the Corundum Stone, and its Varieties, &c. 239 
to be placed; but the progress by which we have arrived at this 
degree of knowledge was necessarily very slow, and was im- 
peded by continual obstacles : for the scarcity and smallness of 
the crystals of corundum, and the impression naturally made 
upon our minds by the various appearances it exhibited to us, 
were by no means likely to lead us to form a true judgment 
respecting it. So that Mr .Werner, whose great and acknow- 
ledged talents have justly caused his opinion to be considered, 
nearly throughout all Germany, as of the highest importance 
in all mineralogical decisions, has hitherto continued to place 
corundum between pitchstone and felspar; consequently, he 
has removed it to a considerable distance from the sapphire, 
since there exists, according to his classification, nearly thirty 
intermediate substances. 
Crystallography also offers some difficulties with respect to 
this stone ; and these difficulties are only to be guarded against 
by a very particular study of it, and especially by an accurate 
examination of all its varieties, as objects of comparison. 
The Abbe Hauy, to whose great knowledge of crystallo- 
graphy all Europe is eager to do justice, although he gave 
some indications that he began to waver in his opinion, did 
not think there were reasons sufficiently strong to adopt that 
which I had, without satisfactory evidence, advanced in 1798; 
and has continued to separate the corundum from the sap- 
phire, giving to the latter the name of Telesie . In the new 
System of Mineralogy, which the Abbe Hauy has just pub- 
lished, he places corundum immediately after felspar, and before 
ceylonite, the name of which he has changed into Pleonaste. 
One cannot help being astonished that the very great hardness 
, of this stone, as well as its great gravity, did not lead him to 
I i 2 
