Let us, for the illustration's sake, suppose that the British islands had been the scene of the Deluge; and that it had been occasioned by a gradual depression in the earth's surface of about fifteen hundred miles in length, a thousand miles in breadth, five thousand feet in depth in its centre, and which gradually trended all around towards the sides. Such a depression would form a scarce appreciable inequality on the surface of even a three feet globe; in a twelve inch globe it might be represented by the abrasion of a small patch of the varnish; nor would it have in nature one sixth the depth, or one sixteenth the area, of the bed of the Atlantic Ocean. Let us suppose further, that it had been produced by an equable sinking of the surface, prolonged for forty days at the rate of one hundred and twenty-five feet per day,--a motion not equal to that of the minute-hand of a clock whose dial plate measures two feet in diameter. Further, let us suppose that a thoroughly intelligent man,--let us say Dr. Kitto himself,--secure from all personal danger in an ark perched on some such commanding eminence as Arthur's Seat, had been a witness of the catastrophe; and that, instead of having merely to reason respecting it after the lapse of more than four thousand years, he had been enabled to bear testimony regarding it from the evidence of his senses. In the first place, let me remark that the sinking or downward motion of the earth's crust would be altogether inappreciable by sense; in the next, that the depression, even when it had reached its acme, would in no sensible degree affect the contour of surrounding objects. Even at the end of the forty days, when the five thousand feet of depression had been reached, the gradient of declination across the sunken area would not exceed _ten_ feet per mile, and across the larger diameter would amount to but _six feet eight inches_ per mile. Of course, at the end of the twentieth day the gradients would be represented by but one half these sums, and would be altogether inappreciable in the landscape; the hills would seem quite as high as before, and the valleys not more profound. The only sensible sign felt or visible of what was taking place would be simply a persistent rising of the sea at somewhat less than twice its rate of flow during stream tides. Ocean, as if forgetful of its ancient bounds, would continue to encroach upon the land. On the second day the greater part of what is now the site of Edinburgh would be covered; on the seventh day the tide would have reached the vessel perched on the top of the hill now known as Arthur's Seat; on the sixteenth day the highest peak of the Pentlands would have disappeared; and in nine days more the distant summit of Ben Lomond. From the roof of the slowly drifting ark nothing would then have appeared save a shoreless ocean. But it would have taken yet other eleven days ere the proud crest of Ben Nevis, the