Prof. D. Kirkwood on the Nebular Hypothesis. 179 
the “Parsonstown Leviathan.” As this, however, is a point 
much insisted on by the opponents of the nebular cosmogony, 
we shall endeavor to place it in its proper light. 
The hypothesis that certain nebulz consist of cosmical vapor 
elma condensing around stellar nuclei, was proposed by Sir 
illiam Herschel; that of the genesis of the solar system from 
a primitive nebula was suggested by Laplace. The former re- 
sulted from a critical examination of the nebulz themselves; the 
latter, from a philosophical discussion of the phenomena of the so- 
ar system. Laplace, it is true, adopted the Herschelian theory 
of nebular matter, and regarded it as highly favorable to his own 
hypothesis. Popular writers of the present day, however, look 
upon the former as constituting the entire ground of Laplace’s 
speculations. “ The theory,” says a distinguished author,* “ pro- 
ceeds on the assumption of the existence and wide diffusion of a 
nebulous fluid.” ‘I'he achievements of Lord Rosse’s telescope 
are accordingly claimed as almost decisive evidence against La- 
place's cosmogon 
ow if the mere fact that we have no certain knowledge of 
members of the solar system are now in a fluid state, our own 
1¢) 
rig the components as extremely minute, the nebular pee 
€sis does not appear to have been materially weakened by 
= Rosse’s discoveries, : : 
ora we may remark that comets and the zodiacal light 
the ‘rate the existence of cosmical vapor similar to that which 
ory assumes, 
* 
, dames Buchanan, D.D., LL.D 
shorten Fring the nebule as spherical in form, and not as vastly long vistas fore- 
having their ends turned towards the earth—which would be improba- 
or thése in its remote, much ss gr 
Bi of distance, It t. therefore, be an admitted fact that stars of tl 
Hed and eighth Sinspalteidea gad frresalvablé nebulw may coéxist within limits 
pee comparatively small, and that all inferences in regard to relative dis- 
Tawn from relative magnitudes must be received with caution.”—Bartlett’s 
my, Pp. 2. 
Pherical Ag 29 
