CERTAIN HARMONIES OF THE SOLAR SYSTEM. 93 



by Sir John Herschel \_Outlines of Astronomy (872)] as quite supposable as conse- 

 quences of the clustering power, will be the more frequently avoided; and stars, 

 which, like our sun, may have planets in their keeping, will bear their attendants 

 away beyond the reach of harm. 



In view, then, of even the little that has yet been ascertained, may we not in 

 all humility ask whether this was not indeed the loay in whicli the Supreme Dis- 

 poser of both great and small events executed his vast purposes; the changes 

 being, alternately, destructive and conservative. 



For the growing leaf is fed by the exhalations which it finds in the atmosphere ; 

 and the leaf, in its decay, nourishes the vegetating tree ; the roots of that tree are 

 embedded in the debris of a comparatively ancient earth ; the earth itself, in view 

 of the nebular hypothesis (of Laplace), has been detached from the sun; and the 

 sun and other stars would now seem to be but the comparatively small fragments 

 or drops of greater masses : the one great plan pervading the whole, being, by 



MEANS OF A PERMITTED DESTRUCTION, TO PROVIDE FOR A MORE PERFECT ADAPTATION AND 

 DEVELOPMENT. 



Note (B). 



Of the Nebular Hypothesis of Sir William Herschel. 



On this subject, Sir John Herschel says in his Outlines of Astronomy, (871): — 

 " The first impression which Halley, and other early discoverers of nebulous objects 

 received from their peculiar aspect, so difi"erent from the keen, concentrated light 

 of mere stars, was that of a phosphorescent vapour like the matter of a comet's tail, 

 or a gaseous and (so to speak) elementary form of luminous sidereal matter. 

 Admitting the existence of such a medium, dispersed in some cases irregularly 

 through vast regions in space, in others confined to narrower and more definite 

 limits, Sir W. Herschel was led to speculate on its gradual subsidence and con- 

 densation by the eff'ect of its own gravity, into more or less regular spherical, or 

 spheroidal forms, denser (as they must in that case be) towards the center. 

 Assuming that in the progress of this subsidence, local centers of condensation, 

 subordinate to the general tendency, would not be wanting, he conceived that in 

 this way solid nuclei might arise, whose local gravitation still further condensing, 

 and so absorbing the nebulous matter, each in its immediate neighborhood, might 

 ultimately become stars, and the Avhole nebula finally take on the state of a cluster 

 of stars. Among the multitude of nebulae revealed by his telescopes, every stage 

 of this process might be considered as displayed to our eyes, and in every modifica- 

 tion of form to which the general principle might be conceived to apply. The 

 more or less advanced state of a nebula towards its segregation into discrete stars, 

 and of these stars themselves towards a denser state of aggregation round a central 

 nucleus, would thus be, in some sort, an indication of age. Neither is there any 

 variety of aspect which nebulte off'er, which stands at all in contradiction to this 

 view. Even though we should feel ourselves compelled to reject the idea of a 



