MATTER AND FORCE 63 



as a boy twirls round his head a bullet at the end of a 

 string. But why should the chain be needed? It is 

 a fact of experience that bodies can attract each other 

 at a distance, without the intervention of any chain. 

 Why should not the sun and earth so attract each 

 other? and why should not the fall of bodies from a 

 height be the result of their attraction by the earth? 

 Here then we reach one of those higher speculations 

 which grow out of the fruitful soil of observation. 

 Having started with the savage, and his sensations of 

 muscular force, we pass on to the observation of force 

 exerted between a magnet and rubbed amber and the 

 bodies which they attract, rising, by an unbroken growth 

 of ideas, to a conception of the force by which sun and 

 planets are held together. 



This idea of attraction between sun and planets had 

 become familiar in the time of Newton. He set himself 

 to examine the attraction; and here, as elsewhere, #e 

 find the speculative mind falling back for its materials 

 upon experience. It had been observed, in the case of 

 magnetic and electric bodies, that the nearer they were 

 brought together the stronger was the force exerted be- 

 tween them; while, by increasing the distance, the force 

 diminished until it became insensible. Hence the infer- 

 ence that the assumed pull between the earth and the 

 sun would be influenced by their distance asunder. 

 Guesses had been made as to the exact manner in 

 which the force varied with the distance; but Newton 

 supplemented the guess by the severe test of experiment 

 and calculation. Comparing the pull of the earth upon 

 a body close to its surface, with its pull upon the moon, 

 240,000 miles away, Newton rigidly established the law 



