APRIL 4, 1907 | 
NATURE 531 
its units are no longer subject to experiment? Most 
assuredly not.”’ 
Our author undertakes the herculean task, we 
venture to think successfully, of setting the study 
of phylogeny on a surer foundation. The reason that 
phylogenetic inquiry has become discredited is that 
the majority of biologists are neither so stupid that 
they are content to dabble with phylogeny nor clever 
enough to make it a great and fruitful sphere of 
inquiry—a field fit for the exercise of the highest 
intelligence. ; 
The experimental method has its limitations no less 
than its fascination. It is not merely a paradox to 
say that in biology those things with which we can 
experiment most are those which to the organism 
matter least. The reason is that we are not the first 
to start experimenting. Nature has been there before. 
For example, the range of continuous variation in an 
organism may either be the direct result of the con- 
stitution of the living substance or it may have been 
determined by the most stringent selection acting 
since life dawned. If, therefore, we institute experi- 
ments on variation—for example, the determination of 
the effect of heat on the range of variation—we may 
either be studying one of the simple properties of 
protoplasm or discovering the limits within which 
natural selection allows the particular organism dealt 
with to vary under the conditions of heat, e.g., to 
which we subject it. The really fundamental pro- 
cesses do not lend themselves to experiment. That is 
how they have become fundamental. Everyone who 
wishes to train himself to study them should read 
Prof. Montgomery’s book. 
There are a few trifling misprints, e.g. ‘‘ embryon- 
ing”? in the table of contents; and Mendel worked, 
not with the sweet, but with the culinary pea. 
i\ IDE DY 
ELECTRIC RAILWAYS. 
Electric Railway Engineering. By H. F. Parshall 
and H. M. Hobart. Pp. xxiv+475. (London: 
Archibald Constable and Co., Ltd., 1907.) Price 
42s. net. 
HE authors of this work have already introduced 
a series of technical works upon dynamo design 
and kindred subjects, and Mr. Hobart is also known 
as the author of a recent work upon the steam 
turbine. 
In the present volume the authors deal with a 
wider range of subjects, and, in short, treat of the 
whole question of heavy ‘electric traction,’’ that is, 
traction as applied to railways rather than to street 
tramways. Such a book was required, and will be 
welcomed by the growing class of engineers who 
wish to add to their experience of steam railway work 
some knowledge of electrical engineering, which is 
more and more coming to invade the field of traction. 
Technical works of this kind may, as a rule, be 
divided into two classes; on the one hand are the 
highly technical works which deal with the more 
scientific aspects of the subject, and of which the 
NO. 1953, VOL. 75 | 
authors’ ‘‘Dynamo Design’’ is an example; on 
the other are the entirely practical works which, at 
their worst, degenerate into collections of specifica- 
tions. The present volume endeavours, not unsuccess- 
fully, to combine these two, and to give the reader a 
clear knowledge of the fundamental principles that 
underlie the application of electricity to haulage, 
illustrations of the methods employed in carrying this 
into effect, and actual examples and details of con- 
struction. What it does not fully supply, and what, 
unfortunately, books of this kind very seldom contain, 
are the commercial results obtained from the adoption 
of electric traction. It may be said that this is out- 
side the scope of an engineering treatise; and if the 
work is to comprise engineering in the sense in which 
that word was commonly used during the last century 
the answer is justified, for the engineer of those days 
was concerned with the question of ‘‘ will it work? ”’ 
rather than the question of “‘ will it pay?’’ But the 
engineer of the twentieth century has become more 
and more obliged to look upon the latter as the test 
of successful engineering, and until a book can be 
produced dealing with electric traction from the 
operating point of view such works will not, it is to 
be feared, have much effect in influencing railway 
authorities to replace steam haulage by electric trac- 
tion. Apart from these limitations, however, the pre- 
sent volume is most valuable, for although a 
considerable portion of the matter has been already 
published in one form or another, there was a great 
need for bringing together all that has been done 
and written. 
The choice of the system to be adopted upon any 
particular part of a railway, although necessarily in- 
fluenced by first cost, should ultimately be dependent 
upon its suitability for use upon the railway as a 
whole, and the results obtained from electrification 
must be judged in reference to the whole railway 
undertaking rather than in connection with one sec- 
tion. In connection with the vexed question of the 
relative advantages of direct current, single phase 
or three phase, the authors do not undertake to pre- 
dict the form that the ultimate electric railway in- 
stallation will assume, contenting themselves with 
pointing out the merits of each, and emphasising the 
fact that standardisation has been one of the great 
elements of success in steam railway working, and 
that the adoption of electric traction upon railways 
in the future will be slow until standardisation is 
adopted. 
Coming now to the contents of the book itself, 
it consists of three parts, dealing respectively with 
the mechanics of electric traction, the generation and 
transmission of the electrical energy, and the rolling 
stock. Chapter i. deals with ‘“‘ tractive resistance at 
constant speed,’’? and gives the results of applying 
both theoretical and arbitrary formule to the result 
obtained in actual practice. 
Chapter ii. deals in a similar manner with the 
problem of acceleration. Many useful curves of 
acceleration, speed-time, and speed-distance are given. 
Chapter iii. deals with tractive force in relation to 
acceleration, while chapter iv. deals with the 
