$78 Professor Mohs’ Reply to Professor Weiss, 
you know, the Rhombohedral, the Pyramidal , the Prismatic , 
and the Tessular System . 
Here I must request you to direct your attention more parti- 
cularly to two points. I have to observe, in the first place, that 
my systems of crystallizations are founded upon very simple ob- 
servations, and upon such inferences from them as may be de- 
duced with the greatest facility. I have always explained in the 
same manner as I do now, the three notions developed above, viz. 
that of a System of Crystallization, that of a Series of Crystalli- 
zation, and that of a Series of Homogeneous Forms , which are 
subordinate to each other ; but of which, at least the first and 
second have been almost continually confounded by most authors, 
whose conceptions of them have not been sufficiently clear. My 
second remark is, that, by establishing these systems and series 
of crystallization, I had entirely fulfilled my intention , which 
was to obtain characters ; a subject with which you are suffi- 
ciently acquainted, by the mode in which it has been per- 
formed. 
This is the quality and the origin of what I have designated 
by the words System of Crystallization ; and these systems, both 
in quality and origin, are different from what other crystallo- 
graphers, and more particularly the Abbe Haiiy and Professor 
Weiss, mean by the same denomination. I have likewise point- 
ed out the way by which I have gradually been led to the de- 
velopment of these notions. 
I must not neglect the opportunity afforded me here, of men- 
tioning the assistance which I have received from my friend 
M. W. Haidinger, in the development of the series, the calcu- 
lations, measurement, &c.y to which I attribute the rapid pro- 
gress of my crystallographic method. M. Haidinger enjoys the 
honour of your personal acquaintance, and before now I have 
mentioned the circumstance more than once to you ; yet I have 
thought it necessary to repeat it here, that I may not seem to 
consider myself guilty of the fault which M. Weiss has laid to 
my charge. 
I was occupied with the different crystallographic subjects of 
which I have just now given the historical details, during the 
years 1812,-14, in the autumn and winter of the last of which, 
I for the first time brought the whole of it into systematic or- 
