[ xviii ] 



the reft are compounded, although this cannot 

 yet be perfectly proved to a demonftration. 



The Lufi Nalurce are not leparately treated 

 herein ; they may be found every where in the 

 EfTay, becaufe the rock cryftals do not appear 

 to me lefs curious than the indurated marles ; 

 and the kidney ore is often found of a more 

 furpriflng figure than the eagle-ftone. I can- 

 not therefore find any reafon for forming a 

 clafs of them, nor do I comprehend what 

 others take to be a greater or lefs iport of na«* 

 ture in the mineral kingdom. 



Figured flones, or which contain the r.epre-* 

 fentations of vegetables, animals, &c. occafion-? 

 ed by different veins or colours in the flones, 

 are in my opinion of ftill lefs confequence, and 

 are alfo mere difficult to range properly in 

 blafles ; becaufe people feldom, or rather never, 

 agree in their fancies ; but what feems to re T 

 prefent an object to one, may make a different 

 appearance in the imagination of another, 

 whereby both confufion and difputes would 

 arife about the bodies of fuch a clafs. Befides., 

 a very fmall advantage, if any, can refult from 

 fuch a clafs ; fince all that the Almighty 

 created has required equally his power, and is 

 alfo equally worthy of our admiration : It gives 

 rather rife to pedantry, whereby the attention 

 is by degrees diverted from true knowledge to 

 mere trifles, of which both ancient and mo- 

 dern books are fad inftances -, and if Mr. Du 

 Fay had not impeded the evil by difcovering the 

 method of improving the figures upon flint 



