Abstract
IN August, 1880, I directed attention to the fact that thin disks or diaphragms of various materials become sonorous when exposed to the action of an intermittent beam of sunlight, and I stated my belief that the sounds were due to molecular disturbances produced in the substance composing the diaphragm (Amer. Assoc. for Advancement of Science, August 27, 1880). Shortly afterwards Lord Rayleigh undertook a mathematical investigation of the subject, and came to the conclusion that the audible effects were caused by the bending of the plates under unequal heating (NATURE, vol. xxiii. p. 274). This explanation has recently been called in question by Mr, Preece (Royal Society, March 10, 1881), who has expressed the opinion that although vibrations may be produced in the disks by the action of the intermittent beam, such vibrations are not the cause of the sonorous effects observed. According to him the aërial disturbances that produce the sound arise spontaneously in the air itself by sudden expansion due to heat communicated from the diaphragm, every increase of heat giving rise to a fresh pulse of air. Mr. Preece was led to discard the theoretical explanation of Lord Rayleigh on account of the failure of experiments undertaken to test the theory.
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References
Paper clx. in the Transactions of the Society, 1878. Vol. vii., pages 109, 168.
A paper read before the Philosophical Society of Washington, D.C., June 11, 1881, by Prof. Alex. Graham Bell .
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Upon a Modification of Wheatstone's Microphone and its Applicability to Radiophonic Researches 2 . Nature 24, 302–303 (1881). https://doi.org/10.1038/024302a0
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DOI: https://doi.org/10.1038/024302a0