It is unnecessary to follow our author, while he states the principles of his sexual system of minerals, through the forms and modifications of crystals, metals, rocks, and petrifactions. His scheme of geology may be described as follows:--The strata of the earth are generally parallel to each other, although not always so, nor always of marine origin. The lowest is of sandstone (_cos_), the second of slate, the third of marble filled with marine petrifactions, the fourth of slate, the uppermost of the saxose kind, which includes granite, porphyry, trap, conglomerate, and puddingstone. It is obvious that the ocean has produced the land. It is rendered turbid by nitrous showers, precipitates, and is crystallized into sand, which covers the bottom of the sea. The surface of it is here and there covered over to a great extent with floating fuci, the mould derived from which gradually descends, while the lighter particles help to form a floating meadow. Marine vermes, the mollusca, testacea, lithophytes, and zoophytes, together with fishes and sea-birds, feed beneath this floating meadow. An argillaceous sediment falls down in the quiet water, and this, together with the calcareous shells of the marine vermes, gradually forms a heap, which rises to the surface, while the pressure agitating the water drives out the marine animals. On the rock thus formed, the sea casts up great quantities of fuci, which are converted into mould, until at length the sandy earth rises above the surface, dries, is driven about, and concresces into gravel and sandstone. In the course of ages, the sand is hardened into sandstone, the mould into bituminous shale and coal, the clay into marble, other layers of mould into other beds of shale or slate, and other masses of sand into gravel and conglomerate. This again is converted into pebbles, these into stones, the stones into rocks. At length, the water subsiding, the mass becomes a mountain. Had Linnaeus been as unfortunate in his other theories as in this, his name would have been long ago forgotten. However fanciful his theoretical views may be, his classification is not unworthy of praise, and his specific definitions are generally intelligible to a modern mineralogist; but this is nearly all, however, that can be said in their favour. He divides the mineral kingdom into three classes, under the names of _Petrae_, _Minerae_, and _Fossilia_. These are again subdivided into several orders, and the number of genera amounts to fifty-four. Class I. PETRAE or STONES, or, as modern geologists would say, ROCKS. Steril stones, originating from an earthy principle by cohesion; simple, as being destitute of salt, sulphur, or mercury; fixed, as not being intimately soluble; similar, as consisting of particles united at random. Order I. HUMOSAE. Deposited from vegetable earth, combustible and burning to cinders, their powder harsh and light; as roofing-slate.