S4J2 Mohs' System (^Crystallography and Mineralogy. 
are more conformable to custom than systematic ones, and as 
are fitted, so to speak, for familiar use, the properties of the ob- 
ject being exhibited, or at least not obscured by its designation. 
Beyond this, however, entirely to relinquish systematic names, as 
it abstracts from science a powerful help to its easier extension, 
must be a very censurable mode of proceeding. 
20. The Trivial Name depends on the Species. — By using 
the trivial nomenclature, not only our knowledge 6f the object, 
but also of the connection in which it stands with others, is ex- 
pressed. The trivial name is hence never applied to an order 
or a genus ; and upon this circumstance is founded the conve- 
nience of employing such names, which on that account can ne- 
ver be compounded. Neither trivial nor systematic names ought 
to reach lower than the species, which it does not seem (11.31.) 
advantageous to divide. 
21. Properties of a Trivial Name. — The first, the essential, 
but also the only property of a trivial name, here to be consi- 
dered, requires it therefore to consist of a single word. Of this 
kind are spinel for octahedral corundum ; euclase for prismatic 
emerald ; rutile for prismato-pyramidal titanium-ore, forming 
very suitable designations. But what are we to think of com- 
pound trivial names ? Whoever uses them, imposes on himself, 
without necessity or advantage, a burden which it is the sole in- 
tention of a trivial nomenclature to remove. 
22. Compound Trivial Names are to he rejected. — A com- 
pound trivial name assumes the appearance of a systematic de- 
nomination. Whenever, therefore, such a name is not deduced 
from a system, or even not from that system, in which it is em- 
ployed, it can serve for nothing but to embroil those concep- 
tions which it is the main object of the whole science to unravel. 
It costs labour to forget the notion that hornblend, coal-blend, 
are species of hlend ; and when in one genus we meet with such 
names as native copper, copper-glass, variegated copper-ore, 
azure copper, copper-green, and so forth, in that case, the best 
thing we can do is to veil the mirror, that no botanist or zoolo- 
gist, at least, may observe the image traced within. 
( To he concluded in next Number. ) 
