Contribution of Astronofny to General Culture 357 



quite independent of the theory of Lii Place, which was pubhshed 

 between successive papers of Herschel. He early registered his 

 view that the self-luminous matter of the nebulae was ''more fit 

 to produce a star by its condensation than to depend on the star 

 for its existence." He arranged in an orderly series the different 

 objects he had discovered and found ''perhaps not so much differ- 

 ence as would be in an annual tlescription of the human figure, 

 were it given from the birth of a child till he comes to be a man in 

 his prime." This reference to the evolution theory of Herschel 

 is niatle here as a matter of justice; but he is far better known by 

 his many observational discoveries than by his speculation, while 

 La Place is doubtless better known for his Nebular Hypothesis 

 than for his splendid work, the Mecanique Celeste. 



The impress of the hypothesis of La Place upon the culture of 

 the nineteenth century has been profound. What collegian has 

 escaped the grandeur of the conception of so complicated a result 

 as our solar system developing under comjKiratively simple laws? 

 To have this conception brought distinctly to the attention of 

 the student is, to my thinking, almost argument enough for mak- 

 ing astronomy a required study in college. 



Here let me answer in advance the question often asked of the 

 practical astronomer or astrophysicist: Is the hypothesis of La 

 Place now obsolete, and discarded, or supplanted l)y views better 

 in accord with modern research? My answer would be in the nega- 

 tive, and I know that this view is shared by many of my friends 

 whose opinion I value. It is true that this theory of La Place is 

 inadequate in some respects, and is mathematically unfounded in 

 some particulars. Its premises need modification, and it also 

 leaves much unexplained. But no adecjuate substitute has been 

 proposed, and the increased study of the different phases of devel- 

 opment, as inferred from stellar spectra, supports the La Placean 

 theory surprisingly. 



Let us pass to another of the great scientific discoveries of the 

 nineteenth century, crystallizing in the decade when The Origin 

 of Species appeared. I refer to the intei-pretation of celestial spec- 

 tra. From the beginning of the century, the existence of dark 

 lines in the solar spectrum had been known, and as early as 1817 

 Fraunhofer had examined with the j)nsni the light from some of 

 the stars and planets. The double dark line in the solar spectrum 

 (known as D) was known to coincide closely with the bright line 



