in regard to Discoveries in Crystallography. £85 
The description of the simple forms of all the systems, with the 
same words as in the treatise, only sometimes more detailed ; 
together with the indication of the dimensions relative to the 
known varieties of the tessular forms. There is also men- 
tioned the difference of the pentagonal icositetrahedrons, and 
of the tetrahedral pentagonal dodecahedrons, according to right 
and left, which certainly could not be deduced from M. Weiss’s 
paper on Felspar, in the Journal of Schweigger ; because in 
this, as far as I remember, the author extends his consideration 
only to compound minerals, in the composition of which the in- 
dividuals themselves are not in the relation of right and left. 
5 dly, The general method, and the different proceedings of de- 
rivation, with the series of the homogeneous simple forms arising 
from them. 4 thly, The complete resolution of the seven princi- 
pal forms of the tessular system, their halves and fourths. 5tJily y 
The general notions of the series and of the systems of crystalli- 
zation, the latter of which I have always defined to be the As- 
semblage of Homogeneous Series of Crystallization. 6thly , The 
general laws of combination ; and, 7 thly, Several examples of 
their development. 
Of these combinations one is dirhombohedral ; two are hemi- 
prismatic ; four semitessular ; and among these three of parallel, 
and one of inclined faces. I had not, indeed, at that time made 
use of these denominations, which I afterwards introduced ; and 
to which, besides, Professor Weiss does not raise any claims. 
But I have constantly expressed the same crystallographic signs 
which I still retain. 
For the truth of this I appeal to you and to Count Breunner, 
who is as intimately acquainted with the manuscript as yourself. I 
may add Captain Pringle, one of your pupils, who accompanied 
me on my return to Germany, and who studied it very diligently 
during his stay at Frey berg. If you read Professor Weiss’s 
paper, you will not, after the perusal of my manuscript, find 
any thing new in it. But you will in vain search for what I 
consider to be the most important part of the manuscript ; and, 
therefore, even though I should incur the risk of lengthening 
too much this defence, I shall still, for a moment, trespass upon 
your patience. 
