_Experiments which may be made by anyone._--We will conclude this chapter, devoted to the account of the different experiments made with the telephone, by the mention of a singular experiment, which, although easily performed, has only been suggested a few months ago by a Pennsylvanian newspaper. It consists in the transmission of speech by a telephone simply laid on some part of the human body adjacent to the chest. It has been asserted that any part of the body will produce this effect, but according to my experience, I could only succeed when the telephone was firmly applied to my chest. Under such conditions, and even through my clothes, I could make myself heard when speaking in a very loud voice, from which it appears that the whole of the human body takes part in the vibrations produced by the voice. In this case, the vibrations are mechanically transmitted to the diaphragm of the sending telephone, not by the air, but by the body itself acting on the outside of the telephone. THE MICROPHONE. The microphone is in fact only the sender of a battery telephone, but with such distinctive characteristics that it may be regarded as an original invention which is entitled to a special name. The invention has lately given rise to an unfortunate controversy between its inventor, Mr. Hughes, and Mr. Edison, the inventor of the carbon telephone and the phonograph--a controversy which has been embittered by the newspapers, and for which there were no grounds. For although the scientific principle of the microphone may appear to be the same as that of Mr. Edison’s carbon sender, its arrangement is totally different, its mode of action is not the same, and the effect required of it is of quite another kind. Less than this is needed to constitute a new invention. Besides, a thorough examination of the very principle of the instrument must make us wonder at Mr. Edison’s claim to priority. He cannot in fact regard as his exclusive possession the discovery of the property possessed by some substances of moderate conductivity of having this power modified by pressure. In 1856, and often subsequently, as for example in 1864, 1872, 1874, and 1875, I made numerous experiments on this point, which are described in the first volume of the second edition of my ‘Exposé des applications de l’Electricité,’ and also in several papers presented to the Académie des Sciences, and inserted in their _Comptes rendus_. M. Clarac again, in 1865, employed a tube made of plumbago, and provided with a moveable electrode, to produce variable resistances in a telegraphic circuit. Besides, in Mr. Edison’s telephonic sender, the carbon disk, as we have seen, must be subjected to a certain initial pressure, in order that the current may not be broken by the vibrations of the plate on which it rests, and consequently the modifications of resistance in the circuit which produce articulate sounds are only caused by greater