1 KANTS UNIVERSAL NATURAL HISTORY 



2. DR. REUSCHLE ON KANT'S MATHEMATICAL 

 CALCULATION. 



It has been already remarked that Kant's calculation of 

 the rate and amount of the Retardation of the rotation of the 

 Earth by the action of Tidal Friction is much too great. 

 We may here quote in illustration what Dr. Reuschle says 

 on this point, which he has carefully considered, his Foot- 

 notes being put in brackets. ' Kant even seeks by an 

 approximate calculation to estimate the amount of the 

 retardation, which he finds to be for every second equal to 

 the weight of a body of water of 237 \ million cubic feet, 

 and which is exceeded by the volume of the Earth "123 

 billion times." He reasons from this to the time in which 

 the whole axial rotation of the Earth would be "exhausted" 

 as he peculiarly expresses it by the resistance ; and by 

 this he means the time in which the retardation would 

 amount to as much as the time of rotation itself had been 

 at the beginning of the period, i.e., one day with which, 

 however, the axial rotation itself is by no means "exhausted," 

 as Kant comes afterwards to say towards the end of his 

 discussion. He finds two million years ; i.e., after the close 

 of that time one rotation of the Earth would last two of our 

 present days, and a year would contain only half as many 

 rotations, or days, as at present, and from this there follows 

 for a period of two thousand years, an increase of the day by 

 86 seconds. (Or as Kant expresses it; after 2,000 years, 

 the year will contain 8J hours less, i.e., the year will be past 

 before the last 8J hours of the 365^ day has flown; 

 for 365 times 86 seconds = 8J hours.) This result is 

 evidently much too great even on Kant's standpoint; 

 specially because in dealing with the question of the time, 

 he commits an essential error in that he does not calculate 

 according to correct mechanical principles, the force of the 



