iA” eae 
Meéechanique Célesie. 378 
that the several varieties of prehnite dif«r in their chemical 
composition much less than has been generally supposed, 
Another candidate for the ame degree, Mr. P. N. Sevén, 
has examined a specimen of Olivine Gans mount Somme, 
near Naples he composition of this substance, as deter- 
mined by Klaproth, woud seem hardly to admit of its baits 
associated with chrys 
Th HON are the results of t two analyses made by 
M. Sevé 
- 40.08 Oxyg. 20.16 40.16 Oxyg. 20.20 
pre 7 perks it eae ¢* jp  baaet 
um, 15.26 A Sat Ae » 350 
“Manganos.. 0.48 0.10 
my -* 0.18 0.10 
maaaianerd ———— 
100.24 100.61 
results, so widely different from those of Klaproth’s 
analysis, clearly jestify the association of Olivine in the same 
; Cc. 
species with chrysolite. H. 
14. Mechanique Céleste.—The fifth and last volume of this 
great work of M. de Laplace has made its appearance, in- 
which the question of the form of the earth is discussed in 
various new pointsof view: viz. Ist. Thedynamic effect ofthe 
presence and distribution of the waters on the surface of the 
globe. 2dly. Th 
jected. 3dly. The change of size which may result from the pro- 
gressive cooling of the earth. The author has arrived atthefol- 
lowing results: That thegreatmassof the earth isby 00 means 
homogeneous; that the beds situate at the greatest depth are 
the most dense; that those beds are disposed regularly round 
the centre of gravity of the ap and that their form differs 
little from that of a curve surface, generated by the revolution 
of an ellipsis; that the density o of water is nearly five times 
less than the mean density of the earth; that the presence 
and distribution of the waters on the surface of the earth do 
not occasion any considerable alterations in the law of the di- 
minution of the degrees, and in that of weight ; that the theory 
sider isplacing of the poles at the surface of 
the ciith JF takiniscible, and that every geological system 
founded on such an hypothesis, will not at all decord with 
the existing knowledge of the causes. which determine the 
form of the earth; that the temperature of the globe has not 
a 
=O 
“sensibly diminished since the days of Hipparchus, Johove 
