54 CECONOMY 



and therefore it is a vulgar miflake, that our 

 anceicors excelled the modern architects in the 

 art of building as to this point ^. 



However ignorant we niay be of the caufe, 

 why large rocks are every where to be feen 

 fplit, whence vafl fragments are frequently torn 

 off; yet this we may obferve, that fifliires are 

 clofed up by water, that gets between them, 

 and is detained there i and are confolidated by 

 cryftal and fpar. Hence we fcarcely ever find 

 cryfial^ but in thofe jicms^ which have for fome 

 time in its chinks water loaded with ftony par- 

 ticles. In the fame manner cryftals fill the ca- 

 vities in mines, and concrete into quartz or a 

 debafed cryftal. 



It is manifefl x}[V3Xftoyies are not only gene^ 

 rated, augmented, and changed perpetually 



^ Too great ftrefs ought not, I think, to be laid on this 

 obfervation of our author, though it may be in part true ; 

 for without fuppofing that our anceilors had more fkill in 

 building, we may fuppofe, what was likely to be the cafe, 

 that they ufed more care in the choice of their materials, 

 and had them wrought up with more labor; which mull 

 add confiderably to the firmnefs of the cement. Where thefe 

 circumflances have happened to be wanting, time alone has 

 not been able to produce the fame eiFed. I have feen a 

 houfe about fourfcore years old, where one might rub out 

 the mortar from between the bricks without fcarcely ufing 

 any force. 



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