LITERARY NOTICES. 



127 



the Colombos were numbered. Even the 

 house in which the family lived is pointed 

 out. Then follows the story of Columbus's 

 journey to Portugal, his weary waiting in 

 Spain, his voyages, discoveries, misfortunes, 

 and last days spent in pleading with the un- 

 appreciative Ferdinand. The tale is related 

 in very simple but graphic fashion, with 

 many touches of humor, while the varied 

 illustrations constantly keep fresh the flavor 

 of the time. Only those anecdotes are given 

 that come from authentic sources, and the 

 recent labors of Mr. Henry Harrisse and 

 Signer Stalieno have added so largely to 

 the fund that there are enough to make the 

 narrative sufficiently life like. No attempt 

 is made to screen the failings of Columbus 

 his pursuit of wealth, his curious theories, 

 and the evil which is chargeable to him as 

 an exponent of his time, the establishment 

 of slavery in the New World. On the other 

 hand, these are not enlarged until they ob- 

 scure his courageous project and unflagging 

 zeal. He still remains " the most conspicu- 

 ous figure in the history of his age." He 

 crossed the sea of darkness, and we rightly 

 honor him for his great achievement. 



THE VISIBLE UNIVERSE. By J. ELLARD GORE, 

 F. R. A. S. London : Crosby Lockwood 

 & Son. New York: Macmillan & Co. 

 Pp. 346. Price, $3.75. 



ALTHOUGH astronomers have not yet 

 solved the problem of celestial construction, 

 the author of this volume refrains from add- 

 ing any new conjecture to the list. He ex- 

 amines critically all the explanations worth 

 serious mention, and this task may well have 

 served to keep him within the dry land of 

 fact. Besides the theoretical discussions, the 

 book contains the latest observations of the 

 position of stars and nebulae and, so far as 

 known, their motions and chemical compo- 

 sition. 



Five principal objections have been 

 brought against the nebular theory ; most of 

 these have been well answered by M. Roche. 

 According to M. Wolf, two points are yet un- 

 determined how large planets were formed 

 from the nebulous mass, and how the equa- 

 torial and orbital inclinations were produced. 

 M. Faye, however, finds the fifth objection 

 the retrograde motion of the satellites of 

 Uranus and Neptune destructive of La- 



place's theory and advances another hy- 

 pothesis in his work, Sur 1'Origine du Monde, 

 with which Mr. Gore agrees. In this he as- 

 sumes that the earth was formed before the 

 sun, and that its internal heat sufficed for 

 the evaporation of water and for the uni- 

 form vegetation that existed for aeons of 

 time. Laplace did not explain the origin of 

 the primitive nebula, therefore Dr. Croll con- 

 sidered the hypothesis incomplete and fur- 

 nished a cause in his impact theory. Two 

 dark bodies endowed with enormous veloci- 

 ty collided in space and produced a perfect 

 nebula ! 



A contention which promises no settle- 

 ment is the duration of the sun's heat in past 

 time. Noted physicists allow only twelve 

 millions of years as the maximum period on 

 the gravitation theory. This is insufficient 

 for the geologists, who demand a hundred 

 millions for the denudation of rocks. Dr. 

 Croll's careful estimate is ninety millions ; 

 while biologists ask for a still longer period 

 for the evolution of species. Most astrono- 

 mers concur in the theory of Helmholtz that 

 the heat of the sun is caused by the shrink- 

 age of its mass through gravitation. To this 

 philosopher also is due the vortex-ring idea 

 that matter consists of whirling portions 

 of the luminiferous ether. This wondrous 

 fluid, supposed to fill interstellar space and 

 act as a medium for the transmission of 

 light, is enormously elastic and wholly un- 

 like matter, since planetary motion is not 

 retarded by it as it would be by the most 

 attenuated gas. 



The spectroscope, which has revealed so 

 much of the constitution of the stars, shows 

 also another defect in the nebular theory, 

 unless chemists may come to the rescue. 

 The spectra of various nebulae give only hy- 

 drogen and one other unknown element. If 

 the solar system was evolved from a nebu- 

 lous mass by condensation, whence the dozen 

 elements of the sun and the sixty-five of our 

 own planet ? It has been suggested that all 

 our elements may be further resolved into 

 one original element. In anticipation of its 

 discovery this has been named protyle. 



Lockyer's hypothesis was that the upper 

 reaches of the atmosphere contained parti- 

 cles of magnesium, manganese, iron, and car- 

 bon, and that nebulae were swarms of mete- 

 oritic dust His observations in regard to 



