1883.J Analyses oj Books. 487 
quickly. Few, if any, will be disposed to accept all the opinions 
contained in this book, but few if any thoughtful men can read it 
without advantage. 
Elementary Treatise on Physics, Experimental and Applied, for 
the use of Colleges and Schools. Translated and Edited 
from “ Ganot’s Elements de Physique.” By E. Atkinson, 
Ph.D., F.C.S. Professor of Experimental Science, Staff 
College, Sandhurst. Eleventh Edition, revised and enlarged. 
London : Longmans, Green, and Co. 
When the translator and editor of this book speaks of the “ con- 
tinued and still increasing favour” with which it has been re- 
ceived as a text-book for colleges and schools, and as a work of 
reference for the general reader, he does not in the least ex- 
aggerate. For a scientific treatise, necessarily somewhat costly, 
and containing nothing of a sensational character to reach eleven 
editions in twenty years is not a common occurrence, and proves 
certainly that the merits of the book must be very widely re- 
cognised among professors and teachers of physics. 
The present edition has been considerably enlarged, the ar- 
rangement of certain portions has been altered for the better', and 
the results of many investigations completed or extended since 
the appearance of the tenth edition have been duly inserted. 
Thus the chapter on the steam-engine has been re-written, a 
notice of Twaddell’s hydrometer, wanting in the French original 
has been inserted. The “ critical point” met with in the ex- 
periments on the liquefaction of gases has been explained more 
fully, and a good definition of “ vapours” in accordance with the 
present state of Science is supplied. An account of the relation 
between vapour densities and molecular weights has also been 
added. As might, perhaps, be expected the most important 
additions and revisions have been made in the books dealing 
with electricity. We find here a more complete account of 
secondary batteries, a notice of Pacinotti’s ring, and of the 
dynamo -electrical machines of Siemens and Brush. Under 
electro-dynamics we find important paragraphs added on 
mechanical units, electrical units, electrostatic units, electro- 
magnetic units, practical units, and on the relation of the electro- 
static to the electro-magnetic unit. 
A few passages only may seem to require revision. Thus on 
p. 3 we find a passage which might be construed as implying 
that hypothesis and theory were simply convertible terms. On 
p. hi we read an account of the phenomena occuring when 
dilute alcohol is kept in a bladder not in harmony with the most 
