PT. i. Astronomy and Geology compared. 43 



volcanoes are not extinct, and the sea is constantly 

 receiving the deposits brought by rivers into its 

 beds. 



In following the footsteps of Buckland and 

 Murchison, Oflren, Cuvier, or Lyell, and the many 

 other distinguished Geologists whose names will occur 

 to us, we reverence the intellect and sagacity which 

 in the course of less than a century has opened a 

 new field of science to our inquiries. Yet in pur- 

 suing the tracks left by these enlightened minds we 

 are often tempted to regret the loss of those two 

 great aids to Astronomy pure Mathematics and the 

 assistance of the Telescope, and the observation of 

 bodies actually existing before our eyes. The Geo- 

 logist gropes comparatively in the dark; and the 

 greatest caution is necessary before we adopt con- 

 clusions founded upon the evidence of facts alone, 

 and of facts so buried in the depths of time. How 

 much has perished ! how small a residuum has 

 escaped the ravages of the Great Destroyer upon 

 which to rear our geological structure ! Yet how 

 careful ought the true philosopher to be in sub- 

 stituting hypothesis, however plausible, for the sole 

 proof he can adduce the evidence of facts or in 

 supplying by the same means the hiatus so often 



