Sound / by John Tyndall.

  • Tyndall, John, 1820-1893.
Date:
1883
Catalogue details

Licence: Public Domain Mark

Credit: Sound / by John Tyndall. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

    474/494 (page 450)
    Note. June 3.—I annex here a sketch of an apparatus devised by my assistant and constructed by Tisley and Spiller, for the demonstration of the law of reflection of sound. It consists of two tubes (af, br), with a source of sound at the end E of one of them, and a sensitive fiame at the end f of the other. The axes of the tubes converge upon a mirror m, and they are capable of being placed so as to enclose any required angle. The angles of incidence and reflection are read off on the gradu- ated semicircle. The mirror m is also movable round a vertical axis. Remarkable Instances of Acoustic Opacity. For the following account of the battle of Gain's Farm, 1 am indebted to the Rector of the University of Virginia :— ' Lynchburgh, Virginia : 'March 19, 1874. ' Sir,—I have just read with great interest your lecture of •January 16, on the acoustic transparency and opacity of the sound was subsequently found able to penetrate two hundred layers of cotton net ; a single layer of wetted calico being competent to stop it. Lord Kayleigh, for whose judgment I have the greatest respect, has questioned the foregoing explanation of the phenomena recorded 1 >v Arago. Whatever becomes of the explanation, the facts above recorded will stand, and for their sake I retain the paper.