upon a floor) to be raised at one edge, 

 and then suddenly brought down again 

 to the floor ; the air under it, being by 

 this means propelled, will pass along, till 

 it escapes at the opposite side, raising the 

 cloth in a wave all the way as it goes. 

 In like manner, a large quantity of vapour 

 may be conceived to raise the earth in 

 a wave, as it passes along between the 

 strata, which it may easily separate in 

 an horizontal direction, there being, as 

 I have said before, little or no cohesion 

 between one stratum and another. The 

 part of the earth that is first raised, being 

 bent from its natural form, will en- 

 deavour to restore itself by its elasticity, 

 and the parts next to it, beginning to 

 have their weight supported by the 

 vapour, which will insinuate itself under 

 them, will be raised in their turn, till it 

 either finds some vent, or is again con- 

 densed by the cold into water, and by 

 that means prevented from going any 

 further" (Art. 58). 



3' 



