THE EARTH. 217 



Mankind continued for several ages content 

 with knowing the general cause of these wonders, 

 hopeless of discovering the particular manner of 

 the moon's operation. Kepler was the first who 

 conjectured that attraction was the principal 

 cause ; asserting, that the sphere of the moon's 

 operation extended to the earth, and drew up its 

 waters. The precise manner in which this is 

 done, was discovered by Newton. 



The moon has been found, like all the rest of 

 the planets, to attract, and to be attracted by the 

 earth. This attraction prevails throughout our 

 whole planetary system. The more matter there 

 is contained in any body, the more it attracts ; 

 and its influence decreases in proportion as the 

 distance, when squared, increases. This being 

 premised, let us see what must ensue upon sup-, 

 posing the moon in the meridian of any tract of 

 the sea. The surface of the water immediately 

 under the moon is nearer the moon than any 

 other part of the globe is ; and, therefore, must 

 be more subject to its attraction than the waters 

 any where else. The waters will, therefore, be 

 attracted by the moon, and rise in a heap ; whose 

 eminence will be the highest where the attraction 

 is greatest. In order to form this eminence, it is 

 obvious that the surface, as well as the depths, 

 will be agitated; and that wherever the water 

 runs from one part, succeeding waters must run 

 to fill up the space it has left. Thus the waters 

 of the sea, running from all parts, to attend the 

 motions of the moon, produce the flowing of the 



