stone, in the Tyrolese, might perhaps be explained in this manner, and we are at least certain that the cause exists. But it is far from the intention of this work to propose or support any theory; and these remarks must only be regarded as a few scattered hints which may interest the reader.

Pini, in what he calls a new theory of the earth, supposes Pini's system. a nucleus surrounded with a fluid zone, which contained the elements of the various substances; and he imagines the effects and variations to have been very prompt and sudden, owing to the extreme rapidity of the rotation of the earth. He argues for a formation wholly aqueous; but his chief new fact seems to be a granitic mountain at Gana, in Austrian Lombardy, which is throughout full of cavities, a few inches distant from each other, and lined with crystals of quartz and felspar *.

The chief features of De Luc's new system of geology De Luc's. seem to be the following. He supposes that during the deluge the former continents disappeared; but this is clearly contrary to the Mosaic account of paradise, and the whole scriptural narrative, which represents the land as stable and unalterable. That successive catastrophes affected the beds of our continents, even while they were rising under the waters by chemical precipitations, being occasioned by caverns which formed under them. That valleys, lakes, abrupt precipices, existed at the birth of our continents, in consequence of those catastrophes by which the beds were ruined. That stony masses and gravel, which are scattered in such great quantities upon the continents, are also original features, and do not arise from currents; the flints proceeding from beds of chalk dissolved; and the gravel, as well as the large blocks, caused by the attrition of fragments, have been expelled from the interior by expansive fluids, during the subsidence of the beds, and dispersed at the same time at the bottom of the sea. That the precipices towards the sea have not been produced by the sea itself, but are original features,

See the Opuscoli Scelti, tom. xiii. Milan 1790, 4to. p. 369, 379.

resulting from the rupture of the beds, at the time of the vast subsidence which sunk the former continents, and produced the new concavity of the ocean.

These theories may be compared with the Wernerian and Huttonian, and that of Ferrara, founded, as he says, on that of Burnet. The rocks having been hitherto considered as the chief province of the geologist, it is hoped these few cursory remarks will not be found foreign to the purpose. But Petralogy, as already observed, has little more connexion with Geology than its sister sciences Lithology or Metallogy; and, like them, can only be regarded as an introduction. In which point of view these observations may not be found unuseful to the student. But it is time to return to the description of the Accidential Domains, an accurate knowledge of which may be regarded as peculiarly indispensable to any system of geology, such theories having so often confounded the pride of human science. The more humble sage will perhaps be contented with the knowledge of the substances themselves, and prefer what Gibbon calls a LEARNED IGNORANCE to any geological theory.