Theories of the Tides. 221 



Now if the waters between B and C, in consequence of their 

 superior gravity, fell down to the dotted hne Br, there would 

 necessarily be a corresponding rise on the opposite side of B 



1 T 



to make room lor this depression; but, as the area «cEis 

 eqrial * to the area A C E, it is evident that this rise would not 

 thefeH C r ""* the dotted line A a, which is just equal to 



Now, Sir, if you meant to be understood that the waters 

 are dravvn up simply by the power of the moon's attraction, 

 you are bound to show how it happens that the moon's attrac- 

 tion has power to lift the waters up, when it has not power to 

 prevent them from foiling : if you meant that the waters are 

 litted up by the expansion of their own particles, you ought in 

 justice, to have admitted my theory to be true; and if vou 

 meant that they are lifted up by the pressure of the hea^^ier 

 particles, independent of expansion, your principle will not ac- 

 count for the elevation being greater than the fall; and I be<r 

 you to keep this latter foct in mind, because I shall presently 

 make use of it as an argument to prove the superiority of mv 

 theory over yours. "^ ^ 



But, whatever may be the princii)lc by which you account 

 for the rismgof the tides, you have plainly stated as fects, that, 

 from some cause or other, there is an elevation produced in 

 the Southern Ocean of forty inches, and a foil of twenty; that 

 this trifling elevation of only forty inches sends a wave into 

 the Atlantic, at the amazing rate of five hundred miles an hour, 

 which hnally raises the tides on our shores two or three times 

 as Ingli as the source from whence they are derived. Now 

 as water is never known to rise above its source, I cannot un- 

 derstand how a rise and fkll in one place of only five feet can 

 produce a rise and lIiU in another i)lace of sixteen or eighteen 



♦ In fact it is rather more; but as this diflferencc, in a radius of four 

 housan.l ,n.U.s w.tl. a »;.ll oConi^ a few fathoms. «„„l.l <,„ly amount to an 

 inhnitely small fraction, the two areas may be considered as essentially the 



fctl ; 



