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natur: 



[May 6, 1920 



fession. Prof. Lewes, who acted as chief assistant 

 to Prof. Debus for some years and eventually 

 succeeded to his chair, was no doubt fully 

 conscious of this' fact. At all events, his intimate 

 association with the young- officers in the labora- 

 tory must have afforded him abundant opportuni- 

 ties of learning it. When his turn came he entirely 

 remodelled the course of chemical teaching. 

 During the years of his assistaritship he had been 

 brought into frequent contact with Service and 

 dockyard problems, in which his chemical know- 

 ledge and practical aptitudes could be turned to 

 account. Prof. Debus was essentially the philo- 

 sophic student ; Prof. Lewes, with no pretensions 

 to the academic attainments of his predecessor, 

 was more a man of affairs, with a keen apprecia- 

 tion of the value of science to practice, and he 

 could bring his experience to bear upon the char- 

 acter and style of his teaching. 



The book before us was written to aid and 

 supplement Prof. Lewes 's instruction. It was 

 unique of its kind. It bore directly upon what he 

 conceived to be the true function of his chair. In 

 one sense it is more restricted in scope than the 

 ordinary text-book of pure chemistry, which seeks 

 to cover more or less fully every department of 

 the science, with no special reference to its prac- 

 tical application ; in another sense it is wider, 

 inasmuch as its subject-matter is intended to lead 

 up to the far-reaching problems with which 

 modern Service conditions deal. 



A book based upon such principles can con- 

 tinue to be of value only so long as it has regard 

 to the constant changes and increasing complexity 

 of these conditions. Each successive edition bears 

 witness that such regard has been held. The four 

 previous editions of the work were issued under 

 the direction of the original author, the fourth 

 having appeared in the year before the outbreak 

 of the war. 



The present edition — the fifth — is due to Prof. 

 Brame, Prof. Lewes 's successor at the Royal 

 Naval College. The plan of the work has not 

 been altered in any essential particular. But the 

 text has been carefully revised, and certain new 

 features have been introduced. Greater attention 

 has been paid to the applications of organic 

 chemistry, especially in relation to fuels, ex- 

 plosives, and oils, mineral and vegetable. Also, 

 the sections on boiler waters, corrosion, pigments, 

 etc., have undergone considerable alteration. 



It has become a truism to say that the great 

 war through which Europe has recently passed 

 was a chemist's war. Whether that is wholly 

 true is a matter of opinion. But it is at least uni- 

 versally acknowledged that chemistry entered more 

 largely into it than into any previous war. That 

 NO. 2636, VOL. 105] 



fact alone adds interest and value to a book of 

 this kind. Both arms of the Service now recog- 

 nise that the operations of modern warfare are 

 largely dependent upon chemical principles. That 

 dependence is bound to increase in the future, and 

 should therefore lead to a wider recognition of the 

 importance of chemical instruction to all who may 

 be concerned in the conduct of war, whether 

 afloat or ashore. The book before us makes 

 mention of many chemiqal applications and 

 adaptations which the war originated ; but the 

 complete story has yet to be told, and in the 

 present unsettled state of the world some time 

 must elapse before it can be published. When, 

 however, it is made generally known, it will con- 

 stitute a triumph for the knowledge, skill, and 

 resourcefulness of British chemists. That fact is 

 already appreciated in the Naval Service, and by 

 no section more warmly than by those who owe 

 their chemical knowledge to the instruction they 

 have received at the Royal Naval College. 



T. E. Thorpe. 



Euclid's Elements. 



Euclid in Greek. Booh I. With Introduction 

 and Notes. By Sir Thomas L. Heath. 

 Pp. ix-l-239. (Cambridge: At the University 

 Press, 1920.) Price io5. net. 



THE editor of this text expresses the hope that 

 it may be read by boys in the higher forms 

 of schools. We hope so too, although the price 

 of the book is rather prohibitive. At any rate, a 

 copy should be obtained for the school library. 



The text is accompanied by an introduction and 

 a set of explanatory and critical notes; each of 

 these is a model of its kind. In the introduction 

 we have a summary of the contents of the 

 elements, all the facts known about Euclid's life 

 and works, and a full account of the principal 

 translations and editions of the elements. The 

 notes are extremely valuable in various ways. In 

 the first place, the author is both a competent 

 Greek scholar, and also a student imbued with 

 the unadulterated spirit of Greek geometry. This 

 makes his translations of technical terms emin- 

 ently apt and trustworthy. As an example of his 

 critical ability, we may take his discussion of the 

 very difficult phrase i$ tcrov in Euclid's defini- 

 tion of a straight line. He shows, we think con- 

 clusively, that the intention of the definition is 

 to express that if any point on the (indefinite) 

 line be taken, what we may call the aspect of 

 the line therefrom is an " indifferent " one, with 

 no bending one way or the other; in fact, we 

 have an attempt at expressing in abstract terms 

 the Platonic test — that a straight viewed "end 



