Notices respecting New Books. 73 



drawings that a glass-cylinder electric machine bears to a plate- 

 glass machine of the ordinary kind will be more easily made, 

 and will probably be found preferable, when the dimensions are 

 not so great as to render it cumbrous. In it, it is proposed to 

 make the carrier-wheel nearly after the pattern of a mouse-mill, 

 with disks of vulcanite instead of wood for its ends. The 

 inductor and receiver of the rotatory electrophorus machine, 

 or the two inductor-receivers of the replenisher, may, when this 

 pattern is adopted, be mere tangent planes ; but it will probably be 

 found better to bend them somewhat to a curved cylindrical 

 shape not differing very much from tangent planes. When, 

 however, great intensity is desired, the best pattern will probably 

 be had by substituting for the carrier-wheel an endless rope 

 ladder, as it were, with cross bars of metal and longitudinal 

 cords of silk or other flexible insulating material. This, by an 

 action analogous to that of the chain-pump, will be made to 

 move with great rapidity, carrying electricity from a properly 

 placed inductor to a properly shaped and properly placed receiver 

 at a distance from the inductor which may be as much as several 

 feet. 



IX. Notices respecting New Books. 



Sound. A Course of Eight Lectures delivered at the Royal Institution 

 of Great Britain. By John Tyndall, LL.D., F.R.S. London : 

 Longmans and Co. 1867. (8vo, pp. xiii and 335.) 



WE hardly think that this work — excellent though it is in many 

 ways — will be entirely satisfactory to serious students of 

 science. To the reader who has once acquired a taste for the intel- 

 lectual pleasure which comes with real scientific knowledge, the 

 simple, unadorned, and unimpassioned style which aims at nothing 

 but clearness and accuracy, and which ordinary readers are apt to 

 find so dull and cold, is commonly far the most acceptable. The 

 true lover of science cares more to be told exactly what the pheno- 

 mena of nature are, and what are the conditions whereon their recur- 

 rence depends, than for even the most eloquent and poetical descrip- 

 tions of their beauty. He is conscious that if he can only know 

 them, their beauty will be evident enough. Nor does it move him 

 greatly when he is called upon to marvel at the wonders of science. 

 Nothing would astonish him so much as to find that the Truth of 

 Nature was really like what in his ignorance he fancied it, or was in 

 fact anything else than wonderful. 



But Professor Tyndall does not address exclusively or even princi- 

 pally those whose interest in science is already awakened. He says 

 that in this work he has "tried to render the science of acoustics 

 interesting to all intelligent persons, including those who do not 

 possess any special scientific culture." This sentence, we think, 

 justifies, as the titlepage explains, the presence in this book of a 



