of the river; however, I do not think they are formed by refluent water from that, because they are never turbid; because they do not rise and fall in correspondence with that in times of flood or of drought; and because the water is always cool. It is probably one of the many reservoirs with which the interior parts of the earth are supposed to abound, and yield supplies to the fountains of water, distinguished from others only by being accessible. The vault of this cave is of solid lime-stone, from twenty to forty or fifty feet high; through which water is continually percolating. This, trickling down the sides of the cave, has incrusted them over in the form of elegant drapery; and dripping from the top of the vault generates on that and on the base below, stalactites of a conical form, some of which have met and formed massive columns.

Another of these caves is near the North mountain, in the county of Frederic, on the lands of Mr. Zane. The entrance into this is on the top of an extensive ridge. You descend thirty or forty feet, as into a well, from whence the cave extends, nearly horizontally, four hundred feet into the earth, preserving a breadth of from twenty to fifty feet, and a height of from five to twelve feet. After entering this cave a few feet, the mercury, which in the open air was 50°, rose to 57° of Fahrenheit's thermometer, answering to 11° of Reaumur's, and it continued at that to the remotest parts of the cave. The uniform temperature of the cellars of the observa

tory of Paris, which are ninety feet deep, and of all subterraneous cavities of any depth, where no chemical agencies may be supposed to produce a factitious heat, has been found to be 10° of Reaumur, equal to 54% of Fahrenheit. The temperature of the cave above mentioned so nearly corresponds with this, that the difference may be ascribed to a difference of instruments.

At the Panther gap, in the ridge which divides the waters of the Crow and the Calf pasture, is what is called the Blowing Cave. It is in the side of a hill, is of about one hundred feet diameter, and emits constantly a current of air of such force as to keep the weeds prostrate to the distance of twenty yards before it. This current is strongest in dry, frosty weather, and in long spells of rain weakest. Regular inspirations and expirations of air, by caverns and fissures, have been probably enough accounted for by supposing them combined with intermitting fountains; as they must of course inhale air while their reservoirs are emptying themselves, and again emit it while they are filling. But a constant issue of air, only varying in its force as the weather is drier or damper, will require a new hypothesis. There is another blowing cave in the Cumberland mountain, about a mile from where it crosses the Carolina line. All we know of this is, that it is not constant, and that a fountain of water issues from it.

The Natural Bridge, the most sublime of nature's works, though not comprehended under the present