TRANSLATOR'S INTRODUCTION XXXIX 



his first great discovery in Physical Astronomy, 

 namely, the Retardation of the Rotation of the 

 Earth by the action of the Tides. 



IV. KANT'S DISCOVERY OF THE RETARDATION OF 

 THE ROTATION OF THE EARTH. 



The subject propounded by the Berlin Academy 

 for the Prize Essay of 1754 was this: ' Whether the 

 Earth in its Rotation round its Axis, by which it 

 brings about tJie alternation of day and night , has 

 undergone any alteration since the first period of its 

 origin. What may be the cause of this, and what 

 can make us certain of it?' The Transactions of 

 the Academy give us no light on this subject. 

 They furnish no hint as to how the question arose; 

 nor as to whether any competitive essays were sent 

 in, or any decision given. Indeed, they contain no 

 reference to the subject at all. All our information 

 concerning it is derived from Kant alone. He was 

 just then engaged in working out his Cosmogony 

 and writing his Natural History and Theory of 

 the Heavens, and when he came to the point at 

 which this question was relevant to his speculation, 

 he passes it by with a reference to the problem 

 set by the Royal Academy of Science, reserving 

 his solution on that account meanwhile (see infra 

 pp. 107-8). It may be that Kant's mind had been 

 working on this very subject, or that the statement 

 of the problem had also suggested to him his 



