The sender nearly resembles the one we have previously described, except that, when it is used for musical sounds, a platinum point is employed instead of the disk of carbon, and it ought not to be in constant contact with the vibrating plate. According to the ‘Telegraphic Journal,’ it consists simply of a long tube, two inches in diameter, having one end covered with a diaphragm formed of a thin sheet of copper, and kept in its place by an elastic ring. A small platinum disk is riveted to the centre of the copper diaphragm, and a point of the same metal, fitted with a firm support, is adjusted before the disk. When the singer stands before the diaphragm, its vibration causes it to touch the platinum point, and produces the number of breaks in the current which corresponds to the vibration of the notes uttered. The experiments lately made in America, in order to decide on the merits of various telephonic systems, show that Mr. Edison’s telephone gives the best results. The ‘Telegraphic Journal,’ May 1, 1878, states that on April 2 Mr. Edison’s carbon telephone was tested between New York and Philadelphia on one of the numerous lines of the West Union. The length of the line was 106 miles, and ran parallel to other wires almost throughout its length. The effects of induction caused by telegraphic transmissions through the adjacent wires were enough to make speech inaudible through the other telephones, but they had no influence on Edison’s telephone, which was worked with a battery of two cells and a small induction coil, and Messrs. Batchelor, Phelps, and Edison were able to converse with ease. Mr. Phelps’ magnetic telephone, which is considered to be the most powerful of its kind, did not afford such good results. In the experiments made between the Paris Exhibition building and Versailles, the jury commission was able to ascertain that the results were equally favourable. _Telephones by Colonel Navez._--Colonel Navez of the Belgian Artillery, inventor of the well-known balistic chronograph, has endeavoured to improve the Edison telephone by employing several disks of carbon instead of one. He considers that the variations of electric resistance produced by carbon disks under the influence of unequal pressure depend chiefly on their surface of contact, and he consequently believes that the more these surfaces are multiplied, the greater the differences in question will be, just as it happens when light is polarised through ice. He adds that these disks act well by their surfaces of contact, since, if they are separated by copper disks, the speech reproduced ceases to be articulate.[6]