NATURE 



[November 14, 1912 



there is no part of the anatomy of the engine which 

 has not a place in the work. Metric measures have 

 been converted by the translator, but the tabulated 

 dimensions of Continental engines have been re- 

 tained in millimetres in parallel columns. 



(5) The cost of mixing and laying concrete is 

 essentially governed by local circumstances, and it 

 would be unsafe to generalise from isolated results, 

 however carefully they may have been collected. 

 The authors have been at great pains to collect 

 information based upon work done in the United 

 States, and no doubt with due alloviance for the 

 difference in the cost of labour and materials and 

 the varying rate of output of work, much of their 

 conclusions would be applicable to other conditions 

 and places. But the work is not wholly confined 

 to questions of cost, for it contains much valuable, 

 if incidental, information concerning the making 

 of concrete in bulk, form of moulds, reinforcement 

 for ferro-concrete and other matters pertaining to 

 construction in this material. It is to be regretted 

 that so much prominence was given to costs, 

 though the title of the work very clearly points 

 to this as the dominant feature. Nevertheless, 

 with due allowances, as a reference book there is 

 much in it for the architect and engineer, and it 

 is eminently satisfying to know that the figures 

 were obtained by close application and systematic 

 study of construction work for many years. 



OUR BOOKSHELF. 



Manual Training I-I'oodit'orfe Exercises Treated 

 MathematicaUy. A Scheme for Linking up 

 Practical Mathematics with Woodwork"; in- 

 cluding a Complete Course of Mensuration. 

 By F. E. Drury. Pp. xi-i-215. (London: G. 

 Bell and Sons, Ltd., 1912.) Price 2s. 6d. 

 As is indicated by the title, the author's object in 

 preparing this volume has been to show how- 

 practical mathematics may be linked up with 

 woodwork in the form of mensuration, S.c. The 

 liook is intended for use in preparatory day trade 

 schools, some secondary schools, and in evening 

 continuation and technical courses of an elemen- 

 tary character. It is stated that the work of 

 calculation is intended to be an application of the 

 principles received in lecture and experimental 

 classes, but it will lie seen that these may, in a 

 large measure, be imparted by the woodwork 

 teacher if he has a generous allowance of time. 

 With this end in view, the book contains a very 

 good systematic course in mensuration, elementary 

 algebra, and the construction and properties of 

 simple graphs; the application of these principles 

 to the course of woodwork exercises provided is 

 clear and good, and the book should be very 

 useful to manual instructors who are expected 

 to train boys both in practical mathematics and 

 woodwork. 



As to the desirability of adopting this course 

 NO. 2246, VOL. 90] 



there may be difference of opinion, especially with 

 reference to evening schools, where the time per- 

 mitted for actual work in the wood shop is very 

 limited. Any reason which may be advanced for 

 bracketing together woodwork and mathematics 

 may equally well be applied to other branches of 

 practice, with a consequent multiplication of the 

 number of classes m practical mathematics carried 

 on in the same building, each no doubt selecting 

 those portions which appear to suit the particular 

 trade invohed. It is fairly obvious that such a 

 plan — already adopted in some institutions — 

 cannot fail ultimately to lower mathematical 

 standards. The author has been successful in 

 carrying out his views in the book, and, if it be 

 regarded as a further means of interesting students 

 in the woodwork shop in their work in classes 

 under the supervision of mathematical teachers, 

 it can be highly commended. The woodwork 

 examples are good, and the book is well and 

 clearly illustrated. 



Compendia Elemental de Zoologia. By Angel 

 Gallardo. Pp. 360. (Buenos Aires : Angel 

 Estrada y Cia, 19 12.) 

 Prof. Angel Gallardo has prepared a useful 

 elementary text-book of zoology, specially adapted 

 for the Argentine Republic. After an introduction 

 contrasting organisms and inorganic things, com- 

 paring plants and animals, describing cells and 

 tissues, and the early stages of development, dis- 

 cussing the factors of evolution and other gener- 

 alities, the author passes to a rapid survey of the 

 animal kingdom. The book is very clearly and 

 tersely written, with numerous illustrations, for 

 the most part admirable. In the classification 

 adopted, "Tipo vii., Lofostomas," includes the 

 three classes — Rotifers, Bryozoa, and Brachio- 

 pods — characterised by the tentacular apparatus 

 at the mouth. Still more doubtful is "Tipo viii., 

 Gusanos," which includes Annelids and Plathel- 

 minthes, characterised by having trochosphere 

 larvae. 



Twelve Moons. By Frances A. Bardswell. Pp. 



90. (London : Elkin Mathews, 1912.) Price 



25. 6d. net. 

 In twelve short sections devoted to the respective 

 months of the year, the author expresses pretty 

 sentiments upon the changing beauties of the 

 countryside. She loves the poetry of nature ; and 

 her words will awaken sympathetic response in 

 readers who are content to contemplate the surface 

 of things. The old proverb " February Fill-dyke " 

 leads her to say : "To brim the ponds and flood 

 the waterways is the mission of the month." As 

 a matter of fact, the average rainfall of February 

 in England as a whole is less than that of either 

 January, August, October, November or Decem- 

 ber, though there are local differences. Possibly the 

 explanation of the proverb is not that "deluges of 

 rain " actually fall in February, but that the water- 

 courses begin to fill up during that month as the 

 result of the rise of the water-table due to the 

 rainfall of preceding months. 



