FrBRuary 4, 1904] 
NATURE 31 
NI 
state of process work will be astonished at the wealth 
and efficiency of methods that are at his service as 
shown by the admirable specimens which are included 
in this volume. : 
The present issue is considerably larger than its 
predecessors, both the articles and illustrations being 
more numerous; greater prominence is given also to 
the work of various technical schools and institutions. 
Enough, perhaps, has been said to indicate the value 
of this book, which so beautifully portrays the present 
stage of advancement in process work. 
Geometrie der Dynamen. By E. Study. Two vols. 
Pp. xiii+603. (Leipzig: B. G. Teubner, 1gor and 
1903.) ; 
Tue title of this book is somewhat misleading. The 
object of the first two parts is the discussion of certain 
geometrical theorems. From these the laws for the 
composition of wrenches (Dynamen) can be deduced 
as particular cases. To this special application, from 
which the book: takes its title, only pp. 116 to 121 are 
devoted. In the first part of the book the geometrical 
theorems (which deal chiefly with the composition of 
vectors, wedges, motors, &c.) are proved by purely 
geometrical methods, and the reader is assumed to 
have only a good working acquaintance with pure 
geometry, and in particular a knowledge of the theory 
of the composition of screws and translations (such as 
is supplied, for instance, in Schoenflies’s ** Krystall- 
systeme und Krystallstructur,’’ pp. 326 to 340). In 
the second part the analytical proofs of the same geo- 
metrical theorems are given, but the author still con- 
fines himself to elementary methods. The third part, 
which contains the larger portion of the book, appeals 
to a more advanced class of readers who are familiar 
with the method of modern analysis and the theory 
of groups. Here the author seeks to supplement the 
worl: of Plucker, Ball, and Sturm, and to give a com- 
plete discussion and classification of linear line-com- 
plexes. A good index and table of contents are given 
in the second volume. lala dale 
The Schoolmaster’s Yearbook and Directory, 
Pp. Ix+1030. (London: Swan Sonnenschein 
Cor. Ltd’; 1904.) Price 5s. net: 
1904. 
and 
Tunis is the second annual issue of a very useful publi- 
cation. It is, what on the title-page it professes to 
be, a reference book of secondary education in 
England and Wales. The book consists of two parts; 
the first contains general information and the second 
comprises lists of secondary schools for boys and of 
the masters who teach in them. The general inform- 
ation would have been more useful and more easily 
accessible had it been considerably condensed; for the 
essential matter in works of reference is to have the 
important facts clearly presented with a minimum of 
description. The ‘‘ Yearbook ’’ is, however, sure to 
be widely used, and deserves the popularity it has 
secured, 
Junior Country Reader. J. True Animal Stories. 
By SESE ave BuchananwibeAu. and R. R. C. 
Gregory. Pp. vi+121. (London: Macmillan and 
Co., Ltd., 1903.) Price ts. 
TnEsE tales, told in very simple language, are sure to 
please children of seven or eight years of age. The 
stories are founded on fact—some of them upon 
observations recorded from time to time in Nature. 
The illustrations, from photographs by Mr. Charles 
Reid, are numerous and good. The book should serve 
ore to awaken in children an interest in animal 
11é. 
NO. 1788, VOL. 69] 
LETTERS TO THE EDITOR. 
[The Editor does not hold himself responsible for opinions 
expressed by his correspondents. Neither can he undertake 
to return, or to correspond with the writers of, rejected 
manuscripts intended for this or any other part of NaTuRE. 
No notice is taken of anonymous communications. ] 
Destructive Action of Radium. 
It may interest some to know that radium destroys vege- 
table matter. I Happened to replace the usual mica plates, 
used to keep in the small quantity of radium in its ebonite 
box, with a piece of cambric, so as to permit the whole of 
the emanations to pass out, mica stopping the a rays. 
In four days the cambric was rotted away. I 
placed it now several times with the same result. 
BLYTHSWOOb. 
Blythswood, Renfrew, N.B., February 1. 
have re- 
Phosphorescence of Photographic Plates. 
Witt reference to letters in Nature of January 28 and 
preceding numbers, on ‘**‘ Phosphorescence of Photographic 
Plates,’’ it seems to be not out of place to direct the atten- 
tion of those interested in the subject to IMzedemann’s 
Annalen of 1888, vol. xxxiv. There will be found, on pp. 
918-925, information which may prove of use in further 
investigation. P. LeENarD. 
Kiel, January 3r. 
The French Academy. 
Wuat Mr. J. Y. Buchanan says (p. 293) about the French 
Academy is to me much more wonderful than the revela- 
tions of radium. It appears that there is a happy land close 
by where a scientific man of recognised standing can indulge 
in the luxury of original research, and then send in an 
account of his work, not to have it rejected by the opinion 
of, say, a couple of fellow-men, but actually to have it 
published as a right! This seems impossible. It the 
encouragement of original research. Perhaps it is hopeless 
to expect such freedom in this stick-in-the-mud country, 
which is so much in love with tradition and antiquated 
forms. Without any desire to be ‘‘ contumelious,’’ I would 
say that our Royal Society reminds me of the House of 
Lords in many respects. OLIveR HEAVISIDE. 
January 31. 
is 
Ambidexterity. 
Ix certain schools, notably, for instance, in Mr. Liberty 
Tadd’s art schools in Philadelphia, children are taught to 
become ambidextrous, at least to a considerable extent. 
The advantages of this plan have seemed to be evident, but 
Mr. Wm. Hawley Smith, the well-known writer on 
educational topics, has lately (School and Home Education, 
March and October, 1903) argued against it. In a letter 
just received from him, his views are concisely summed up 
as follows :—‘‘My notion is, that it is not worth while to try 
to make all our children ambidextrous. I believe that it is 
far wiser to follow nature’s lead, with each individual child, 
and develop them in the use of their hands as they naturally 
wish to use them. I am sure that, in most cases, we 
shall fail to secure real skill with either hand if we strive 
to train both to do the same work.’’ Mr. Smith further 
argues that it is hard enough to train one hand to do the 
more complicated kinds of work, and that it does not pay 
to waste energy trying to accomplish the more difficult feat 
of training both. Of course the validity of this argument 
depends largely upon the assumption that the lack of 
coordination ordinarily seen in adults is inherent, and not 
the result of acquired habit, or not largely so. It is perhaps 
allowable to suggest that this point has not yet been fully 
decided. It is also a question whether the relative inability 
of one hand is correlated with an-inefficiency of the opposite 
side of the brain, or putting it another way, whether the 
extra muscular activity necessary to train two hands instead 
of one involves a similar increase in mental activity. 
There is, however, a third possible plan to follow. While 
I am in nearly all respects right-handed, I draw with my 
