number of differing theories are passed in rapid 
review and briefly criticised. The conclusion that 
is reached may perhaps be fairly given by the 
following extracts :-— 
“La cosmogonie va-t-elle donc sortir de l’age 
des hypothéses et de l’imagination pour devenir 
une science expérimentale, ou tout au moins une 
science d’observation? . On attend sans doute 
de moi une conclusion, et c’est cela qui 
m’embarrasse. Plus on étudie cette question de 
Vorigine des astres, moins on est pressé de con- 
clure. Chacune des théories proposées_ est 
séduisante par certains cétés. Les unes donnent 
d’une facon trés satisfaisante l’explication d’un 
certain nombre de faits: les autres embrassent 
davantage, mais les explications perdent en 
précision ce qu’elles gagnent en étendue; ou bien, 
au contraire, elles nous donnent une précision trop 
grande, mais qui n’est qu’illusoire et qui sent le 
coup de pouce. ... Nous ne pouvons donc 
terminer que par un point d’interrogation.” 
With one reservation, namely, that he does not 
propose to extend the explanation to cover all the 
varying types of stellar systems, our author 
inclines to accept a modified form of the nebular 
hypothesis of Laplace. At a time when it is the 
fashion rather to decry Laplace and to look upon 
his views as exploded it is refreshing to find a 
writer of the calibre of M. Poincaré standing up 
in his defence :— 
“C’est Vhypothése de Laplace qui rend le 
mieux compte de bien des faits; c’est elle qui 
répond le mieux & la question que s’est posée son 
auteur. Pourquoi 1’ordre regne- -til dans le 
systéme solaire, si cet ordre n’est pas dt au 
hasard? ” 
It must be borne in mind, however, that this 
position is maintained partly by ignoring some of 
the most recent criticisms that have been levelled 
at the nebular hypothesis. Full weight is given to 
the valuable modifications introduced by Roche, 
but, en the other hand, there is no mention of 
the recent work of Moulton, or of other critics. 
This leads one directly to state the weakest feature 
of the book under review. French cosmogonical 
speculation is naturally very fully treated, but the 
work of the men of science of other countries is 
selected for discussion in a somewhat haphazard 
manner. It would seem that a hook here or a paper 
there has caught the eye of the author, and has 
been introduced into the work. But no attempt has 
been made to form a complete survey of recent 
work, and much valuable research has been 
omitted, especially in the discussion of stellar as 
opposed to solar theories. The spectroscopic 
evidence in the theories of stellar evolution is 
given neither fully nor critically. In fact, 
the preface, useful 
save in 
criticism, even constructive 
Supplement to ‘“* Nature,” 
ee 7 TOL 2. Vii 
Thus two theories, each claiming to explain mony 
celestial phenomena, may be given in succeeding 
chapters. The two theories deal with the same 
phenomena, but they are incompatible. Save in 
the passage already quoted above from the preface, 
there is little to show the author’s own attitude to 
the speculations under review. It is true that 
“il peut étre utile de les faire connaitre, parce qu’on 
pourra un jour y trouver a glaner d’intéressantes 
vérités.” But the hook would have served a more 
useful purpose if M. Poincaré could have indicated 
more clearly with regard to each hypothesis where 
in his opinion lies the grain of truth which is 
worthy of the gleaning. 
In the detailed treatment of individual theories 
the value of the book lies largely in the lucidity of 
the statements. The writer has evidently enjoyed 
the opportunities of entering into a mathematical 
discussion whenever they have presented them- 
selves. This is notably the case in the account of 
the theory of M. du Ligondeés, and of the contrast 
between it and the kinetic theory of gases. The 
presentation of the analysis of Sir George Darwin’s 
tidal theories should prove stimulating to all 
students of his writings. A full discussion is given 
of the views of Dr. Arrhenius, and on the whole 
M. Poincaré sums up against his conclusions on 
“la mort calorifique de 1’Univers.’’ The views 
of other writers (See, Bélot, Schuster, Lockyer) 
are given for the most part without much 
criticism, but they provide very interesting read- 
ing, as, indeed, does the whole book. It should 
be added that the work of editing the lectures 
has been done very satisfactorily by Dr. Vergne. 
TANNINS, DYES, AND COLOURS. 
Allen’s Conmmercial Organic Analysis. Edited by 
W. A. Davis and S. S! Sadtler. Vol. -v-: 
Tannins, Analysis of Leather, Dyes and Colour- 
ing Matters, Dyestuffs of Groups 6 to 12, 
Colouring Matters of Natural Origin, Analysis 
of Colouring Matters, Colouring Matters in 
Foods, Inks. By the Editors and the following 
Contributors: W. P. Dreaper, J. F. Hewitt, 
W. M. Gardner, A. F. Seeker, P. H. Walker, 
E. Feilmann. Fourth edition. Entirely re- 
written. Pp. ix+704. (London: J. and A. 
Churchill, 1911.) Price 21s. net. 
N the first division of this work Mr. W. P. 
Dreaper deals with the tannins. On the 
question of the constitution of these widespread, 
numerous, and commercially important bodies 
there has been much discusSion. The tannin of 
gall-nuts (tannic acid, gallotannic acid) was 
formerly regarded as a glucoside, and by some 
ag is Se lacking throughout the work. ] authorities is still so regarded, or at least a 
218, voL. 89] 
