Wea TORE 
THURSDAY, OCTOBER 23, 1902. 
THE ENCYCLOPEDIA BRITANNICA. 
The Encyclopaedia Britannica, vols. xxviii. and xxix. 
Being the Fourth and Fifth of the New Volumes. 
Ele-Gla. Pp. xix + 742. Gla-Jut. Pp. xx + 763. 
(London: A. and C. Black, and the Z7mes, 1902.) 
HE prefatory essay to vol. xxvili. is by Sir Leslie 
Stephen upon the subject of “The Growth of 
Toleration.” It is pointed out that one dominant factor 
in the development which has taken place has been the 
growth of the natural sciences ; and reference is made to 
the influence exerted by scientific investigation upon 
traditional beliefs and dogmas. Mr. Benjamin Kidd 
contributes to vol. xxix.a prefatory essay on ‘* The Appli- 
cation of the Doctrine of Evolution to Sociological 
Theory and Problems.” 
There are many scientific articles in the two volumes, 
several being of great importance. Among the articles 
to which attention must be directed are the following :— 
Vol. xxviii. : Electricity and electricity supply, by Prof. J.A. 
Fleming, Mr. W. C. D. Whetham, Prof. J. J. Thomson, Dr. 
L. Duncan and Mr. E. Garcke ; electrochemistry, Mr. 
W. G. McMillan ; electromagnets, Prof. J. A. Fleming ; 
embryology, Mr. Adam Sedgwick and Dr. A. E. 
Driesch ; energetics, Dr. J. Larmor ; engines, Prof. J. A. 
Ewing; England and Wales (geography), Dr. H. R. 
Mill ; Entomostraca, Rev. T. R. R. Stebbing ; evolution, 
Dr. Chalmers Mitchell; fisheries, Mr. W. Garstang ; 
forests and forestry, Prof. W. Schlich and Mr. G. 
Pinchot (United States); Fourier’s series, Dr. E. W. 
Hobson ; analytic functions, Mr. H. F. Baker ; functions 
of real variables, Prof. A. E. H. Love; fungi, Prof. 
Marshall Ward ; fusion, Prof. H. L. Callendar; gas and 
gas lighting, Prof. V. B. Lewes; gaseous fuel, Prof. G. 
Lunge ; artificial gems, Sir William Crookes; geography, 
Dr. H. R. Mill; geology, Sir Archibald Geikie ; geo- 
metrical continuity, Rev. Charles Taylor ; line geometry, 
Mr. J. H. Grace, and non-Euclidean geometry, the Hon. 
A, A. W. Russell. Vol. xxix. : Theory of groups, Prof. 
W. Burnside; gunnery, and gyroscope, Prof. A. G. 
Greenhill; gymnosperms, Mr. A. C. Seward ; halos, the 
late Prof. P. G. Tait ; Helmholtz, Prof. J.G. McKendrick; | 
hemichorda, and hydrozoa, Dr. G. H. Fowler; heredity, | 
| development of the theory of the representation of 
and hybridism, Dr. P. Chalmers Mitchell ; Huxley, Sir 
W. T. Thiselton-Dyer ; hygiene, Colonel J. Lane Notter ; 
ichthyology, Dr. A. Giinther ; insects, Dr. D. Sharp ; iron 
and steel, Prof. H. M. Howe; irrigation, Sir Colin 
Campbell Scott- Moncrieff. 
It is impossible to describe the whole of these articles 
in a notice of limited length, but from this group of | 
scientific contributions to the “ Encyclopzedia ” we select 
a few for brief notice. 
So large a part, nearly one-sixth, of vol. xxviii. is | 
devoted to electrical subjects that we-cannot, with the | 
space at our disposal, do much more than enumerate the 
branches treated. Under the heading ‘“ Electricity,” 
Prof. Fleming writes on electric conduction, current and 
units ; Prof. J. J. Thomson on discharge through gases 
and electric waves ; and Mr. Whetham on electrolytic 
conduction. These articles cover the greater part of 
NO. 1721, VOL. 66] 
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electrical theory; the practical applications are dealt 
with in separate contributions. Mr. Whetham’s discus- 
sion of electrolytic conduction gives a full and favourable 
account of the dissociation theory ; the student has there- 
fore an opportunity, from this article and from that by 
Prof. Armstrong on “ Chemistry,” of considering both 
sides of the question. The electrochemist is indeed 
particularly well catered for in the new volumes, since, in 
addition to the articles already mentioned, Mr. McMillan 
contributes two articles to the present volume on 
“Electrochemistry” and “ Electrometallurgy.” These 
deal with the industrial applications, the first with re- 
fining of metals, electrotyping and plating, and alkali and 
chlorate manufacture ; and the second with furnace pro- 
cesses, such as the production of aluminium and calcium 
carbide. A contribution on ‘“‘ Electromagnet,” written by 
Prof. Fleming, discusses magnetic flux, permeability and 
hysteresis. A long article on ‘* Electricity Supply ” deals 
with the principle of lighting by arc and incandescent 
lamps, with electric traction, and with the commercial 
aspects of the industrial development of electricity. 
The treatment of electric traction is hardly adequate if 
this is all that is to be given in the “ Encyclopaedia” ; for 
one thing, the article is entirely without illustration, a 
great disadvantage to the general reader. It is also to 
be noticed that there is a certain amount of repetition 
which might have been avoided ; thus, the theory of the 
arc is discussed at some length by both Prof. Fleming 
and Prof. J. J. Thomson. 
“Energetics” is a name commonly associated with a 
philosophy which proposes to abolish Newton's laws of 
motion and to deduce all the equations of dynamics from 
the single equation of energy. Dr. Larmor’s article 
deals with a much more useful field of study, including 
Carnot’s principle, the general thermodynamical equa- 
tions, free and available energy, and Gibbs’s important 
work on the equilibrium of chemical systems. It forms an 
excellent introduction to the study of thermochemistry. 
Pure mathematics is well represented in the present 
volumes. In an articlé on the “ Error Law,” Mr. Edgworth 
gives an account of the various proofs of the common law 
of error and of Prof. Weldon’s experimental verification, 
corrections for cases in which the number of elements is 
finite, normal and abnormal correlation, and applications 
to various problems in statistics. In the account of 
Fourier’s series, Dr. Hobson divides the historical 
functions by trigonometric series into three periods, the 
first period opening with the work of D’Alembert, 
Bernouilli and others in connection with vibrations ot 
strings, the second with Fouriers memoir of 1807 on 
the ‘Theory of Heat,” and the modern period being 
inaugurated by Riemann’s memoir of 1867. The article 
on “Analytic Functions” contains a good general ac- 
count of Weierstrass’s methods ; that on “ Functions of 
Real Variables ” deals largely with the continuum of 
real numbers, the domain of a variable, the doctrine of 
continuity, and the questions of differentiability and 
integrability of functions. Under “ Line Geometry,” we 
have a discussion of the properties of linear and non- 
linear complexes, congruences and ruled surfaces. In 
the article on “ Non-Euclidean Geometry,” Mr. Russell 
traces the yenesis of this important branch of pure 
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