liv KANT'S UNIVERSAL NATURAL HISTORY 



only considerably greater than the empirical result, it follows 

 that a considerable part of the resisting force must be spent 

 in compensation of an opposite cause, which would shorten 

 the time of the Earth's rotation. Mayer finds this opposite 

 cause in the diminution of the volume of the Earth, in con- 

 sequence of the excess of the radiation of its own heat over 

 the inflow of heat from the Sun. We cannot, however, enter 

 further here on the numerous considerations and facts which 

 Mayer adduces in the last chapter of his Dynamics of the 

 Heavens to corroborate this view of the net loss of the Earth 

 in heat-, but the weight of his considerations is certainly not 

 to be under-estimated.' J 



3. KANT'S DISCUSSION OF THE AGEING OF THE EARTH. 



Later in the same year 1754, Kant contributed another 

 paper to the same Konigsberg journal, which was entitled, 

 'The question: Whether the Earth grows old? physically 

 considered.' It appeared in sections, from Dumber 32 to 

 37, and therefore in August and September, I754- 2 This 

 discussion shows the same original and suggestive insight on 

 the part of Kant, although it is less definite in the way of 

 positive result. Its value seems to me to be generally 

 underestimated by its critics. It is really the first clear dis- 

 cussion of the method of determining the age of the Earth by 

 observation of its actual changes as now going on ; and it 

 presents a distinct view of the universal significance of the 



1 ' Kant und die Natunvissenschaft. ' Deutsche Vierteljahrs-Schrift. 

 No. cxxn., 1868. Pp. 76-80. 



^Konigsberg Wbchentliche Frag- und Anzeigungs-Nachrichte)i, Jahr- 

 gang, I754> Stuck 32-37. Reprinted in Nicolovius' Sanunlung, S. 

 91-120, and in all the complete editions of Kant's Works. Cf. 

 Borowski, I.e. 48-49. Here again V. Kirchmann in his Erlduterungen, 

 does scant justice to Kant. Kant's discussion seems to me well worthy 

 of translation, and some day it may be translated. 



