218 HISTORY OF 



tide ; and it is high tide at that part wherever 

 the moon comes over it, or to its meridian. 



But when the moon travels onward, and ceases 

 to point over the place where the waters were 

 just risen, the cause here of their rising ceasing 

 to operate, they will flow back, by their natural 

 gravity, into the lower parts from whence they 

 had travelled ; and this retiring of the waters will 

 form the ebbing of the sea. 



Thus the first part of the demonstration is ob- 

 vious ; since, in general, it requires no great sa- 

 gacity to conceive that the waters nearest the 

 moon are most attracted, or raised highest by the 

 moon. But the other part of the demonstration, 

 namely, how there come to be high tides at the 

 same time on the opposite side of the globe, and 

 where the waters are farthest from the moon, is 

 not so easy to conceive. To comprehend this, it 

 must be observed, that the parts of the earth and 

 its waters that are farthest from the moon, are the 

 parts of all others that are least attracted by the 

 moon : it must also be observed, that all the 

 waters, when the moon is on the opposite side of 

 the earth, must be attracted by it in the same 

 direction that the earth itself attracts them ; that 

 is, if I may so say, quite through the body of the 

 earth, towards the moon itself. This, therefore, 

 being conceived, it is plain that those waters 

 which are farthest from the moon, will have less 

 weight than those of any other part, on the same 

 side of the globe ; because the moon's attraction, 

 which conspires with the earth's attraction, is 

 there least. Now, therefore, the waters farthest 



