S86 Professor Mohs’ Reply to Professor Weiss, 
I have never introduced or received divisions within the systems 
of crystallization, and never can acknowledge as such those of 
M. Weiss, since they are quite contradictory to my conceptions 
of the systems of crystallization. It might, however, in future, 
become necessary to adopt new Systems of crystallization, which 
are indicated by the inclination of the axis, a highly remarkable 
phenomenon noticed in several forms of the prismatic system in 
the first outline of my Treatise. The pursuit of this phenome- 
non will probably lead to new fundamental forms , of which 
new systems of cry stallization are the necessary consequence. I 
have not yet fully developed the theory of these forms ; it would 
therefore be premature to say more on the subject : it is, how- 
ever, exceedingly probable that the properties of the axes of 
double refraction will be found exactly to correspond with these 
new fundamental forms, in the same manner as Dr Brewster 
has found them to be connected with what had previously been 
known of the crystalline forms. 
Lastly, I have to add a few remarks regarding some other 
particular points in M. Weiss’s letter, that I may not, at ano- 
ther time, be under the necessity of returning to these and si- 
milar matters. 
M. Weiss strongly objects to my denominations of the sys- 
tems of crystallization, and to my crystallographic signs. Both 
of them, as I have stated above, rest upon the series. The de- 
nominations, moreover, must possess such properties as may 
render them applicable and useful in the miner alogieal nomen- 
clature, for the sake of which they have been introduced ; and, 
among these properties, besides precision in their meaning, bre- 
vity in expression is one of the most desirable. Professor Weiss’s 
denominations being very defective, at least in the latter respect, 
do not allow of any application to the mineralogicai nomencla- 
ture ; and mine, therefore, even if we should dispense with 
other reasons, deserve, in this respect, a decided preference. 
My crystallographic designation represents either the funda- 
mental, or that form which is obtained from it by means of de- 
rivation, in the different places of the series of homogeneous 
forms contained in the series of crystallization ; which, in my 
opinion, is the most important relation among these forms that 
deserves to be expressed in the designation. Thus it expresses 
the form itself and besides this, its con?iection with all other 
