414 



NATURE 



[February 28, 1901 



Kant's announcement of the appearance of his cos- 

 mogony is found in a paper which he wrote, discussing a 

 possible alteration in the time of the earth's axial rota- 

 tion. We doubt if anything like justice has been done 

 to Kant's memory in connection with this discussion. 

 He there pointed out, in the clearest possible manner, two 

 important facts which in recent times have received very 

 considerable attention, and the early mention of which 

 by Kant discloses a far-reaching apprehension of the 

 operations of celestial mechanism. One is the view 

 revived by Delaunay at the time of the controversy 

 concerning the amount of the secular acceleration of the 

 moon's motion, that the action of the tides must tend to 

 diminish the time of the earth's rotation. The other is, 

 that the explanation of the fact that the moon, in revolving 

 round the earth, turns to it always the same hemisphere, 

 can be traced to tidal influence. But if these two bold 

 speculations have not met with the attention to which 

 they are entitled, Kant himself was not a little to blame for 

 this neglect. For he subsequently adopted the notion 

 that the daily rotation of the earth was accelerated by 

 the falling of heavy particles from the solid crust of the 

 earth towards the centre, supposed to be fluid, and such 

 particles carrying with them a greater velocity of rotation 

 than the lighter particles which might be ascending from 

 the centre. It is, perhaps, of no great consequence to 

 point out here that modern analysis tends to the con- 

 clusion that our globe is solid throughout, but it is not a 

 little curious to notice that Kant did not seem to appre- 

 hend that the introduction of a second hypothesis does 

 not in any way affect the validity of the former argument. 

 The possibility of the two causes operating together, and 

 the ultimate effect depending upon the amount of their 

 difference, does not seem to have occurred to him. But 

 the paper as it stands in the text betrays a feverish, 

 unphilosophical hurry. The argument is marred by 

 misdescriptions that would have been eliminated by the 

 exercise of more care, and one might well doubt whether 

 Kant fully appreciated the importance of his own sug- 

 gestions. 



But in the presentation of his cosmogony, properly 

 so-called, he lavished all the care and skill of which 

 he was master. Laplace hid his suggestion of the 

 nebular hypothesis away at the end of a volume as 

 though he were ashamed of it, or was afraid that the 

 introduction of more or less hypothetical matter might 

 damage the effect of his rigorous demonstrations. Kant, 

 on the other hand, believing that he was writing a classic 

 for all time — perhaps he was — felt himself entitled to 

 dedicate his work to his sovereign, and was content to base 

 his reputation on the legitimacy of his hypotheses and 

 the use he made of them. But mankind has, perversely 

 enough, connected the nebular hypothesis with the name 

 of Laplace rather than with that of Kant. 



To Thomas Wright, of Durham, the author, according 

 to Prof. G. H. Darwin, of a book of preternatural dul- 

 ness, Kant is indebted for his general view of the con- 

 struction and arrangement of the Milky Way. Whatever 

 merit or originality the "grindstone theory" possesses, 

 the credit of its discovery seems to be undoubtedly due 

 to this author, and the additions that Kant attached to 

 the description are not particularly happy. For he not 

 only regarded the nebulas as presenting distant views of 

 remote galaxies and constellative systems in which the 

 NO. 1635. VOL. 63] 



construction of our Milky Way was repeated, but he 

 created a central sun about which each star had its 

 appointed orbit, and around which it would run its course 

 during endless ages. We cannot, therefore, follow Prof. 

 Hastie in his assertion that Kant " improved and simpli- 

 fied Wright's theory, giving it a more exact scientific 

 expression " (p. Ixviii). Nor are we prepared to admit 

 that " spectroscopic results are so far in entire harmony 

 with Kant's view, and have only extended its range and 

 certainty " (p. c). Spectroscopic observation has not 

 supported the conclusion that nebute are due to the com- 

 bined light of distant suns, so remote that the light from 

 them, condensed into a small space, is visible to us as a 

 tiny luminous cloud. In this place it is sufficient to refer 

 either to the philosophic views held by Schiaparelli, or 

 the more complete examination of these bodies of which 

 an account has been given by Sir Norman Lockyer. Nor 

 is it probable that the stars, collected as they are into 

 irregular clusters or masses with comparatively vacant 

 spaces between them, constitute a stable system. There 

 is no evidence of the existence of a central body of vastly 

 greater mass than the stars surrounding it, which is 

 almost an essential feature to the maintenance of such a 

 system. 



But it may be urged that Kant's greatest success is to 

 be found in his construction of the solar system. In the 

 bold conception 



" I assume that all the material of which the globes 

 belonging to our solar system — all the planets and comets 

 — consist, at the beginning of all things was decomposed 

 into its primary elements and filled the whole space of 

 the universe in which the bodies formed out of it now 

 revolve" (p. 74), 



he anticipated Laplace in the essential portion of the 

 nebular hypothesis, and though his conception is marred 

 by one great dynamical error, yet possibly his origin of 

 the cosmos comes nearest to that at present held by the 

 greatest authorities. If Kant's theory be maintained in 

 detail it would seem to lead, not to a planetary system, 

 such as at present exists, but to a central sun formed by 

 the collection of all the matter in the " meteoritic 

 plenum." But this may be a quite possible condition at 

 one stage of the process, just as Laplace's hot rotating 

 nebula, with which his hypothesis starts, may represent 

 a later stage. For Lord Kelvin is understood to trace 

 the solar system to an originally 



"cold nebula consisting of separate atoms or of meteoric 

 stones initially possessed of a resultant moment of 

 momentu^n equal to that of the solar system. Collision 

 at the centre will reduce them to a vapour, which then 

 expanding far beyond Neptune's orbit will give a nebula 

 s uch as Laplace postulates." ^ 



But Kant's great error consists in the assumption that 

 a motion of rotation could be produced from a state of 

 rest by repulsive forces acting upon the rarer masses of 

 the condensing matter, which would give rise to a whirl- 

 ing motion. This is to ignore the fact that the sum total 

 of rotatory motion in a system can never be increased or 

 diminished by the mutual action of its separate parts. 



It is needless to dwell on such points as the suspected 

 increase of eccentricity in planetary orbits with increase 

 of distance from the sun, or the explanation offered foi 

 the varying densities of the planets with the variations of 



1 G. F. Becker, " Kant as a Natural Philosopher," American Journal of 

 Science, vol. v., February 1898. 



