THE STORY OF NINETEENTH-CENTURY SCIENCE 



opment out of these masses of the sidereal bodies which 

 we see. Thus far the mind follows readily ; but now 

 come difficulties. How happens it, for example, that 



JAMES LOUIS LAGRANGE 



the cosmic mass from which was born our solar system 

 was divided into several planetary bodies instead of re- 

 maining a single mass? Were the planets struck off 

 from the sun by the chance impact of comets, as Buffon 



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