342 SCIENCE PROGRESS 



edition, the appendix, written at an earlier date, containing theorems on centres of 

 gravity, is omitted here. 



The book is, on the whole, well translated and has a useful index. Such things 

 as "alright" (p. 71) and "to thoroughly understand" (p. 283) are only, apparently, 



shocking to British eyes or ears or both. 



Philip E. B. Jourdain. 



PHYSICS 



A Text-Book of General Physics, Electricity, Electromagnetic Waves, and 

 Sound. By J. A. Culler, Ph.D. [Pp. x + 321.] (Philadelphia: 

 J. B. Lippincott Company. Price ys. 6d. net.) 



THE author states in the preface that he had, while preparing the book, three 

 aims in view : (1) lucidity of description, etc., to the average student, (2) emphasis 

 on the physical side of physics and some account of commercial applications, 

 (3) incorporation in the body of the discussions and in their proper place, of the 

 electronic and electromagnetic theories. 



It is, of course, a matter of personal judgment as to what is the proper place 

 in the development of a subject for the introduction of a particular theory ; but it 

 is certainly a novel procedure to begin a text-book with a discussion on " What 

 Electricity is," and follow up with " Evidence for the Electron Theory," and an 

 account of J. J. Thomson's and Lenard's experiments on kathode rays. One 

 thing must be taken for granted in such a beginning, viz. that the average student 

 whom the author has in mind is no mere beginner, and even so, it is still doubtful 

 if the author is producing, as he claims in the preface, a " logical development of 

 the live topics which, it seems, should be included in a text-book for college 

 students." Exception could be taken on the same grounds to his introduction of 

 electrons almost at the outset of the sections dealing with magnetism. It seems 

 to the writer of this notice that a logical development requires the very opposite 

 procedure to that adopted by the author. As he himself remarks, " the electron 

 theory is not the result of a sudden discovery, but rather a growth from the 

 accumulated evidence of years of experiment." Does that fact alone, then, not 

 demand in an explanatory manual a fairly complete account of those experiments 

 at the outset, so that the student may grasp the strength of the evidence on which 

 the electron theory is based ? 



However, in other respects the author effects his purpose with considerable 



success. By omitting a good deal of the mathematical work usually introduced 



into manuals of this type, he finds room for lucid and interesting accounts of 



commercial and technical applications, and certainly makes his book strong on 



the " physical side of physics " in the sense that he devotes more space to the 



description of parts and dimensions of various types of apparatus than to the 



mathematical theory of their functioning. The subject of Electromagnetic Waves 



is introduced well on in the book, and serves, as it were, as a preface to a brief 



account of Physical Optics — too brief in the writer's opinion, considering the 



importance of that branch of physics. A short and well-written account of the 



essential phenomena of sound concludes the volume. 



J. Rice. 



Experimental Electricity and Magnetism. By M. Finn, M.Sc. [Pp. x + 436.] 

 (London : G. Bell & Sons, 191 5. Price 4^. 6d. net.) 



This is a book of quite a different type. It is intended for beginners, and not 

 only deals with the matter usually taught in schools up to Matriculation standard, 



