266 
drawn from Prof. Kapp’s large practical experi- 
ence in electrical engineering. The printing and 
get-up of the book are all that could be desired. 
(2) Dr. Alexander Russell’s book is of a more 
theoretical and mathematical character, and is the 
second edition of the second volume of a treatise 
on the theory of alternating currents. It appeals 
therefore to an advanced student or designer who 
is not averse to full mathematical treatment. A 
valuable feature of the book is the list of refer- 
ences to other works and papers given at the end 
of each chapter. The book consists of twenty 
chapters, covering the full theory of alternators, 
transformers, induction motors, commutator 
motors, rotary converters, and electric power 
transmission by alternating currents. Chap. iii. 
comprises a very complete discussion of Fourier’s 
theorem and the practical methods of determin- 
ing the constants in the Fourier expansion. 
Although chiefly of interest to the pure mathe- 
matician, the electrical engineer has frequently 
occasion to enter this field of analysis. Neverthe- 
less, if much of it has to be done, as in the analysis 
of tidal curves, then some mechanical means, such 
as Lord Kelvin’s harmonic analyser, would be 
used. 
A’ very important application of pure mathe- 
matics is dealt with in chap. xix., viz. the 
discussion of the properties of hyperbolic func- 
tions and their application in the problem of the 
long-distance alternating-current' power trans- 
mission. No electrical engineer concerned with 
this subject can afford to be ignorant of these 
modern methods. 
Chap. xiv gives a good account of the 
general theory of induction motors, and chap. 
xvi of the commutator motor. In this con- 
nection we confess we should like to have seen 
included the theory of Goldschmidt’s frequency- 
raising alternator, now of importance in wireless 
telegraphy. It has been treated by Pupin as a 
particular case of asymmetrical rotors in unidirec- 
tional magnetic fields. Also another subject of 
interest in close connection is the use of pairs of 
static transformers for raising frequency by means 
of unsymmetrical flux in the cores. The question 
of the efficiency of this method of frequency rais- 
ing needs discussion. 
It would have been an advantage to in- 
clude some general description of extra high 
frequency alternators, such as those of Alexander- 
son and the method of frequency raising by. 
alternators in cascade suggested by MM. Latour 
and Béthenod. Nevertheless, the book as it is is 
a work.of the greatest value to all concerned with 
alternating-current working, and no advanced 
student should neglect it. 
(3) a he third book on our list is of a less 
ambitious type, but is intended to provide within 
very moderate compass for the needs of students 
in universities and technical colleges whose 
mathematical knowledge is of restricted range. 
To each chapter is appended a seriés of examina- 
tion questions and numerical examples, with the 
answers in many cases added. The diagrams and 
Wo. 2458, vor. 98] 
NATURE 
[DECEMBER 7, 1916. 
illustrations are in most cases new and well — 
selected. 3 | 
The chapter on switchgear and protective appli- 
ances for high-tension transmission is a particu- 
larly useful one, and the diagrams are extremely — 
instructive. The plates at the end showing the- 
modern types of switchgear and panels for 
handling large currents are valuable. 
The book strikes us as very well adapted for 
second-year students in the electrical engineering’ 
departments of our colleges, and as a text-book, 
from its moderate size and yet thoroughly practical — 
character, it will be popular. It is one of the ex-_ 
cellent books in the Cambridge Technical Series’ 
edited by Mr. P. Abbott, and the fact that it is 
printed at the Cambridge University Press is a 
sufficient assurance that its typography and illus- 
trations are of the very best. ; 
J. A. FLemInc. 
THE INFLUENCE OF INTERNAL SECRE- 
TIONS ON SEX CHARACTERISTICS. — 
The Sex Complex: A Study of the Relationships - 
of the Internal Secretions to the Female Char- 
acteristics and Functions in Health and Disease, - 
By Dr. W. B. Bell. Pp. xvii+233- (London: 
Bailliére, Tindall) and Cox, 1916.) Price — 
12s. 6d. net. 
R. BLAIR BELLI, belongs to that limited 
group of medical men who resort to the 
experimental laboratory to extend and verify their 
means of diagnosis and treatment of clinical con-— 
ditions. He has given us, under the title ‘The Sex — 
Complex,” observations made in the course of a 
prolonged inquiry into the nature of the secondary 
sexual characters of the human body—more par- 
ticularly the normal and abnormal manifestations. — 
of sex in woman. His work will appeal to all 
who are trying to unravel the obscure and delicate 
manner in which the sexual system is developed 
and balanced. From prehistoric times mankind 
has been familiar with the effects of castration; 
the effects which followed that operation gave rise 
to the belief that the sexual characteristics of the — 
male, both mental and bodily, were determined by~ 
the testes, while, conversely, feminine characters. 
depended on the ovaries. ‘ ’ 
The chief aim which Dr, Blair Bell has in view 
in his present work is to prove that sexual char- 
acterisation is the manifestation of a complex 
glandular system of which the sex-glands form’ 
only a part—a system which includes all the glands 
of internal secretion—the pituitary, the pineal, the. 
thyroid and parathyroids—the thymus, and supra- 
renal bodies. The normal development of male 
and female characters depends on the interaction 
and co-operation of all the members of this com~ 
plex glandular system; it is in a disturbance of - 
the balance of the various members of the glan- 
dular system that Dr. Blair Bell seeks for a 
rational explanation of the sexual disorders to 
which so many modern women are liable. Beyond 
doubt the method of investigation which the 
author has adopted is one which promises a 
