298 THEORY of the EARtH. 



compofition of a future earth. Let us, therefore, now attempt 

 to make this eftimate of time and labour. 



THE higheft mountain may be levelled with the plain from 

 whence it fprings, without the lofs of real territory in the 

 land ; but when the ocean makes encroachment on the ban's of 

 our earth, the mountain, unfupported, tumbles with its weight j 

 and with that acceffion of hard bodies, moveable with the agi- 

 tation of the waves, gives to the fea the power of undermining 

 farther and farther into the folid bans of our land. This is 

 the 'operation which is to be meafured ; this is the mean pro- 

 portional by which we are to eftimate the age of worlds that 

 have terminated, and the duration of thofe that are but begin- 

 ning. 



BUT how (hall we meafure the decreafe of our land ? Every 

 revolution of the globe wears away fome part of fome rock 

 upon fome coafb ; but the quantity of that decreafe, in that 

 meafured time, is not a meafurable thing. Inftead of a revo- 

 lution of the globe, let us take an age. The age of man does 

 no more in this eftimate than a fingle year. He fees, that the 

 natural courfe of things is to wear away the coaft, with the at- 

 trition of the fand and ftones upon the more ; but he cannot 

 find a meafure for this quantity which mall correfpond to time, 

 in order to form an eftimate of the rate of this decreafe. 



BUT man is not confined to what he fees ; he has the expe- 

 rience of former men. Let us then go to the Romans and the 

 Greeks in fearch of a meafure of our coafts, which we may 

 compare with the prefent ftate of things. Here, again, we are 

 difappointed ; their defcriptions of the mores of Greece and of 

 Italy, and their works upon the coaft, either give no meafure 

 of a decreafe, or are not accurate enough for fuch a purpofe. 



IT is in vain to attempt to meafure a quantity which efcapes 

 our notice, and which hiftory cannot afcertain ; and we might 

 juft as well attempt to meafure the diftance of the ftars with- 

 out 



