The telephone may be heard at the same moment by several listeners, either by connecting the wires which unite the telephones in correspondence (near the receiving telephone) with branch wires of other telephones, which may be done up to the number of five or six, in short circuits; or by means of a little sounding-box closed by two thin membranes, one of which is fixed on the vibrating disk. When a certain number of acoustic tubes are connected with the membrane, Mr. M’Kendrick asserts that several people can hear distinctly. Telephones may also transmit speech to different stations simultaneously, by inserting them on the same circuit, and experiments made at New York showed that five instruments placed in different parts of the same telegraphic line could be made to speak in this way. In the telephonic experiments made on the canal lines in the department of the Yonne, it was ascertained that on a wire seven miles and a half in length, on which several telephones were placed at varying distances, three or four persons were able to converse with each other through the telephones, and each could hear what the other was saying. The questions and answers could be understood, even in crossing. It was also possible, by placing a telephone on a second wire, a little over five miles in length, and half a yard distant from the other, to hear the conversation exchanged on the first wire by following it to a distance not exceeding a mile and a quarter. Even the different voices of the two speakers could be distinguished. Since the telephone made its appearance in Europe, several inventors have asserted that they are able to make a telephone speak so as to be audible in all parts of a large hall. It has been shown that this was accomplished by Mr. Bell, and in this respect we do not see that those who have attempted to improve the telephone have attained results of greater importance. It is certain that the ordinary telephone can emit musical sounds which become perfectly audible in a tolerably large room, while the instrument is still attached to the wall. We should also remember the results obtained by MM. Pollard and Garnier in the experiments made at Cherbourg to connect the mole with the _Préfecture Maritime_.