November 3, 1910] 



NATURE 



OUR BOOK SHELF. 



Household Foes. A Book for Boys and Girls. By 

 Alice Ravenhill. Pp. xxiii + 359. (London : Sidg- 

 wick and Jackson, Ltd., 1910.J Price 2s. 6d. 



Miss Ravenhill has written this small work with the 

 bject of arousing the interests of boys and girls in 

 :\e practice of daily domestic cleanliness, and at the 

 ime time of furnishing them with reasons for this 

 : actice. She also aims at indicating the links which 

 .aould be made to connect school lessons with home 

 habits, and prominence is given to the value of good 

 habits and to the necessity for their constant daily 

 practice. She directs attention to the broad educa- 

 tional value of the subject of '"hygiene," in exercising 

 observation and reason, and in cultivating the habit 

 of tracing effects to their causes. The text of most 

 : the chapters is "dirt"— the dirt of home surround- 

 ;.gs, of air, water, and food; and at the end of each 

 chapter references are given to works in which the 

 subject-matter may be further studied and developed, 

 ore especiallv on the practical and experimental 

 de. Young people are slow to learn that there are 

 no rights apart from responsibilities, which in this 

 connection include duties to self, to home, to com- 

 munitv, to empire, and to race; it is well, therefore, 

 that Miss Ravenhill devotes her two concluding 

 chapters to "the citizen's power to control dirt, decay, 

 and disease," and "imperial safeguards against dirt 

 and disease." 



Hygiene has gradually found a footing in the 

 elementary school code ; but one cannot hope, for 

 some years to come, to get the best results of this 

 teaching and training, for the reason that school 

 teachers as a body do not possess the necessar^f know- 

 ledge to enable them to present the subject with judg- 

 ment and discrimination. This small work well 

 serves as a ven,- useful guide to them, and to this end 

 it is perhaps the best statement hitherto published, 

 for the essential facts are dealt with in an appropriate 

 and impressive manner, and the book contains little 

 (if anything) which is unsuitable or unnecessary, while 

 the authoress tells practically all that it is necessary 

 to tell. A child with the elementary- knowledge of 

 hygiene which Miss Ravenhill seeks to convey, and 

 trained to act in accordance with its precepts, should 

 be well equipped from the standpoint of hygiene. The 

 book may be confidently recommended to all those 

 parents and teachers who are concerned with the 

 . education of the young. 



History of Chennstrw By Sir Edward Thorpe, C.B., 

 F.R.S. Vol. i.. From the Earliest Times to the 

 Middle of the Nineteenth Century. Pp. viii+148. 

 Vol. ii.. From 1850 to 1910. Pp. viii+152. (Issued 

 for the Rationalist Press Association, Ltd.) 

 (London : Watts and Co., 1909 and 19 10.) Price 

 \s. net each volume. 



Sir Edward Thorpe, who has enriched chemical 

 literature with so many valuable biographical contri- 

 butions, has added greatly to our indebtedness bv the 

 publication of these two' small volumes of chemical 

 histor}-. In method and st\le thev follow the emin- 

 ently readable work of Thomas Thomson, which has 

 been so long out of print, and in many respects out 

 of date, and the modern student is now' supplied with 

 a brief history- of chemistr>% which is well within his 

 intellectual and material means, and cannot fail 

 to add greatly to the interest of his studies. The 

 divorce of historical and other human interest from the 

 study of science, resulting from our examination svstem, 

 is greatly to be deplored. It gives good ground for the 

 allegations of ariditv so often made against scientific 

 teaching and scientific text-books, and it deprives the 

 NO. 2140, VOL. 85] 



student of much that would aid him in the comprehen- 

 sion of modern chemical theory. It is to be hoped 

 that these volumes will have a very wide circulation, 

 and that students may be encouraged to proceed to 

 study some of the works which are indicated in the 

 appended bibliographies. 



The first volume, beginning with the chemistr>- of 

 the ancients, brings the reader to the early part of 

 the nineteenth centur\-, whilst the second volume 

 follows the subject to the present day. This last 

 volume is naturally highly compressed, but, like the 

 first, it bears the imprint of a master-hand in the 

 exact and readable presentation of chemical history. 

 A series of admirable portraits is inserted throughout 

 the work. A. S. 



A Course of Elementary Science, Practical and De- 

 scriptive. By John Thornton. Pp. vi + 216. 

 (London : Longmans and Co., 1910.) Price 25. 



This book, which contains chapters on measurement, 

 mechanics, and heat, is intended by the author for 

 junior pupils who are attending class and laboratory 

 instruction. As the title implies, it is partly descrip- 

 tive and partly practical in character. After perusing 

 the book one is led to the conclusion that the author 

 has not a very wide acquaintance with physics or 

 much experience of up-to-date laboratory methods. 

 The book has the characteristic of those many manuals 

 on this subject which appeared so hurriedly ten or 

 twelve years ago. The language is often loose, e.g. 

 p. i;^, Expt. I, "Draw a large circle on a sheet of 

 cardboard and divide it into degrees." On p. 29 the 

 author states that results need not be carried beyond 

 the second decimal place as a rule. In determining 

 quantities in the laboratory' where the final result is 

 obtained by arithmetical operations on quantities 

 actually measured, it is the degree of accuracy with 

 which these several quantities are measured that 

 determines the number of significant figures in the 

 final answer. Such examples as Expt. 11, p. 35 : — 

 Weight of lead in air, 17 oz. ; weight of lead in water. 

 155 oz. ; specific gravity, ii'3 ; or the example on 

 p. 41 : — 3ooo/o'8.; = 35294 c.c, are ill-chosen. On 

 p. 131 we are told that the steel rails of a tram line 

 have a small space left between their ends, when 

 laid, to allow for expansion. How many observant 

 boys have looked for such spaces and failed to find 

 them? On p. 144 it is stated that water expands 

 regularly from CM-dinan,' air temperature to 100° C. 



The Brooks Patent T-square Lock. (Letch worth, 

 Herts : W^m. J. Brooks and Co.) Prices 45. 6d. and 

 55. 6d. 

 This very useful adjunct to the ordinary- T-square 

 is one of the best of the devices which have recently 

 been introduced to facilitate the work of the draughts- 

 man, and it will be much appreciated by all who are 

 engaged in mechanical and architectural drawing. 

 The contrivance is simple in character, moderate in 

 price, and well made, and is designed so as to be 

 readily attachable to any existing square, no altera- 

 tion of the drawing board being required. By its use 

 the T-square, without loss of freedom, is instantly 

 locked in any desired position on the board, thus 

 freeing both the hands of the operator. The lock 

 may be put out of action at will, and the T-square 

 manipulated in the ordinary manner. The " lock " 

 attachment will be found extremely serviceable when 

 used with a board which rests horizontally, as on a 

 table, but when the board is much inclined or is 

 vertical, the employment of this or a similar device is 

 indispensable. There are many teachers who might 

 with great advantage utilise this apparatus for black 

 board work. 



