A GRASP OP GEOLOGIC TIME. 153 



elemental contest we behold the scenes of the undisputed 

 reign of fire, when the terrestrial globe was a self-lumi- 

 nous orb. And yet deeper in the infinitudes of the past we 

 are forced to contemplate the matter of the earth and of all 

 her sister planets a blended blaze of ethereal flame. While 

 we stand paralyzed and wondering in the presence of such 

 unmeasured flights of time, the geologist, the astronomer 

 and the physicist open their mouths in unison to assure us 

 that, from the beginning to the end, this mass of matter 

 has been wasting its heat in infinite space as fast as the 

 wings of ether could bear it away; and that every phe- 

 nomenon of terrestrial history, from primordial light to 

 the last spring tempests, has been only a consequent or a 

 concomitant of this progressive cooling. And when we ask 

 how long the duration of this work, they reply that the 

 earth has cooled only one- fourteenth of a degree in the 

 last twenty-five centuries. 



Even when we narrow our observations down to the 

 compass of the closing events of terrestrial history, we 

 stand amazed before the revelation of eternity. The reno- 

 vation of the continental surface by the great glacier, and 

 the floods which attended upon its dissolution, marked the 

 last great revolution which passed over the surface of the 

 land. Yet of all its vicissitudes, nothing has been pre- 

 served to us by the history or traditions of our race. It 

 lies back in the unmeasured realm of the geologic aeons. 

 Since the disappearance of the glacier, geological results 

 which, to the eye of a generation, seem stationary, have 

 been accumulated in aggregates of stupendous magnitude. 

 The gorge of Niagara, seven miles long, one thousand feet 

 broad, and two hundred and fifty feet deep, is thought by 

 some geologists to have been worn out by an agency which, 



