42 Curiosities of Sound. 



could only notice very slight changes. A great eruption even 

 of Vesuvius would produce no other effect than to diminish 

 slightly the depth of the semicircular trench of the Atrir del 

 Cavallo, and to change its colour. Seen from the moon, such 

 an alteration would appear problematical, and would give rise 

 to discussions amongst observers. The observations made by 

 P. Secchi on the 10th and 11th of February last ( ff Comptes 

 E-endus," 25th February), tend materially to the belief that 

 some change of this sort must have been produced in the con- 

 figuration of the crater Linne, since the date of Lohrmann's 

 and Beer and Madler's maps. Moreover, it is to be desired 

 that observations relating to the absolute permanence, or to 

 very slight alterations on the moon's surface, should be multi- 

 plied, for a single change, however slight, would suffice to 

 show that a geological life exists in the interior of the moon, 

 as well as in the interior of the earth. 



CURIOSITIES OF SOUND* 



Peopessoe Tyndall's lectures on sound are, in their way, as 

 admirable as the lectures on heat, which formed the foundation 

 of his well-known work, ' ' Heat as a Mode of Motion," though 

 in dealing with the aerial vibrations which act upon our 

 auditory nerves he has chiefly had to expound the discoveries 

 of others, while in discussing the phenomena of heat it was 

 his happy task to record many brilliant discoveries of his own. 

 We are very glad that he has used plain English on his title- 

 page; a book on "Sound" promises to be intelligible and 

 interesting, while a treatise on acoustics would look alarming 

 and dry. All through the work before us we meet with indi- 

 cations of the learned professor's remarkable aptitude for 

 presenting his subject in a simple and elegant form, and it is 

 gratifying to be assured that the present book will do far more 

 than has been accomplished by any preceding publication to 

 popularize a branch of science that has suffered much neglect, 

 from the erroneous impression that it was too abstruse for 

 ordinary minds. 



A world without sound would seem a dismal solitude to 

 those who are familiar with human voices, the notes of birds, 

 the cries of animals, the hum of insects, and the multitudinous 

 noises of active life. What wo call the silence of night and 

 of waste places, and which, for a brief period, yields the 



* " Sound :" a Course of Eight Lei'tures, delivered at the Royal Institution of 

 Great Britain, by John Tyndall, LL.D., F.R.S., Professor of Natural Philosophy 

 in the Royal Institution, and in the Ivoyal School of Mines. Longmans. 



