382 



NATURE 



[July 12, 1917 



or j>erhaps the instructions called for " harden at 

 a bright red and temper to a straw colour." It 

 was an art guarded with much secrecy and con- 

 fined chiefly to makers of tools. Pyrometers^ 

 structural changes, and a knowledge of the 

 thermal equilibrium diagram of the steel in ques- 

 tion were not even thought of. To-day it may 

 be said without exaggeration that modern 

 engineering practice at its best would be impos- 

 sible were it not based largely upon an art which 

 requires for its performance scientific knowledge, 

 skill, and judgment of a very high order. With 

 the exception of steels very low in carbon, there 

 is scarcely one — certainly no alloy steel — which 

 does not require a precisely 'defined heat treat- 

 ment, depending upon the purpose to which it is 

 to be put, if the best value is to be got out of 

 it. Of this the steels used in the automobile 

 industry furnish a conspicuous illustration. The 

 frame, the front and rear axles, the steering parts, 

 springs, crank-shafts, and gears, all have a more 

 or less severe duty to perform and require steels 

 possessing particular qualities of strength, tough- 

 ness, resilience, endurance, shock resistance, and 

 good wearing properties, which are obtained by 

 suitable heat treatment. 



Mr. BuUens has written a very serviceable book 

 on the above subject, of which the first edition 

 was quickly exhausted. The second edition, 

 which we have before us, is a reprint of the first, 

 with an appendix on the heat treatment of modern 

 high-speed tool steels. The opening chapters 

 deal with the testing and structure of steels, and 

 the operations of annealing, hardening, temper- 

 ing, and toughening. Then follow two on case- 

 carburising and case-hardening, which are 

 exceedingly good. The author has evidently- 

 studied Giolitti's researches with great profit to 

 himself and turned the knowledge gained to prac- 

 tical account. An interesting illustration of cast- 

 iron "growth " is furnished by his statement that 

 this is an unsuitable material for case-carburising 

 boxes, whereas malleable iron, soft steel, and 

 wrought iron can all be used. The next two 

 chapters, on the generation and application of 

 heatj are also very valuable, and show the 

 author's practical acquaintance with furnace 

 design, construction, and operation. 



The remainder of the book deals with the parti- 

 cular heat treatments in vogue for carbon and 

 alloy steels. Among the latter, nickel, chromium, 

 and nickel-chromium steels occupy an important 

 place. Indeed, nickel steels were the pioneers 

 among the alloy steels. Nickel was originally 

 added merely to give increased strength and 

 toughness over that obtained in ordinary rolled 

 structural steel. When heat treatments were also 

 applied they were found to enhance the valuable 

 qualities of the alloys to such an extent that they 

 soon came to hold, and still maintain, the premier 

 position in alloy-steel metallurgy. The conclud- 

 ing chapters deal with vanadium, manganese, 

 and silicon steels, and various types of tool steel. 



The book is one to be warmly commended ; it 

 is well written and, on the whole, very accurate in 

 its statements. H. C. H. C. 



NO. 2489, VOL. 99] 



SCHOOL AND PERSONAL HYGIENE. 



(i) Crowley's Hygiene of School Life. By 

 Dr. C. W. Hutt. Pp. XV + 428. (London: 

 Methuen and Co., Ltd.) Price 35. 6d. net. 



(2) Sylldbtis of Personal Hygiene for Colleges. 

 By Prof. E. C. Howe. Third revision. 

 Pp. 207. (Wellesley, Mass. : The Author.) 



(i) "PjR. CROWXEY having accepted an 

 ^-^ appointment in the Medical Department 

 of the Board of Education, the preparation of a 

 second edition of his "Hygiene of School Life " 

 has devolved upon Dr. Hutt, who has altered, 

 extended, and rewritten where necessary much 

 of the original work. Dr. Hutt has had the task 

 of selecting from a vast amount of material to 

 be found in official reports ; this he has performed 

 with good judgment, and his conclusions are 

 sound and convincing. 



The position taken in the book is that of the 

 administrator who is limited by the various enact- 

 ments dealing with the medical and hygienic 

 problems concerned with education, and such 

 subjects, therefore, as over-pressure, the curri- 

 culum, and the physiology of writing and of read- 

 ing have, perforce, to be omitted. The contents 

 include, in order, the physical condition of the 

 child, classification and groups of school children, 

 the infant and infants' schools, medical treatment 

 of school children, the provision of school meals, 

 baths, games and exercises, op>en-air education, 

 the school and infectious diseases, and the school 

 building. The book is illustrated with some 

 plates and a number of diagrams and plans, and 

 the price is exceedingly moderate. 



From the point of view of the administrator 

 who has to deal with things as they are, we do 

 not think that the student of school hygiene can 

 select a better guide than this second edition of 

 Crowley's "Hygiene of School Life." 



(2) Prof. Eugene Howe, of Wellesley College, 

 Mass., gives in this book a syllabus of a course 

 of personal hygiene suitable for the students of 

 a general educational institution. The course is 

 divided into thirty lectures. An abstract of each 

 lecture is given, and the right-hand pages are 

 left blank for notes by the student. At the end 

 of the book a bibliography is added, under the 

 various subjects dealt with, of works and papers 

 suitable for further study. The subjects seem to 

 be well chosen and the treatment of them satis- 

 factory. While presumably intended for Prof. 

 Howe's own students, those who may have to 

 give courses of lectures in p>ersonal hygiene to 

 lay audiences will find this book a suggestive and 

 useful guide. 



OUR BOOKSHELF. 



The Elementary Principles of Wireless Telegraphy. 

 By R. D. Bangay. Part ii. Second edition. 

 Pp. viii + 241. (London: The Wireless Press, 

 Ltd., 1917.) Price 25. 



The aim of this work is to explain the theory and 

 practice of wireless telegraphy to persons who do 



