Works by the same Author. 



SOUND. 



Fourth Edition, revised and augmented ; with Frontis- 

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The body of this work, dealing as 

 it does with the immovable truths of 

 acoustics, remains in the present edition 



aubstantially as it was in the former 

 editions. Various additions and cor- 

 rections have, however, been made to 

 the work. Brief descriptions of the 

 telephones of Bell and Edison, of the 

 microphone, and of the phonograph, are 

 introduced. Experiments are described 

 touching the action upon sound of soap- 

 bubbles filled with nitrous oxide and 

 hydrogen respectively. The effect of 



a change of velocity, as regards sound, 

 is thus rendered strikingly manifest, 

 while the student is helped to a clear 

 conception of the consequences of a 

 similar change in regard to light. The 

 observations on fog-signalhng described 

 in Lecture VII. have been somewhat 

 amplified, and rendered more intelligible 

 by the introduction of maps. The 

 stoppage of sound by a non-homogene- 

 ous atmosphere, and the consequent 

 production of aerial echoes, are also 

 further illustrated. 



LECTURES on LIG-HT DELIVERED in the 



UNITED STATES of AMERICA in 1872 and 1873. 

 Second Edition, with Portrait, Lithographic Plate and 59 

 Diagrams. Crown 8vo. price 7s. 6c?. 



NOTES of a COURSE of NIKE LECTURES 



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NOTES of a COURSE of SEVEN LECTURES 

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 delivered at the Royal Institution of Great Britain, 

 A.D. 1870. Crown 8vo. price Is. sewed, or Is. 6d. cloth. 



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RESEARCHES on DIAMAQNETISM and 



MAGNE-CRYSTALLIC ACTION ; including the Ques- 

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FARADAY as a DISCOVERER. 



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