1022 Recent Literature. [October 
when a generally accepted theory has been weakened by the pres 
entation of an array of objections, he does much for science why _ 
shows that these objections, valid perhaps against the first cru 
form of a theory, do not really invalidate it, though they may 
render necessary some modification and addition. This is 
cisely what Professor Winchell performs, in this ably written vok | 
. ume, for the well-known nebular theory of Laplace, which hasa 
late years been attacked by a series of objections, such as the ex- 
istence of retrograde motions; the length of the periodic times 
the planets, which have been stated to be in some cases longerjia 
others shorter than the nebular theory allows; the absence of an 
adequate cause for rotary motion; the want of coincidence in the 
planes of the planetary orbits, their ellipticity, and their distance 
from each other. To these objections are added others based 
upon the relations of the planetary masses and densities; the 
geologist’s objection that his science shows that more time than 
the nebular theory allows has been occupied by the earth in 
arriving at its present condition; and various others based on the 
relations of comets, stars and nebulz. : 
Without disputing that these objections are fatal to the idea of 
nebulous matter contracting into rings, and ultimately into worlds | 
1 dust, or meteors, tt 
d nebulæ of varits 
kinds. The universe is supposed to be eve 
with the crude material out of which worlds are forme 
ideas of Newton, Humboldt, Williams, and Siemens are ire 
Then follows the theory that swarms of small er abot 
matter, circling in numberless orbits, and in all p about the 
th the planetary ols 
Profe i ‘te if not entirely new: -| 
ssor Winchell as not yet trite, if n aa hel bridge 
