G. F. Becker — Kant as a Natter al Philosopher. 105 



that the greater part of the material of the nebula acquired 

 by impacts only a very small tangential velocity, and thus fell 

 directly into the central mass. This fallacious explanation 

 arose from his incorrect view of the generation of moment of 

 momentum. 



Further light as to the origin of the heat of stellar bodies 

 came to Kant in 1785, thirty years after the publication of his 

 theory of the heavens. Adair Crawford, in 1779, published 

 his experiments on the development of heat by the compres- 

 sion of gases. These discoveries Kant says indicate a method 

 of making comprehensible the development of any degree of 

 heat as an accompaniment of the formation of heavenly bodies 

 (suns or planets) from the initial nebula. He points out that 

 the increase of temperature depends upon the initial and final 

 densities and upon the brevity of the time of condensation. 

 He infers that the central body, on account of its greatest mass 

 and attraction, must develop the greatest heat and is rendered 

 capable of being a sun.* 



Comets in Kant's system are derived from the extreme por- 

 tions of the nebulous mass which gave rise to the solar system. 

 The original position of the cometary matter being at so vast 

 a distance from the center, gravitation acted but feebly ; elastic 

 impact of the gravitating material was therefore also feeble ; 

 the mass acquired but little tangential velocity and the result- 

 ing orbits show correspondingly great eccentricity. The feeble- 

 ness of attraction and the tenuity of the mass at the exterior of 

 the nebula may account for the independence of the elliptic 

 manifested by comets; but Kant expresses his own dissatisfac- 

 tion with this explanation. Retrograde comets Kant hardly 

 attempts to explain ; he even thinks there may be an optical 

 illusion. f Kant supposed the eccentricity of the planets to 

 increase with distance from the sun, and predicted that planets 

 with greater eccentricity than Saturn and at greater distances 

 from the sun would be discovered.^ These in his opinion 

 would form in a sense a transition to cometary bodies. 



Kant considers the end of the solar system as well as its 

 inception. The world itself is doomed to destruction as a hab- 

 itable planet by the process of base-levelling and consequent 

 flooding by the ocean. § All the planetary bodies will eventu- 

 ally fall into the sun, the inner ones first, in consequence of the 

 universal tendency of motion to gradual retardation. While 

 Kant had a perfectly clear idea of the retardation of the motion 



* Ueber die Vulcane im Monde 1785: Kant's Werke, vol iv, p. 201. 

 f Kant's Werke, vol. i. p. 265. 

 i Ibid., p. 243. 



§ The process of base-levelling is excellently described in the paper " Ob die 

 Erde veralte?" 1754, Kant's Werke, vol. i, p. 203. 



