334 
SECOND REDORT- 1832. 
Instead of requiring the trigonometrical and algebraical calcu¬ 
lations of Haiiy, the law can, in a great majority of cases, be 
inferred from properties which are obvious to the eye, especially 
from the parallelisms of the edges of the faces. This mode of 
reasoning, introduced by Mohs, has been very successfully 
cultivated by succeeding writers, and especially by Naumann. 
The fertility and convenience of this resource is greater than 
any one not acquainted with it can easily imagine. With a 
collection of diagrams representing the binary combinations of 
forms, such as Naumann and others have given, the crystallo- 
metrical analysis of a very complex crystal becomes compara¬ 
tively easy. 
Still, to determine the laws of all the faces which commonly 
occur in the known species of minerals, is a task which has 
necessarily required the labour and skill of many persons. The 
early labourers in this province have a particular claim to our 
gratitude. Haiiy did much, but he left also much to do. Weiss 
(.Berlin Trans.) first successfully discussed some of the more diffi¬ 
cult and complex cases, as gypsum, felspar, epidote. Professor 
Mohs’ Treatise contains a vast treasure of such determinations, 
and has only left for more recent crystallometers the task of 
supplying special deficiencies. And of such contributions we 
have excellent examples in recent times, among which we may 
mention the examination of the crystallization of felspar by Hes- 
sel, and of the blue carbonate of copper by Zippe of Prague. 
In speaking of crystallometry, it is necessary to say something 
of notation , a subject which is repulsive to many in consequence 
of the multiplicity and complexity of the symbols which have 
been promulgated, and which is yet absolutely indispensable 
to the mineralogist who would economize time, labour, and 
thought. Perhaps it may be found that the discrepancies of 
different authors are not so great as they at first sight appear. 
The notation of Haiiy, indeed, belongs to so imperfect a know¬ 
ledge of the subject, contains so much that is arbitrary, and 
is so incapable of being rendered either simple or symme¬ 
trical, that its reign ought by this time to have become only 
a matter of history, although in fact, among the disputes of 
its successors, it retains here and there some little show of 
authority. But the systems of notation of Weiss, Mohs, and 
Naumann, have better claims to our notice. That of W eiss 
is simple, according to his view of the subject, which, it will 
be recollected, consists in using the equations to the planes 
of the crystal; his symbol for any plane consists merely of 
the three coefficients of the equation, included in brackets. Of 
this method, the main defect is, that it is too general, and does 
not very obviously exhibit those relations of the forms and 
