Since the publication of the article MINERALOGY, Encycl., scarcely a single day has passed without the discovery of some new mineralogical fact, or the detection of some old and unsuspected error. These improvements cannot be overlooked in the present Supplement. But they are so numerous in every part of the science, that we can hardly notice them without giving a pretty complete view of the present state of mineralogy. This will scarcely occupy more room, and must be much more useful as well as entertaining, than an undigested mass of annotations and remarks. We undertake this task the more readily, because in the article MINERALOGY in the Encyclopedia, the improvements of Mr Werner and his disciples, to which the science is indebted for a great part of its present accuracy, have been entirely overlooked.

The object of mineralogy is twofold. 1. To describe every mineral with so much accuracy and precision, that it may be easily distinguished from every other mineral; 2. To arrange them into a system in such a manner that every mineral may be easily referred to its proper place, and that a person may be able, merely by the help of the system, to discover the name of any mineral whatever. When these two objects are accomplished, mi-

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