December 30, 1909] 



NATURE 



245 



ci practical point of view, of immense importance. 

 Tliese are, however, minor blemisfies of the author's 

 work ; the important thing is that he has given us 

 an eminently useful and readable book on a subject 

 which has too long been neglected in this country. 



The second part of the volume under review deals 

 in great detail with the leakage of induction motors 

 and its predetermination. It is a careful investigation 

 of all the different items which influence leakage, 

 power factor, and overload capacity. The subject is 

 highly technical, and will, therefore, mainly interest 

 the designers of induction motors. Specialists in this 

 branch will, however, find the author's method of 

 dealing with the question of leakage, and especially 

 his diagrams and tables, very useful. 



GiSBERT KaPP. 



OVR BOOK SHELF. 

 Practical Microscopy. .-In Introduction to Micro- 

 scopical MetMods. By F. Shillington Scales. Second 



Edition. Pp. xvi + 334. (London: Baillifere, Tindall 



and Cox, 1909.) Price 5^-. net. 

 Although nominally this is a second edition of 

 Mr. Scales 's "Elementary Microscopy," published in 

 1905, yet it is in effect a new book. The first edition 

 was not so pretentious, and did not attempt to give 

 so much information on widely varying branches of 

 microscopy; in fact, if any criticism may be offered, 

 it is that now too much is attempted. 



The actual practical instruction in the use and 

 manipulation of the microscope is particularly lucid, 

 and it is difficult to imagine that it could be expressed 

 more clearly. The theoretical side is practically un- 

 touched, perhaps wisely so, as to have gone into the 

 theorv with sufficient fulness to have n'^ade it 

 intelligible to the ordinary reader would have entailed 

 a great increase in the amount of matter. 



The subject of photomicrography has been touched 

 on, and this constitutes an entirely new chapter in 

 tlie book, as in the first edition no attempt was made 

 to deal with it at all. The instructions given are 

 clear, but are in some respects not so full as an earnest 

 student would desire. 



The recentlv re-introduced methods of dark ground 

 illumination are described, and practical instructions 

 are given in the use of typical illuminators. The 

 various methods of illumination of opaque objects are 

 fully dealt with, both by means of an ordinary 

 condensing lens used in conjunction with low powers 

 and bv vertical illuminators for use with high powers. 



In general, the book may be commended to any 

 student who requires to use the microscope for 

 ordinary laboratory purposes or for research, as one 

 that will afford him all the practical assistance he is 

 likely to require in the course of his work. 

 Erosion of the Coast and its Prevention. By 



F. W. S. Stanton. Pp. 68. (London : St. Bride's 



Press, Ltd., n.d.) Price 3^. net. 

 This book is a reprint of a series of articles which 

 recently appeared in Public Works. 



It consists of five "parts," or chapters, relating 

 respectivelv to general observations on coast erosion ; 

 the agents of destruction and construction, and their 

 effects on the English coast; land reclamation and 

 coast defence ; with an appendix on the Thames 

 estuary. There are several maps showing the coast 

 of England and illustrations of defence works. The 

 maps appear to have been reproduced from larger 

 drawings, the writing and names of places being so 

 diminished and indistinct as scarcely to be legible, even 

 with the aid of a magnifying glass. 

 NO. 2096, VOL. 82] 



The contents of the book form an interesting sum- 

 mary of the condition of coast erosion and protection 

 in England, suitable for a serial publication, but they 

 are of too general and superficial a character to be 

 of any use as a text-book on the subject, and contain 

 no information of consequence that has not been more 

 fully dealt with in books already published. The 

 author does not appear to have made any use of the 

 information contained in the evidence laid before the 

 Coast Erosion Commission, and the fact of this 

 commission being in existence is only once casually 

 mentioned. 



The author attributes the destruction of the coast, 

 amongst other agencies, to the action of undercurrents 

 below low water, and of submarine springs and 

 "animal borers," and states that the consideration of 

 such agents of destruction "leads to feelings approach- 

 ing despair," and "bordering on consternation when 

 the formation of the coast consists of glacial deposit, 

 the London Clay and the like." It would have been 

 more satisfactory if this theory had been supported 

 by instances where this occurs. Although it is also 

 stated that this class of erosion is beyond prevention, 

 in another part of the book a solution of the difficulty 

 is described as being effected by means of submerged 

 chain cable groynes, and it is stated, on the authority 

 of the inventor of this scheme, that these groynes have 

 been laid on flat, sandy shores with excellent results. 

 The locality where this has been done is not given, nor 

 anv particulars as to the condition of the shore before 

 and after their use. 



The Evolution of the Sciences. By L. HouUevigue. 

 Translated from the French. Pp. 31S. (London: 

 T. Fisher Unwin, iqog.) Price 6s. 6d. net. 

 In his preface to the English edition of his book, M. 

 HouUevigue explains that it is not his object to teach 

 men of science anything. " I only wish," he writes, 

 "to interest those who love science as outsiders in the 

 general ideas which form the atmosphere of the labora- 

 torv, and, above all, to make them familiar with that 

 superior form of common sense which is called the 

 scientific spirit." Nine subjects are dealt with — the 

 tendencies of chemistry, transmutation and Sir \\'illiam 

 Ramsav's experiments, the existence of matter, the 

 interior of the earth, the sun, eclipses, the Milky Way, 

 the organisation of matter, and the frontiers of the 

 sciences. Each essav presents the broad aspects of 

 the subject surveved, and is well calculated to set 

 students thinking' about fundamental principles of 

 science. Judging from the absence of reference to 

 work bv jolyon" radio-activity in relation to the age 

 of the earth. Hale on his solar observations, Kapteyn 

 and Eddington on star-drifts, and other researches of 

 recent vears connected with the subjects described, the 

 author' has not kept in close touch with all the points 

 in which progress is now being effected. 



History of .Astronomy. By Prof. G. Forbes, F.R.S. 



Pp. 'ix+154; illustrated. (London: Watts and Co., 



1909.) Price IS. net. 

 In this small volume Prof. Forbes describes the evolu- 

 tion of astronomical knowledge under three periods — 

 the geometrical, the dynamical, and the physical. In 

 addition, in book iii. he also describes the evolution 

 of the instruments which have enabled astronomers of 

 all ages to contribute to the store of knowledge on 

 which our present-day astronomy is based. 



The geometrical period covers the ages which 

 elapsed "between the time when man simply "won- 

 dered " and the time when his collected observations 

 and knowledge had prepared the way for Kepler. This 

 is a verv interesting section, in which the methods 

 and idea's of earlv astronomers are so clearly explained 

 as lo (Jernand the attention of the general reader. 



