The Wind Cave lies ten miles north of Hot Springs on U.S. 85A. The cavern is the focal point of interest in its own National Park, which takes in forty square miles. Nearly half of this park is enclosed with a high fence, behind which one of the last great bison herds roams contentedly. Protected antelope, elk, and deer also enjoy this game preserve. The cavern was discovered, according to legend, by a cowboy who heard a continued low whistling noise in the weeds and, investigating, found air rushing from a ten-inch hole near the present entrance to the cave. And indeed it is this very phenomenon that makes Wind Cave different from other notable caverns, such as the one at Carlsbad. Even on the stillest of days a steady current of air can be felt rushing in or out of the cave’s opening—into the earth if the barometer is rising, and out of the ground if the pressure is falling. The National Park Service conducts tours of the cave, the complete excursion lasting some two hours. Fortunately, although the visitor descends to a great depth as he searches out the various chambers on the route, the tour ends at an elevator which whisks him swiftly to the surface near the starting point. The entire cavern is a little more than ten miles long, although there are portions of it which have not even yet been explored so that their size may be known with accuracy. It is not graced with the growths of stalactites and stalagmites normally to be found in limestone formations, but nature has compensated for that lack by fashioning a peculiar box-work which looks for all the world as if the cavern had been subjected to an interminable frosting process. These beautiful fretwork deposits, which are not to be found in any other cave, are the result of a strange chemical process that took place in the limestone stratum where Wind Cave is located. Surface water seeping into the stone became charged with carbon dioxide gas from the decaying organic matter through which it passed. This gentle acid then dissolved the limestone only to redeposit it in cracks and crevices around other limestone fragments. The precipitated limestone was of a different chemical composition and resisted later onslaughts by the eroding acids—which, however, did eat away the fragments around which the precipitate had formed, leaving the maze of hollow crystalline formations that can be seen in the various chambers of the cavern. The National Park, being relatively small, is not equipped with overnight facilities; but this does not matter, for the town of Hot Springs is but twenty minutes’ drive from the park, and the town of Custer is only twenty miles away. There are, however, camping grounds in the park, and the Park Service operates a lunchroom at the entrance to the cave. _Custer State Park_