THAW. 73 



have not only rent the vegetables to pieces, but 

 resolved the rocks themselves into dust. Then in the 

 high latitudes, where the temperature is below 32 for 

 some months, and the snow of the uplands and moun- 

 tains many fathoms in depth, the first rise of tempera- 

 ture would have brought down the whole in one 

 overwhelming flood, to which the most violent that 

 now happens would not have been more than a summer 

 dew in comparison. A fall of rain, equal to a depth 

 of five or six inches, happening in the course of an 

 entire day, instead of instantaneously, is found suffi- 

 cient to sweep the produce and soil from the surface 

 of those countries that have the misfortune to be visited 

 by it ; but there are places where the snow would, if 

 immediately melted, produce nearly, as many feet 

 of water, and were that to be set loose at once, every 

 substance under some tons in weight would be washed 

 to the sea, and the ruin would be complete and with- 

 out remedy. Such are the evils which are prevented 

 by the great heat necessary to melt ice, and the conse- 

 quent slowness with which it is converted into a liquid. 

 That ice should melt with a few degrees less or more 

 of heat, would appear to those who are not in the habit 

 of looking beyond the mere surface of things, as a 

 matter of very little consequence, and it did so appear 

 for the greater part of the past history of the world, 

 both to the unlearned and the learned ; and yet were 

 it not for that apparently trivial circumstance, a large 

 portion of the earth's surface would be useless. 



But there is the production of good, as well as the 

 prevention of evil, arising out of this accumulation of 

 energy (so to speak) that is necessary for changing the 



