6 5 o THE POPULAR SCIENCE MONTHLY. 



Gentlemen, I have restricted my remarks to a few divisions of the 

 general subject of the importance of the cultivation of science, and 

 leave it to others to develop other points of the same subject in their 

 bearing on the welfare of man. 



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TILE NEBULAR HYPOTHESIS. 



By JOHN LE CONTE, M. D., 



FItOFESSOB OF PHYSICS IK THE UNIVERSITY OF CALIFORNIA. 



THE speculative views of Lambert and Kant led them to the adop- 

 tion of a Nebular Hypothesis, and to the idea of a perpetual 

 development in the regions of space. Sir William Herschel, after long 

 hesitation, was ultimately led, by the surer path of observation and 

 cautious induction, to the adoption of similar views, in relation to the 

 existence of a seK-luminous substance of a highly-attenuated nature, 

 distributed through the celestial realms. At a later period, in 1811, 

 he communicated to the Royal Society an exposition of his famous 

 hypothesis of the transformation of nebulae into stars. 



Sir William Herschel made no attempt to extend his hypothesis to 

 a cosmogony of our solar system. If, therefore, the " Nebular Hy- 

 pothesis " is restricted to the theory which professes to explain the 

 genesis of our solar system, it is only analogically related to the loftier 

 speculations of Sir William Herschel, in regard to the processes of 

 star-formation going on in the stellar realms. In this restricted sense, 

 the " Nebidar Hypothesis " is due to Laplace. This illustrious math- 

 ematician, with a modesty and diffidence befitting a true philosopher, 

 endeavored to lay rational foundations for a cosmogony of the solar 

 system. This sublime speculation has been egregiously misunderstood 

 and misrepresented alike in itself and in its tendencies. 



The lecturer proposed to disconnect Laplace's Nebular Hypothesis 

 from the question of the general diffusion of cosmical vapor in the 

 celestial regions. Indeed, the origin of Laplace's hypothesis did not 

 lie in Herschel's speculations in relation to the transformation of neb- 

 ula? into stars and clusters of stars. In contemplating our solar sys- 

 tem, he discerned numerous harmonies and adjustments, which were 

 not accounted for by the law of gravitation, which induced him to infer 

 that all its members were of one family of a common origin. The 

 Nebular Hypothesis was framed to explain and coordinate these facts, 

 and, if possible, to refer them to established mechanical principles. 

 Under this view, the lecturer considered the Nebular Hypothesis in 

 two aspects viz. : As a pure hypothesis, framed to explain the arrange- 

 ments of the solar system ; and as a physical reality, indicating the 

 actual process by which the phenomena were evolved or produced. 



