546 THE POPULAR SCIENCE MONTHLY 



The work from which Kant quoted a justification of Descartes's enter- 

 prise — and, by implication, of his own — the " Universal History " 

 (1736-65) appeared in an (incomplete) German translation in 174.4. 

 This huge historical compilation, one of the great publishing enterprises 

 of the time, contained an introduction of (in the German edition) over 

 one hundred pages devoted to the subject of cosmogony, giving the the- 

 ories of the Greek philosophers, of Descartes, Burnet, Whiston and other 

 moderns, and a new hypothesis of the author's own. In 1749 the first 

 volume of a still more celebrated, and scarcely less voluminous, publica- 

 tion — Buffon's " Histoire Naturelle " — saw the light. This volume was 

 chiefly devoted to a " history and theory of the earth," with a chapter 

 on the formation of planets which contained ideas more closely related 

 than those of Kant to the nebular hypothesis. Buffon remarked upon 

 the peculiar uniformities of the solar system which seemed to call for a 

 mechanical explanation, but which gravitation alone did not account 

 for, viz., the revolution of all the planets in the same direction, approxi- 

 mately in the same plane, and in nearly circular orbits. Buffon's own 

 explanation of these phenomena in his " Theorie de la Terre " of 1749 

 is given in the following passages : 



This uniformity of position and direction in the movement of the planets 

 necessarily presupposes some common factor in their original movement of 

 impulsion, and makes us suspect that it has been communicated to them by one 

 and the same cause. . . . This impulsive force was certainly imparted to the 

 stars in general by the hand of God when he set the universe in motion. But 

 since, in physical science, we ought to abstain so far as possible from having 

 recourse to causes outside of nature, it seems to me that in the solar system we 

 can account for this impelling force in a sufficiently probable manner and in 

 accordance with the principles of mechanics. . . . May it not with some proba- 

 bility be imagined that a comet falling upon the surface of the sun may have 

 separated from that body certain parts, to which it has communicated a move- 

 ment of impulsion in a common direction? . . . The planets would thus have 

 formerly belonged to the sun, and would have been detached from it by an 

 impelling force, common to all alike, which they still retain. 18 



Buffon was the only one 14 of his precursors (of the post-Newtonian 

 period) known to Laplace. He made this passage of the " Histoire 

 Naturelle " the starting point of his own earliest exposition of his 

 nebular hypothesis, in the concluding chapter of the " Systeme du 

 Monde." The hypothesis of Buffon, he remarked, accounted for most 

 of the non-gravitational peculiarities of planetary motion that require 

 to be accounted for; but since there remained certain other such phe- 

 nomena which Buffon's supposition could not explain, a new hypothesis 

 must be devised. 



Finally, in the same year, 1749, a generation after its famous 



""Histoire Naturelle," first ed., I., pp. 131-133. Kant had read Buffon 

 before writing his own cosmogony; see "Universal Natural History," Pt. II., 

 ch. 2. 



14 Cf. " Systeme du Monde," first ed., 1796, II., p. 298. 



