ATTRACTION Of GRAVITATION. 31 



attraction of cohesion. The latter is not perceptible but in 

 very minute particles, and at very small distances, the other 

 acts on the largest bodies, and extends to immense distances. 



That very law which moulds a tear, 



And bids it trickle from its source, 



That law preserves the earth a sphere. 



And guides the planets in their course. — Rogers. 



The tendency which bodies have to fall is produced en- 

 tirely by the attraction of the earth ; for the earth is so much 

 larger than any body, on its surface, that it forces every 

 body, which is not supported, to fall upon it. The follov/ing 

 simple incident led to the most extensive and complicated 

 calculations, and was productive of the most noble and won- 

 derful discoveries. Newton happening one day, in the year 

 1666, when only twenty-five years of age, to be sitting under 

 an apple-tree, and an apple falling upon his head, it suggested 

 a variety of reflections. The phenomena of falling bodies 

 in particular engaged his attention ; and, extending his re- 

 searches to the heavens, he began to investigate the nature 

 of motion in general. Because there is motion, he reason^ 

 ed, there must be a force that produces it. But what is this 

 force 1 That a body when left to itself, will fall to the ground, 

 is known to the most ignorant ; but if you ask them the rea- 

 son of its thus falling, they will think you either an idiot or ' 

 a madman. The circumstance is too common to excite their 

 wonder, although it is so embarrassing to philosophers, that 

 they think it almost inexplicable. It is the mark of a supe- 

 rior genius to find matter for wonder, observation, and re- 

 search, in circumstances which to the ordinary mind appear 

 trivial, because they are common, and with which they are 

 satisfied, because they are natural, without reflecting that 

 nature is our grand field of observation, that within it is con- 

 tained our whole store of knowledge ; in a word, that Us 

 study the works of nature, is to learn to appreciate and ad- 

 mire the wisdom of God. 



In applying his reflections on the nature of falling bodies 

 to the celestial motions, Newton soon perceived that the 

 force of gravity was not confined to the surface of our globe ; 

 it being found to act alike at the bottom of the lowest valleys, 

 jind at the summit of the most lofty mountains. This led 



