3oS 



NA TURE 



[September 2, 1922 



discussing the best size of the town for good social life, 

 considers, among other matters, the bearing of the 

 number of the population upon the question of educa- 

 tional facilities and artistic development, such as music 

 and the drama. Mr. Reiss raises some interesting 

 points in connexion with land values and the possibility 

 of co-operation with local authorities in the matter of 

 rating and the development of municipal activities. 

 For 1 In use of those who wish to pursue the subject 

 further, a bibliography is appended. 



Land and Sea Spin/ Reckoner. Designed by ('apt. 

 W. X. McClean. (London: Constructed by C. T. 

 Cooper and Sons, Ltd.) 1/. 12s. 6d. 



This is an instrument of the slide-rule type, which has 

 of late years met with considerable favour among 

 navigators for dealing with that class of problem in 

 which an approximate solution is sufficient. By 

 means of the instrument it is possible to obtain (1) 

 speed, when distance and elapsed time are known ; 



(2) elapsed time, when speed and distance are known ; 



(3) distance, when elapsed time and speed are known. 

 The slide-rule consists of two scales, namely, (<7) a time 

 scale, styled the " Slider," and (b) a distance scale, and 

 by setting these in correct mutual relation any of the 

 above problems can be dealt with in one simple opera- 

 tion. Thus, if elapsed time is 8'" 40 s , while distance 

 steamed is 3-2 miles, all that is necessary is to bring the 

 graduations denoting these two values vertically 

 opposite to each other, when the required speed, in 

 this case 22-2 miles per hour, is read off on the distance 

 scale, opposite the division on the time scale marked 

 one hour. 



A modification of the instrument, known as the 

 " Air Speed Reckoner," has a specially adapted 

 distance scale to meet the case of high speeds in the 

 navigation of the air. 



The manipulation of the scales is simple, and easy to 

 grasp, and the invention seems well adapted to the 

 purpose of dispensing with troublesome arithmetical 

 calculations which the designer appears to have had in 

 view. 



Diet and Rate: Anthropological Essays. By F. P. 



Armitage. Pp. vi + 144. (London : Longmans, 



Green and Co., 1922.) 75. 6d. net. 

 Mr. Armitage discusses the relation of diet to stature, 

 pigmentation, and head form. In reference to stature, 

 after an analysis of the food values of staple articles 

 of food in different parts of the world, he suggests that 

 each is associated with a particular type of physique. 

 and shows that scarcity of food is a concomitant of 

 diminutive stature, and vice versa. In dealing with 

 pigmentation, he shows that pigmentation varies with 

 the amount of salt which enters directly or indirectly 

 into the diet, the greatest quantity being consumed 

 by the fairer races. The question of pigmentation is 

 obscure, and although it is generally regarded as due 

 to environment, it is not clear how variation has been 

 brought about. It is not impossible that the chemical 

 action set up by salt may be one of the factors involved. 

 In regard to head form, the author suggests that the 

 difference between long and broad heads may be due 

 to the difference of muscular effort requisite in masti- 

 cating soft and hard foods. The author does not appear 



NO. 2757, VOL. I 10] 



to be aware that a similar suggestion, both as to the 

 effect of muscular action and as to the character of 

 food, was put forward by Prof. Arthur Thomson some 

 years ago. 



Introduction a I'etude des fonctions elliptiqiies a 

 I'usage des etudiants des facultes des sciences. Par 

 Prof. P. Humbert. Pp. 38. (Paris : J. Hermann, 

 1922.) 3 francs.. 



Elliptic functions are " not studied by mathe- 

 matical students unless they are specialists in mathe- 

 matical analysis, yet a knowledge of the most important 

 elementary facts about these functions is essential for 

 advanced work in many branches of pure and applied 

 mathematics. Prof. Humbert's object is to supply 

 this information in a conveniently brief form. Starting 

 with the elementary theory of residues and contour 

 integrals, the author introduces the notion of periodic 

 functions defined by integrals : doubly periodic func- 

 tions then follow, leading to the p function and 

 some of its most useful properties. We then get the 

 f and u- functions, and finally modular functions are 

 touched upon. The book forms a clearly written 

 introduction which cannot but encourage the student 

 to seek for further and more detailed information in 

 standard treatises. S. B. 



On the Edge of the Primeval Forest: Experiences and 

 Observations of a Doctor in Equatorial Africa. By 

 Prof. A. Schweitzer. Translated by Ch. Th. Campion. 

 (London : A. and C. Black, Ltd., 1922.) 6s. net. 

 The author resigned his professorship in the Liniversity 

 of Strasbourg in order to qualify in medicine with the 

 view of working among the natives of the French Congo. 

 His work is an account of five years' experience at 

 Lambarene on the Ogowe River. Prof. Schweitzer is 

 evidently a close observer, and he succeeds in giving a 

 vivid picture of the monotony of life in the oppressive 

 luxuriance of the tropical forest. The considerable 

 attention devoted to medical and surgical matters does 

 not lighten the gloom. There are a few interesting 

 reflections on some urgent tropical problems, such as the 

 labour question and the relation between blacks and 

 whites, which, in view of the author's experience, might 

 with advantages have been expanded. The book is a 

 short one, but not without value as a contribution to the 

 study of the negro and his relations with the trader and 

 missionary. 



Evolution of the Essex Rivers and of the Lower Thames. 

 By Prof. J. W. Gregory. Pp. 68. (Colchester: 

 Benham and Co., Ltd., 1922.) 25. 6d. net. 



As this book's geological contents occupy not quite 

 sixty pages, and as " Bibliography and References " 

 occupy three pages, and refer to fifty-nine different 

 memoirs, or papers, on. various points in Essex geology, 

 it is obvious that no brief view of its conclusions is 

 possible here. The views expressed as to the " Evolu- 

 tion of the Essex Rivers " and " The Relations of 

 Essex and Midland River Systems," etc., are not 

 antagonistic to those of previous writers, but are mainly 

 occupied by matters more or less outside those treated 

 by Essex geologists of an earlier date. In short, it 

 is a brief work of much value to all students of Essex 

 geology. T. V. Holmes. 



