Mammoth Cave.
(Continued From No. 5.)
The cave, which here commences to grow wider and higher, also becomes more rough and rugged, until reaching the Rocky Mountains, a succession of high hills, formed of detached fragments of rock, at times rising to the height of one hundred feet. The last and highest of the "mountains," upon the side that overlooks "Dismal Hollow," is two hundred feet from its summit to the level of the cave beyond. Truly, this "dismal hollow" is well deserving of its name. From the top of the mountain it appears like a bottomless gulf. The abyss covers an area of eight acres, and its depth cannot be seen, for want of sufficient light.
In "Serena's Arbor," which we entered after climbing over rocks, for some distance, are many beautiful formations of crystallized limestone. Among them are two stalagmites, worthy of notice. One of them is a representation of a cedar tree, and its perfectly correct in shape and proportion; the other is a miniature of the celebrated "Cleopatra's Needle."
A pit, one hundred and sixty feet deep, terminates this avenue, at the distance of thirteen miles from the mouth of the cave. There are other avenues or branches equally wonderful with the one described. Indeed, the cave as far as explored seems to be but one of the several caves of equal grandeur and extent one lying above another. The branches leading from the main cave, as already discovered, are two hundred and sixty-five in number, of which there are many extensive ones unexplored. The shortest of these is one-fourth of a mile, and the longest, is nearly ten miles in length. In exploring that portion of the cave which we have endeavoured to describe, we walked thirty-five miles. We were lowest, beneath the surface of the earth, when upon the rivers, having then made a descent of three hundred and twenty-five feet. There are several large bodies of water in the cave, many springs, pure and sulphurious, and numerous cascades, of which "Harrison's Cascade" is the largest, falling the depth of sixty feet. The only salts in the cave, are the sulphates of magnesia and soda. The formations are principally of crystallized limestone, sulphate of lime, crystallized and fibrous gypsum, olophelite spar, and petrified mud.
In the winder season, great numbers of bats are found hanging to the ceiling in a state of torpor. A white semi-transparent, and blind species of cricket are occasionally seen; also, in the rivers, blind fish from three to five inches in length, perfectly white and transparent, together with craw fish, which possess the same peculiarities. We could discover, on examination, no place or sockets for the eyes, in either; on the contrary, the head was smooth on the top and sides, without the least inequality or indentation.
The air is agreeable and exhilarating, making the pulse beat full and strong, and respiration is performed with perfect freedom. The contrast, on emerging into the open air, is so great as almost to produce suffocation and fainting; the external air being loaded with a thousand disagreeable odors and being heavy and feverish. This is caused by the extreme purity of the atmosphere within the cave, which is always, during both summer and winter, of about the same temperature, (60º Fahrenheit.) Hence the air within appears warm in winter and cool in summer. During the former season there is a constant current of air blowing into the cave, sufficiently strong to extinguish a lighted candle or lamp while in the summer, the current is reversed. This circulation is a preservation against fire damp of which there is none in the cave.