Now, when a note is sounded in the box at the transmitting station, the membrane vibrates, and at each vibration the metal disc is separated from the point which it lightly touches when at rest. Thus contact is broken at regular intervals, corresponding to the rate of vibration due to the note. Suppose, for instance, the note _C_ is sounded; then there are 256 complete vibrations in a second, the electric current is therefore interrupted and renewed, and the bar of soft iron magnetized and demagnetized, 256 times in a second. Now, it had been discovered by Page and Henry that when a bar of iron is rapidly magnetized and demagnetized, it is put into vibrations synchronizing with the interruptions of the current, and therefore emits a note of the same tone as that which has been sounded into the transmitting box.
Professor Heisler, in his “Lehrbuch der technischen Physik,” 1866, wrote of Reuss’s telephone: “The instrument is still in its infancy; however, by the use of batteries of proper strength, it already transmits not only single musical tones, but even the most intricate melodies, sung at one end of the line, to the other, situated at a great distance, and makes them perceptible there with all desirable distinctness.” Dr. Van der Weyde, of New York, states that, after reading an account of Reuss’s telephone, he had two such instruments constructed, and exhibited them at the meeting of the Polytechnic Club of the American Institute. “The original sounds were produced at the furthest extremity of the large building (the Cooper Institute), totally out of hearing of the Association; and the receiving instrument, standing on the table in the lecture-room, produced, with a peculiar and rather nasal twang, the different tunes sung into the box at the other end of the line; not powerfully, it is true, but very distinctly and correctly. In the succeeding summer I improved the form of the box, so as to produce a more powerful vibration of the membrane. I also improved the receiving instrument by introducing several iron wires into the coil, so as to produce a stronger vibration. I submitted these, with some other improvements, to the meeting of the American Association for the Advancement of Science, and on that occasion (now seven years ago) expressed the opinion that the instrument contained the germ of a new method of working the electric telegraph, and would undoubtedly lead to further improvements in this branch of science.”