392 Theory of Cryjlallifation. 



decreafe, in departing from this nucleus, exifted already in 



the riling cryftal. 



The theory I have explained, fimilar in this to other 

 theories, fets out from a principal fa&, on which it makes 

 all facts of the fame kind to depend, and which are only as 

 it were corollaries. This fa£t is the decrement of the laminae 

 fuperadded to the primitive form; and it is by bringing, 

 back this decrement to finlple and regular laws, fufceptible 

 of accurate calculation, that theory arrives at refults the 

 truth of which is proved by the mechanical divifion of 

 cryftals, and by observation of their angles. But there ftill 

 remain new refearches to be made, in order to afcend a few 

 fteps farther towards the primitive laws to which the Creator 

 has fubje&ed cryitallifation ; and which are nothing elfe 

 themfelves than the immediate effects of his fupreme will. 

 The object of one of thefe refearches would be to explain 

 how thefe fmall polyedra, which are, as it were, the rudi- 

 ments of cryftals of a ienfible bulk, reprefent fometimes the 

 primitive form, without any modification ; fometimes a 

 fecondary form produced in virtue of a law of decrement ; 

 and to determine the circumftances which produce decre- 

 ments on the edges, and thofe which give rife to decrements 

 on the angles. I have already paid attention to the folution 

 of this problem, as delicate as it is interefting ; but hitherto 

 I have only had conjectures, which, before they deferve to 

 be publifhed, require to be verified by more attentive labour 

 and more profound meditation. 



JX. On 



