention of the electric telephone.