THEORY OP THE EARTH. 33 



18. Of Astronomical Causes of the Revolutions on 

 the Surface of the Earth. 



The pole of the earth moves in a circle round 

 the pole of the ecliptic, and its axis is more or less 

 inclined to the plane of the ecliptic; but these 

 two motions, the causes of which are now ascer- 

 tained, are confined within certain bounds, and 

 are much too limited for the production of those 

 effects which we have stated. Besides, as these 

 motions are exceedingly slow, they are altogether 

 inadequate to account for catastrophes which must 

 necessarily have been sudden. 



The same reasoning applies to all other slow 

 motions which have been conceived as causes of 

 the revolutions on the surface of our earth, chosen 

 doubtless in the hope that their existence could not 

 be denied, as it might always be asserted that 

 their extreme slowness rendered them impercepti- 

 ble. But it is of no importance whether these as- 

 sumed slow motions be true or false, for they ex- 

 plain nothing, since no cause acting slowly could 

 possibly have produced sudden effects. 



Admitting that there was a gradual diminution 

 of the waters; that the sea might take away solid 

 matters from one place and carry them to another; 

 that the temperature of the globe may have dimi- 

 nished or increased; none of these causes could 



