386 COKMIO PHILOSOPHY. [it. it 



known that Sir William TIerscliel supposed certain irresolv- 

 able nebulae to consist of self-luminous vapour hovering 

 cloud-like in space. Laplace associated this hypothesis with 

 his own theory of planetary evolution ; pointing to the pre- 

 sent existence of nebulous masses as confirmatory proof of 

 the past existence of such a nebulous mass as his theory 

 required. According to this view, the irresolvable nebulae are 

 simply starry systems in embryo; and when our planetary 

 system consisted simply of the sun diffused in gaseous form 

 over a circumference of perhaps thirty thousand million miles, 

 it was just like one of these nebulae. But since Herschel's 

 time many nebulae, which he regarded as irresolvable, have 

 been resolved into dense starry clusters. The great nebula 

 in Orion, upon which Herschel placed great reliance, was 

 resolved both by Lord Eosse's reflector and by our Harvard 

 refractor ; and the suspicion began accordingly to arise that, 

 if our telescopes were only powerful enough, there might 

 prove to be no irresolvable nebulae at all. Hence many 

 writers thoughtlessly hastened to proclaim that the nebular 

 theory had lost its chief support, forgetting that the over- 

 whelming evidence furnished by the comparatively well- 

 known structure of the solar system must take precedence of 

 any hypothesis as to the character of remote and less-known 

 sidereal phenomena. Mr. Chambers, in giving an account of 

 the resolution of the " dumb-bell " nebula in Vulpecula, 

 rather gleefully wrote the obituary of the nebular hypothesis ; 

 but like many other obituaries, this one turned out to be 

 premature. For now came Mr. Huggins, with his spectro- 

 scope, and proved once for all that the wary and sagacious 

 Herschel, who hardly ever made a false step, was right, here 

 as elsewhere. In 1864 Mr. Huggins analyzed the light sent 

 from a nebula in Draco, and found it to contain the bright 

 lines which are sure evidence of the gaseous condition of the 

 luminous body. Since then several other nebulae have been 

 proved to be gaseous ; so that the question may now be 



