The inventor asserts that the tube and diaphragm only act as resonators, and that the sounds produced by this instrument are nearly the same as those obtained from the ordinary string telephone: the tunes of a musical box were heard, and the reproduction of speech was perfect, both in intensity and in distinctness of sound; it even appeared that telephonic sounds were audible with the tin tube alone, surrounded by the helix. M. Wiesendanger says that ‘these different receiving telephones show clearly that the diaphragm and magnet are not essential, but merely accessory, parts of a telephone.’ VARIOUS EXPERIMENTS MADE WITH THE TELEPHONE. We must now consider a series of experiments which demonstrate the wonderful properties of the telephone, and which may also give some indication of the importance of the influences by which it is liable to be affected. _Experiments by M. d’Arsonval._--We have seen that the telephone is an extremely sensitive instrument, but its sensitiveness could scarcely be appreciated by ordinary means. In order to gauge it, M. d’Arsonval has compared it to the nerve of a frog, which has hitherto been regarded as the most perfect of all galvanoscopes, and it appears from his experiments that the sensitiveness of the telephone is two hundred times greater than that of the frog’s nerve. M. d’Arsonval has given the following account of his researches in the records of the Académie des Sciences, April 1, 1878: ‘I prepared a frog in Galvani’s manner. I took Siemens’ instrument of induction, used in physiology under the name of the chariot instrument. I excited with the ordinary pincers the sciatic nerve, and I withdrew the induced coil until the nerve no longer responded to the electric excitement. I then substituted the telephone for the nerve, and the induced current, which had ceased to excite the latter, made the instrument vibrate strongly. I withdrew the induced coil, and the telephone continued to vibrate. ‘In the stillness of night I could hear the vibration of the telephone when the induced coil was at a distance fifteen times greater than the minimum at which the excitement of the nerve took place; consequently, if the same law of inverse squares applies to induction and to distance, it is evident that the sensitiveness of the telephone is two hundred times greater than that of the nerve.