He says, "a mole having been constructed in the Oder in the year 1723, 350 feet long, 54 feet in height, 144 feet broad at bottom, and 54 at the top, its sides only were granite, without any other cement than moss; the middle space was entirely filled with granite sand. In a short time this concreted into a substance so compact as to be impenetrable by water."--Here is an example, according to our author, of _granite formed in the moist way_. But now, I must ask to see the evidence of that fact; for, from what our author has told us, I do not even see reason to conclude that there was the least concretion, or any stone formed at all. A body of sand will be _so compacted as to be impenetrable by water_, with the introduction of a very little mud, and without any degree of concretion; muddy water, indeed, cannot be made to pass through such a body without compacting it so; and this every body finds, to their cost, who have attempted to make a filter of that kind. But I shall suppose Lasius has informed our author that there had been a petrifaction in this case; and, before I admit this example of the formation of granite, I must ask what sort of a granite it was;--whether of two, three, or four ingredients; and, how these were disposed. If, again, it were not properly a granite, but a stone formed of granite sand, What is the cementing substance?--Is it quartz, felt-spar, mica, or schorl?--or, Was it calcareous? If our author knows any thing about these necessary questions, Why has he not informed us, as minutely as he has done with regard to the dimensions of the mole, with which we certainly are less concerned? If, again, he knows no more about the matter than what he has informed us of, he must have strangely imposed upon himself, to suppose that he was giving us an example of the _formation of granite in the moist way_, when he has only described an effectual way of retaining water, by means of sand and mud. CHAP. III. Of Physical Systems, and Geological Theories, in general. In the first chapter I have given a general theory of the earth, with such proofs as I thought were sufficient for the information of intelligent men, who might satisfy themselves by examining the facts on which the reasoning in that theory had been founded. In the second chapter, I have endeavoured to remove the objections which have been made to that theory, by a strenuous patron of the commonly received opinion of mineralogists and geologists,--an opinion which, if not diametrically opposite, differs essentially from mine. But now I am to examine nature more particularly, in order to compare those different opinions with the actual state of things, on which every physical theory must be founded. Therefore, the opinions of other geologists should be clearly stated, that so a fair comparison may be made of theories which are to represent the system of this earth.