the Population Returns of Plymouth for 1821. 275 
ciple, and which in its consequences leads to results of the high- 
est importance and value to man. This is not, however, the 
proper place to insist particularly on the advantages which 
have resulted to the various branches of physical science, from 
the application of mathematical symbols and signs,-— from their 
definite phraseology, — from the fixed and unchangeable rela- 
tions which form the proper objects of the science, and which so 
often imparts its own precision to those branches of knowledge 
to which it is applied, although, to have omitted alluding to the 
subject, would have been improper, after the striking coinci- 
dences which have been above obtained. 
Art. VIII. — On the Crystallographic Discoveries and Systems 
of Mohs and IFeiss. In a Letter from Frederick Mohs, 
Esq. Professor of Mineralogy at Freyberg, to Professor 
Jameson, in Answer to that of Professor Weiss, in the last 
Number of this Journal. (Page 103, &c.) 
Sir, 
I find it necessary to communicate to you a few observations, 
that have offered themselves to me, on reading the letter from 
Prof. Weiss, inserted in Number 15. of the Edinburgh Philoso- 
phical Journal, which you had the kindness to transmit to me. 
In this letter M. Weiss accuses me of having borrowed from 
him without acknowledgment, and claims at the same time for 
himself the establishment of the systems of crystallization, under 
which I have assembled the regular forms produced by nature. 
He considers himself as the original source of all information on 
this subject, and seems to intimate in his letter, that he has ra- 
ther invented than abstracted those systems from nature. I be- 
lieve, therefore, I must begin my communications respecting 
them, with stating the manner in which I have been led by de- 
grees to their development. 
You know that, from the time I first became acquainted with 
minerals and mineralogy, I entertained the opinion that this 
science should form a part of Natural History , and as such be 
treated according to the principles received in Zoology and 
Botany. This at least will occur to your memory, if you reflect 
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