612 
of the earth, in short, into his infra-granite 
zone. He holds that the water which comes 
out in volcanoes cannot be original, because the 
temperature of the globe is constantly decreas- 
ing and that past conditions were still less favor- 
able than the present ones for the maintenance 
of water in the interior. He thinks, therefore, 
that the water is of recent introduction. 
“The solution of the question,’’ states our 
author, ‘‘appears to result from some very sim- 
ple experiments of M. Stanislas Meunier.’’ 
Without describing the experiment which in no 
way duplicates the condition of the earth’s crust 
at a depth, the author supposes that the water 
is brought into the infra-granitic zone as water 
of consolidation and crystallization embodied in 
fragments of rock which fall down along fault- 
planes and zones of crushing. The ‘ falling’ of 
these hydrated rocks into the heated regions of 
the globe is supposed to give rise to volcanic 
explosions and as is stated in the next chapter 
to earthquakes also. The author very frankly 
states that he is obliged to note the profound 
astonishment which the first publication of his 
views elicited. 
In the experiments on folds some interesting 
points are dwelt upon concerning the intersec- 
tion of planes of fracture which arise, but these 
artificial faults are not compared with those of 
any particular region. Under the head of schis- 
tosity are described experiments which appear 
in reality to have induced a kind of cleavage as 
that term is understood in English. Fractures 
are produced by compression in some experi- 
ments which lead the author to reject Daubrée’s 
famous radiating fractures produced by torsion, 
seemingly on the ground that such fractures 
have ‘not anywhere been observed.’ 
The general distribution of mountains upon 
the globe last of all comes in for experimenta- 
tion in the clever methods of the author. A 
small hemispherical shell has stretched over it 
a rubber layer coated with plaster, in such a 
manner that when the foundation, which rep- 
resents the contracting nucleus of the globe, is 
allowed to retreat, the contraction of the rub- 
ber layer induces compression of the plaster. 
This stress is relieved by circumpolar lines of 
shearing and displacement, the overthrust being 
poleward in direction. The author points out 
SCIENCE. 
[N. S. Von. X. No. 252. 
the analogies which seem to exist between this 
model and the arrangement and orogenic move- 
ments of the mountain systems of Europe. 
The researches of Suess on the northwesterly 
movement of the Eurasian thrusts should be 
noted as favoring this hypothesis, but it is diffi- 
cult to see in what way the view is exemplified 
on the North American continent. 
The book is closed with a ‘ Postface’ or state- 
ment, with which most geologists will probably 
agree, that this volume sets forth facts amply 
sufficing to justify the raison d’étre of experi- 
mental geology. Whatever misgivings one may 
entertain concerning the decisive character of 
some of the experiments, there can be no doubt 
of the suggestiveness of the original and ingeni- 
ous methods which the author has brought to 
bear upon some of the largest questions of dy- 
namical geology. The book is illustrated with 
a few good cuts and is well printed. A list of 
contents takes the place of a good index. The 
publishers have taken the liberty of appending 
35 pages of advertising matter which might 
have been omitted. 
J. B. W. 
Legons sur la détermination des orbites professées 
ala Faculté des Sciences de Paris. Par F. T1s- 
SERAND; redigées et développées pour les 
ealculs numériques par J. PERCHOT; avec 
une préface de H. PoIncARE. Paris, Gau- 
thier-Villars. 1899. 4to. Pp. xiv + 124. 
These lectures formed a part of the course in 
mathematical astronomy delivered at the Sor- 
bonne by the late Professor Tisserand, but the 
important question of the determination of 
cometary and planetary orbits was not treated — 
in his well-known treatise on celestial me- 
chanics. The only work in the French language 
devoted to the numerical elements of orbits is 
the translation of Oppolzer’s treatise, which is 
a most useful book to the computer, but neither 
easy nor attractive to the reader; on the con- 
trary the lectures of Tisserand exhibit the 
clearness of exposition and the simplicity and 
elegance of method which uniformly character- 
ize his writings, so that all devotees of mathe- 
matical science will be indebted to M. Perchot 
for this edition of the unedited lectures of his 
lamented master. Professor Poincaré’s pre- 
