6 GRAVITATION. 



of nature are governed. There is an illustration 

 of another kind of power in that lamp ; there is 

 a power of heat a power of doing something, 

 but not the same power as that which pulled 

 the paper over : and so, by degrees, we find 

 that there are certain other powers (not many) 

 in the various bodies around us.; and thus, 

 beginning with the simplest experiments of 

 pushing and pulling, I shall gradually proceed 

 to distinguish these powers one from the other, 

 and compare the way in which they combine 

 together. This world upon which we stand 

 (and we have not much need to travel out of 

 the world for illustrations of our subject; but 

 the mind of man is not confined like the 

 matter of his body, and thus he may and does 

 travel outwards, for wherever his sight can 

 pierce, there his observations can penetrate) is 

 pretty nearly a round globe, having its surface 

 disposed in a manner of which this terrestrial 

 globe by my side is a rough model ; so much is 

 land and so much is water, and by looking at it 

 here we see in a sort of map or picture how the 

 world is formed upon its surface. Then, when 

 we come to examine further, I refer you to this 

 sectional diagram of the geological strata of the 



