174 The Nebular Hyp'dhesis : Its Present Condition. 



Avas in its fullest force, we sliould go back beyond the days of Homer, 

 beyond the age of man, backward to Ihat indefinite period when the 

 gaseous envelope of the earth segregated its component elements, 

 formed new combinations, threw back upon the earth its rejected ex- 

 halations, or showered upon it the superabundant material it had 

 accumulated from surrounding space, or had evolved from the chem- 

 ical trituration of its own inharmonious forces. 



The Nebular Hypothesis: Its Present Condition. By John J. Plum- 



MER, M.A. 

 From the Popular Science Review (Eiig.) 



In the whole range of science there is no theory Avhich has attracted 

 so much attention, has passed through so many vicissitudes, and has 

 been so earnestly and fondly supported in the face of opposing evi- 

 dence, as the nebular hypothesis of Lajjlace. This has arisen, doubt- 

 less, to some extent from the respect due to the very eminent astrono- 

 mers by whom it was first suggested and promulgated, but perhaps 

 still more to the nature of the hypothesis itself, and to the fact that 

 many otherwise unexplained phenomena find in it a satisfactory solu- 

 tion. The whole course of scientific progress has led us to look for the 

 most simple laws in order to explain the most apparently complicated 

 results ; and such a law the nebular hypothesis would become, were it 

 possible to give to it such a high degree of probability as at present 

 serves for the demonstration of the Newtonian law of gravitation, or 

 of the undulatory theory of light. That it may one day attain to this 

 degree of certainty, and be recognized as an established truth, is the 

 hope of many who are fascinated alike by its simplicity and its com- 

 prehensiveness — a hope that has often served to sustain it when the 

 bulk of evidence has not appeared to be in its favor, and one in which 

 the writer to some extent indulges, although well aAvare that it may 

 require to undergo considerable modification before it reaches that ex- 

 alted position. 



Previously to the revelations of the spectroscope, the nebular hy- 

 pothesis stood at a very low ebb. The gradually increased powers of 

 telescopes, culminating in the gigantic reflector of Lord Rosse, had one 

 by one reduced the nup?ber of the so-called nebulffi, by resolving them 

 into clusters of distant stars, very closely packed together, until, al- 

 though a large number still continued nebulous in appearance under 



