deposited during a single shower, for beds of rich earth, each of which would have taken centuries to form. The oldest of the series of lava beds, therefore, instead of being fourteen thousand, might be scarce fourteen hundred years old. And if Brydone or the Canon were thus mistaken in their calculations, why may not the modern geologists be also mistaken in theirs? Now, altogether waiving the question as to whether the ingenious traveller of eighty-six years ago was or was not mistaken in his estimate,--for to those acquainted with geologic fact in general, or more particularly with the elaborate descriptions of Ætna given during the last thirty years by Elie de Beaumont, Hoffmann, and Sir Charles Lyell, the facts of Brydone, in their bearing on either the age of the earth or the age of the mountain, can well be spared,--waiving, I say, the question whether the traveller was in reality in mistake, I must be permitted to remark, that the concurrent testimony of geologists cannot in fairness be placed on the same level as the testimony of a man who, though accomplished and intelligent, was not only no geologist, but who observed and described ere geology had any existence as a science. Further, I must be allowed to add, that geology _is_ now a science; and that individuals unacquainted with it in its character as such place themselves in positions greatly more perilous than they seem to think, when they enter on the field of argument with men who for many years have made it a subject of special study. It is not by "bidding down" the age of the extinct or quiescent volcanoes by a species of blind haggling, or by presuming mistake in the calculations regarding them, simply because mistakes are possible and have sometimes been made, that that portion of the cumulative evidence against a universal deluge which they furnish is to be neutralized or set aside. The argument on the general question _is_ a cumulative one; and while many of its component portions are of themselves so conclusive, that only supposititious miracle, and not presentable argument, can be arrayed against them, its aggregate force seems wholly irresistible. In passing, however, from the facts and reasonings that bear against the hypothesis of a universal deluge, to indicate in a few sentences both the possible mode in which a merely partial flood might have taken place, and the probable extent of area which it covered, I shall have to remove from very strong to comparatively weak ground,--from what can be maintained as argument, to what can at best be but offered as conjecture.