BOOK NOTICES, 503 
formation, on the evolutions of nebulse, stars, and planets, on the all-important 
influence of tidal-action in cosmic history, and on the grand cycle of cosmic ex- 
istence.'' 
It is divided into four parts : I. World Stuff with chapters upon Cosmica,! 
Dust and Nebular Life. 11. Planetology, subdivided into essays upon the 
Origin of the Solar System, the General Cosmogonic Conditions on a cooling 
Planet, Special Planetology or Present Conditions and Cosmogonic History of 
the Planetary Bodies in our System, Planetary Decay or Cosmic Conditions 
more advanced than the Terrestrial Stage, Habitability of other Worlds. III. 
General Cosmogony, which includes discussions of the fixed Stars and Nebulse, 
and of the Cosmic Cycle. IV. Evolution of Cosmogonic Doctrine, with an 
interesting account of Pre-Kantian Speculations, Kant's General History of Na- 
ture, Doctor Lambert and Sir William Herschel, and LaPlace's System of the 
World. 
In presenting many of his theories Professor Winchell undoubtedly is entitled 
to the credit of having preceded many of his contemporaries, at least in his pub- 
lic lectures. For instance, he enunciated the theory of the vast quantity of cos- 
mical or meteoroidal matter and its influence upon planetary motions some years 
before the investigations of Nordenksjold, Tissandier, and others. On the^ 
geology of the Moon his reasonings were in writing considerably before M. 
Faye's memoir appeared in which some coincident conclusions were reached 
without covering the same ground. He also first pointed out the importance of 
the atmospheric factor and the ice-clad condition of the ultrajovian planets. 
He has made an effort to clear up the most serious difficulties encountered 
by belief in the nebular origin of the planetary system, for which he has stood 
up for many years, and of which he says, "the great idea was fascinating, its 
magnificence took possession of the imagination and its symmetry and coherence 
commanded rational conviction. It now commands the admiration and ciiam- 
pionship of the scientific world." Monographic summaries of various scientific 
<ioctrines, such as replies to objections to the nebular theory, views upon cosmi- 
cal matter, estimation of the earth's age, etc., occupy a number of pages and are 
also full of original suggestions. 
Copious foot notes give not only full bibliographical references and authori- 
ties, but in many instances mathematical operations, showing the author's pro- 
cesses ; at the same time the text may be read separately for a logical treatment 
of the subject without following it into obtruse and recondite depths. 
It is impossible to touch upon one in a hundred of the salient points in this 
work, and still we hope we have said enough to show the reader that it is one of 
powerful vigor, deep research and profound thought; worthy of the author, even, 
after all his other works, and instructive and suggestive to students of every de- 
gree. The publisher's work has been well done, and nothing is lacking to make 
the book attractive in appearance. 
VI 1-32 
