RESOLUTION OF NEBULJ2. 23 



attention of the reader is solicited while we briefly explain 

 its nature, and unfold a summary of the evidences on which 

 it is founded. 



The idea that nebulae, or loose masses of fiery vapor, which 

 seemed to be floating in the depths of immensity, might form 

 the materials out of which nature elaborated suns and planets, 

 was originally propounded as a conjecture, by Sir William 

 Herschel ; but it was subsequently brought into more definite 

 and tangible form by Laplace, Comte, Nichol, and others. 

 The theory supposes that loose masses of nebulous vapor, at 

 first without definite form or movement, gradually assumed, 

 by virtue of gravitation, a regular spheroidal and rotating form, 

 lightest at the circumference, and gradually increasing in den- 

 sity toward the center, at which point the greatest density is 

 attained. It supposes that such forms were the original forms 

 of suns that the substance of these, in this diffused state, 

 originally extended from their present condensed, solar spheres, 

 to the outermost limits of the planetary systems which now 

 revolve about them ; and that by the combined processes of 

 rotation and further condensation, successive and concentric 

 rings were formed on the outer limits of the nebulous disks, 

 of which we have a faint illustration in the rings of Saturn. 

 These rings, it is thought, subsequently became broken up, 

 when the matter composing them naturally agglomerated into 

 spheres, which, by an analogous process of condensation and 

 evolution of rings, produced planets and their satellites. 



It is but just to remark that many of the supposed nebula, 

 which Herschel thought might form the materials of future 

 suns and systems, have subsequently, by the application of 

 powerful telescopes, and especially that of Lord Ross, been 

 resolved into stars, apparently so close together as to cause 

 the general hazy appearance which they present when viewed 



