Look-Out Mountain, which stands a thousand feet above the surrounding country, between the Tennessee and Coos rivers, is one of the Alleghanies. Although the top is nearly level, it gives rise to a river which, after winding some distance, plunges abruptly over a precipice. Immediately below this fall, on each side, are bluffs two hundred feet high; one of which, by the turn of the stream, forms a kind of isolated peninsula. On the summit of this are the remains of a fortification, that follows the curve of the river below for more than thirty-seven rods, and extends to the very brow of the rock. The only descent and access is by a kind of fissure, which reaches to the shore beneath. Thirty feet from the top, intersecting this passage, is a ledge or platform ninety feet long by two to five wide. At this landing are five rooms, cut out of the solid rock. The entrance is small; but within they communicate with each other by doors or apertures. This wonderful excavation has the appearance of being intended as a place of the last resort for the inmates. From its peculiar position, twenty resolute men might successfully contend against the assault of a numerous army, as not more than one at a time can approach, and the slightest push would hurl an assailant over a precipice of a hundred and fifty feet to certain and instant death. That this is a remnant of antiquity there can be little doubt; and that it has escaped the attention of the curious, is owing, probably, to its retired and almost unknown situation. On the Ohio river, twenty miles below the mouth of the Wabash, is a remarkable cave, consisting of two rooms, one immediately over the other. The uppermost is accessible by a square opening; and the lowest is twelve rods in length and five in breadth. The interior walls are smooth. The floor is level through the centre, but the sides rise in stony grades, resembling the seats in the pit of a theatre; and leaving little doubt that it had been so arranged to accommodate an audience attending performances or deliberations of some nature. The engravings and hieroglyphics upon the walls are numerous and well executed. Many animals are represented, among which are eight that are now unknown. There are conical mounds in Ohio of various altitudes and dimensions, some being only four or five feet, and ten or twelve in diameter at the base; while others, farther south, rise even to a hundred feet, and cover many acres of ground. They are generally in the form of a cone. These structures seem to have been built at various periods; and it would be no matter of surprise if some of them were in existence during the deluge. The materials which compose them appear to be suited to their locations. In those positions where stone was not to be had, they are formed of earth.