October 14, 1920] 



NATURE 



209 



should' minimise the value of a text-book to 

 English students in schools, where the rest of 

 the curriculum has to be kept in mind by the 

 teacher. 



(2) Prof. Noyes's text-book is particularly in- 

 teresting- and suggestive, and very well got up, 

 with the exception of the illustrations. The treat- 

 ment is in general more concise than in the other 

 volume, but loses nothing in the way of clearness 

 and accuracy. It should prove a useful book to 

 teachers in the higher forms of schools who wish to 

 add to the interest of their lessons. The sum- 

 maries at the ends of the chapters will be found 

 useful in revision, and there are numerous sug- 

 gestive questions and exercises. The elements of 

 organic chemistry, in so far as they concern daily 

 life, are treated in a most interesting manner, 

 and the book should prove serviceable to students 

 of domestic science. 



It may fairly be said of both books that they 

 are of a higher order of interest and accuracy 

 than is usual in English books of the same 

 standard. There is too much tendency to follow 

 stereotyped lines in most cases in English books, 

 which no doubt results from a desire on the part 

 of the writers to conform to what they imagine 

 to be useful for examinational purposes. The 

 American writers as a whole are free from this 

 infirmity. J. R- P- 



Our Bookshelf. 



Moses: The Founder of Preventive Medicine. 

 By Capt. Percival Wood. (Biblical Studies.) 

 Pp. xi-t-ii6. (London: S.P.C.K. ; New York: 

 The Macmillan Co., 1920.) Price 4s. net. 

 Capt. Percival Wood is, of course, not the first 

 to recognise Moses as the founder of preventive 

 medicine, but he has marshalled his evidence in 

 an interesting and compelling manner in the 

 light of modern research. Thus he ascribes the 

 third plague that smote the Egyptians, that of 

 lice, as the indirect result of the first plague of 

 fouled water-supply, remarking that it does not 

 take long in a warm climate to become infested 

 with lice when personal hygiene is neglected. 

 The frogs, similarly, were driven on to the land 

 by the fouling of the water, and the myriads of 

 dead frogs tended to breed the flies of the fourth 

 plague. The lice and the flics and the rain, 

 together with the destruction of their crops by 

 locusts and hail, would likewise tend to engender 

 epidemic disease among the famine-stricken 

 Egyptians, and hence the culminating plague of 

 all, that of death (the selection of the firstborn 

 in the narrative is a dramatic detail added by a 

 later hand). 



The author passes in review the legislation on 

 hygiene and on the control of infectious diseases, 

 and the regulations regarding dietetics. Finally, 

 NO. 2659, VOL. 106] 



the diet of the Israelites during their wanderings 

 is considered. The nature of manna is problem- 

 atical. There was evidently a lack of proper food, 

 and the people probably suffered from deficiency 

 diseases — dwarfs, "broken-footed," and "crook- 

 backs " are mentioned, conditions that might 

 result from rickets. As a popular and accurate 

 description of an ancient system of hygiene this 

 book can be cordially recommended. 



R. T. H. 



Structural and Field Geology: For Students of 

 Pure and Applied Science. By Dr. James 

 Geikie. Fourth edition, revised. Pp. xxiv-i- 

 4544- Ixix plates. (Edinburgh : Oliver and Boyd; 

 London : Gurney and Jackson, 1920.) Price 

 24s. net. 



The demand for a fourth edition of this handsome 

 work is surticient testimony to its educational 

 value. The volume reflects the lucid teaching of 

 its author, and the present editor, Dr. Robert 

 Campbell, has found it desirable to make altera- 

 tions only in definitions and in descriptions of 

 minerals and rocks, in accordance with current 

 usage. Chemical formula;, which are so useful 

 in suggesting alliances among rock-forming 

 minerals, are still studiously avoided, except in 

 the case of simple oxides. This is surely now 

 unnecessary, when some knowledge of chemistry 

 must be required of all students of a scientific 

 subject. Though Dr. James Geikie expressly 

 stated that he did not write for specialists, a very 

 little more would have held the interest of the 

 reader. 



The great aim of the book, however, is the 

 realisation that rocks are to be studied out of 

 doors, and that structural geology is based upon 

 what the earth itself reveals. The selection of 

 full-page photographic illustrations, from those of 

 mountain-crests like Goat Fell to those of rock- 

 surfaces as they actually are seen in Nature, calls 

 us urgently to the field. Contrast the majestic 

 gloom of the Torridonian and Cambrian masses in 

 Plate Ixviii with the sunlit and periwinkled rocks 

 on the Arran shore in Plate xliii, and you perceive 

 the artist in the field-surveyor. It is a compliment 

 to the publishers, as well as to the memory of the 

 author, to say that this is a gift-book of a high 

 attraction. G. A. J. C. 



Notes Pratiques sur I'Observation Visuelle des 

 Etoiles Variables. Par Maurice E. J. Gheury 

 de Bray. Extrait de Ciel et Terre. (Published 

 by the .Author : 40 Wcstmount Road, Eltham, 

 S.E.g.) Price 2S. ^d. post free. 



The careful and persistent observation of variable 

 stars has risen from being the occasional hobby 

 of a few observers to one of the most important 

 branches of stellar physics, from which far-reach- 

 ing deductions have been drawn concerning star- 

 life, absolute magnitudes, and the structure of the 

 universe. The number of variables is now so 

 large that a considerable army of workers is re- 

 quired. The author s aim is to enlist recruits, 

 and the field of work that he recommends is that 



