58 FKAGMENTS OF SCIENCE. 



fall of bodies from a height be the result of their at- 

 traction by the earth? Here then we reach one of 

 those higher speculations which grow out of the fruit- 

 ful soil of observation. Having started with the sav- 

 age, 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 to- 

 gether. 



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 else- 

 where, we 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 between them; while, by increasing 

 the distance, the force diminished until it became in- 

 sensible. Hence the inference 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 of variation with 

 the distance. But on his way to this result Newton 

 found room for other conceptions, some of which, 

 indeed, constituted the necessary stepping-stones to his 

 result. The one which here concerns us is, that not 

 only does the sun attract the earth, and the earth at- 

 tract the sun, as wholes, but every particle of the sun 

 attracts every particle of the earth, and the reverse. 



