356 Edwin B. Frost 



These discoveries, which were merely waiting for the optical 

 power necessary for their revelation, profoundly affected the 

 mental attitude of the intellectual people of the times, when the 

 new knowledge had been diffused. A new place was given to the 

 planets, in their relation to the earth, and a less exalted status in 

 the solar system was the logical consequence for the earth. With 

 its increased, but uncoordinated knowledge, science was awaiting 

 its Newton; but it was almost reluctantly that he gave from his 

 Btore of knowledge, and we must not forget the great credit due 

 to Ednuuid Halley for persuading Newton to present the princi- 

 ples he had formulated to the Royal Society. Not only this, but 

 Halley undertook the publication, finally at his own expense (when 

 the coffers of the Royal Society were found to have been drained 

 by other undertakings) of the immortal Principia of Newton. 



The great impetus thus given to mathematical research, fos- 

 tered in many cases by monarchs whose other contributions to the 

 uplift of humanity were few, brought brilliant results, and gave 

 the means and methods which led to such a great generalization 

 as that of La IMacc. We nuist not forget the earlier and independent 

 philosophizing of Wright of Durham, and of Immanuel Kant of 

 Konigsberg. I^a Place, however, had the mathematical skill and 

 genius to estal)lish many of his conclusions upon a rigid founda- 

 tion of demonstration. But, in many respects, the generaliza- 

 tion of the Nebular Hypothesis outreached observations and math- 

 ematical proof. His mind aj^pears to have leaped over barriers 

 which might soberly have been regarded as unsurmountable. He 

 had probably himself hardly seen a spiral, or even a ring nebula. 

 It was beyond the I'oach of the imagination that men would some 

 day know the chemical constitution of the sun, still less that of the 

 vastly more distant stars and nebulae. 15ut of course the re- 

 searches of Messiei- (Louis Fifteenth's ''Ferret of Comets") and 

 the splendid investigations of William Herschel, who in 1786 gave 

 to the Royal Society his gi-eat catalogue of 1000 nebulae, were 

 available to La l^lace. 



Five years before the publication of the Systeme du Monde, 

 which is dated 1796, Herschel, in 1791, had propounded the view 

 that the nebulae diff"ei-e(l in nature from the stars. Ui)on this 

 view he founded his theory of stellar evolution. It has a familiar 

 sound to us now, quite in line with the expanding thought of the 

 last half century. His development of the idea was ai)j)arently 



