Since this paper by Mr. Edison appeared in June 1878, he has applied the phonograph to several other purposes, among which we may mention that of registering the force of sounds on railways, and especially on the metropolitan atmospheric railway in New York. The instrument which he has made for this purpose resembles that by Mr. Leo Scott, and bears the same name. It is described and represented in the ‘Daily Graphic’ of July 19, 1878, as well as the aerophone, the megaphone, and the microtasimeter, which is adapted for astronomical observations. We should exceed the limits laid down for this volume, if we were to give a more detailed account of these inventions. M. Lambrigot, one of the officials on the telegraphic lines in France, and the author of various improvements in the Caselli telegraph, has shown me a phonographic system of his own invention in which it is reduced to its simplest form. He sent me the following description of his system. ‘The instrument consists of a wooden slab placed vertically on a stand and firmly fixed upon it. There is a round opening in the middle of the slab, covered by a tightly stretched sheet of parchment bearing a steel knife, which, like the tracing point of the phonograph, is intended to trace the vibrations. A solid block rises from the stand to the middle of the slab, and supports a slide on which a runner can move in front of the slab. There is a strip of glass on this runner, of which one side is covered with stearine. When the runner is moved to and fro, the stearine comes in contact with the knife and takes the mould of its form, which is curved throughout. ‘A sound places the sheet of parchment in vibration, and imparts its movement to the knife, which traces various lines on the surface of the stearine. ‘The reproduction thus obtained on the strip of glass is subjected to the ordinary processes of metallisation. By galvanism a deposit of copper is obtained which reproduces the lines in an inverse way. In order to make the metallic plate speak, it is necessary to pass a point of ivory, wood, or horn lightly over the signs, and, by moving it more or less quickly, the different tones can be heard, just as they were spoken. ‘Since copper is relatively harder than lead, the copper plate on which the vibrations are traced will afford an unlimited number of reproductions. To obtain this result, a lead wire must be applied to the plate, and due pressure must be exerted on it. The wire is flattened and takes the impression of all the traces which then appear in relief. If the edge of a card is passed through this impressed tracing, the same sounds are produced as those which are obtained from the copper plate.’