It is requiſite, for the proper diſcrimination of foſſils, to eſtabliſh certain characters, whereby they may, at all times, and in all places, be diſtinguiſhed from one another. The ſcience that teaches theſe is called Mineralogy.
As in the vegetable kingdom different methods have been formed upon the roots, the leaves, the flowers, the fruit, &c. ſo alſo in Mineralogy many methods may be deviſed, and there is no doubt of the utility of contemplating inorganic bodies in every point of view; for the more compariſons are multiplied, the more evidently do reſemblances or differences appear.
But as the chief object of the ſcience is to render foſſils ſubſervient to the uſes of man, it is evident that that method muſt be the beſt which diſplays their component parts: for theſe being well underſtood, we know what to expect from them; we accommodate our deſigns to their nature, and ſpend not our labour and money in vain attempts inconſiſtent with their inherent qualities.
There is a power implanted by the creator in organized bodies, which, upon the acquiſition of proper nutriment, unfolds and evolves the ſtructure which before lay concealed in the fecundated egg or ſeed. Similar veſſels, in each ſpecies, abſorb, convey, and aſſimilate the nouriſhment in the ſame manner; ſo that the appearance and ſtructure remain the ſame, unleſs peculiar cauſes prevent the accuſtomed courſe of things, and produce monſters: but this very rarely happens. Hence it is that the leading features or the external parts agree with the internal properties, and when judiciouſly choſen, form ſufficient characteriſtic diſtinctions.
But the formation of foſſils is totally different. Here no ſyſtem of veſſels collects, diſtributes, ſecretes or changes the concurrent particles, but they run together by chance, and are ſolely connected by the power of attraction; they are generally, too, of different kinds, rare and denſe, figured and ſhapeleſs, admitting of every poſſible variety. This general view of the ſubject ſhews us how little external characters can be depended on; but we ſhall more particularly conſider the principal of theſe.