Pleasant ways in science / by Richard A. Proctor.

  • Proctor, Richard A. (Richard Anthony), 1837-1888.
Date:
1878
Catalogue details

Licence: Public Domain Mark

Credit: Pleasant ways in science / by Richard A. Proctor. Source: Wellcome Collection.

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    they inherit from savage and brutal ancestors. But here- after, when the representatives of the brutahty and savagery of our nature are held in proper disesteem, and those who have added new enjoyments to life are justly valued, a high place in the esteem of men will be accorded to him who has answered one half of the poet's aspiration, Oh for the touch of a vanished hand, And the sound of a voice that is still! Note,—Since the present paper was written, M. Aurel de Ratti has made some experiments which he regards as tending to show that there is no mechanical vibration. Thus, when the cavities above and below the iron disc of an ordinaiy telephone are filled with wadding, the instrument will transmit and speak with undiminished clearness. On placing a finger on the iron disc opposite the magnet, the instrument will transmit and speak distinctly, only ceasing to act when sufficient pressure is applied to bring plate and magnet into contact. Connecting the centre of the disc by means of a short thread with an extremely sensitive membrane, no sound is given out by the latter when a message is transmitted. Bringing the iron cores of the double telephone in con- tact with the disc, and pressing with the fingers against the plate on the other side, a weak current from a Daniell cell produced a distinct click in the plate, and on drawing a wire from the cell over a file which formed part of the circuit, a rattling noise was produced in the instru- ment. If these experiipents had been made before the phonograph was invented, they would have suggested the impracticability of con- stracting any instrument which would do what the phonograph actually does, viz., cause sounds to be repeated by exciting a merely mechanical vibration of the central part of a thin metallic disc. But as the phono- graph proves that this can actually be done, we must conclude that M. Aurel de Ratti's experiments will not bear the interpretation he places upon them. They show, nevertheless, that exceedingly minute vibra- tions of probably a very small portion of the telephonic disc suffice for the distinct transmission of vocal sounds. This might indeed be inferred from the experiments of M. Demozet, of Nantes, who finds that the vibrations of the transmitting telephone are in amplitude little more than l-2CX)Oth those of the receiving telephone.