NEBULAR THEORY. 363 
sult which was not founded upon calculation and obser- 
vation.* Perhaps it is to be regretted that they did not 
receive a more complete development, especially in so far 
as concerns the division of the matter into distinct rings ; 
perhaps it would have been desirable if the illustrious 
author had expressed himself more fully respecting the 
primitive physical condition, the molecular condition of 
the nebula at the expense of which the sun, planets, and 
satellites, of our system were formed. It is perhaps 
especially to be regretted that Laplace should have only 
briefly alluded to what he considered the obvious possi- 
bility of movements of revolution having their origin in 
the action of simple attractive forces, and to other ques- 
tions of a similar nature. 
Notwithstanding these defects, the ideas of the author 
of the Mécanique Céleste are still the only speculations of 
the kind which, by their magnitude, their coherence, and 
their mathematical character, may be justly considered as 
forming a physical cosmogony ; those alone which in the 
present day derive a powerful support from the results 
of the recent researches of astronomers on the nebule of 
every form and magnitude, which are scattered through- 
out the celestial vault. 
In this analysis, we have deemed it right to concentrate 
all our attention upon the Mécanique Céleste. The Sys- 
téme du Monde and the Théorie Analytique des Probabil- 
ités would also require detailed notices. 
The Exposition du Systéme du Monde is the Mécanique 
Céleste divested of the great apparatus of analytical for- 
mule which ought to be attentively perused by every 
astronomer who, to use an expression of Plato, is desir- 
* Laplace has explained this theory in his Exposition du Systeme du 
Monde (liv. iv. note vii.).— Translator. 
