NEBULAR THEORY. 363 



suit 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 Mecanique Celeste 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 nebulae 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 Mecanique Celeste. The Sys- 

 teme du Monde and the Theorie Analytique des Probabil- 

 ites would also require detailed notices. 



The Exposition du Systeme du Monde is the Mecanique 

 Celeste divested of the great apparatus of analytical for- 

 mulae 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. 



