No caves have been discovered in the Bad Lands, unless that name be applied to some of the geodes which are really grottoes, they being of sufficient size for a man to stand in.  The Black Hills, however, contain some of the most remarkable caves ever yet discovered, of which those of greatest importance are Wind Cave and the three Onyx Caves near Hot Springs, in the southeastern part of the Hills, and Crystal Cave near Piedmont, in the northeast.  All of these occur in the Carboniferous Limestone which forms an outer belt around the central mass or core of the Hills and no doubt, as previously suggested, owes its fissures to earthquakes which preceded or accompanied the porphyry intrusions by which in some localities its strata have been thrown into a vertical position.

CHAPTER IX.

Wind cave.

Wind Cave was discovered in 1881 by a hunter named Thomas Bingham, who being weary of a fruitless chase sat down to rest, and was soon startled by the sound of rushing wind on a calm day; and at the same time by a singular hair-raising sensation, as his hat was lifted from his head and thrown high in the air.  He is said to have afterwards declared that although frightened nearly out of his wits, he determined to find the cause of his alarm, and on turning slightly discovered a hole about eight by twelve inches in size through which a roaring wind was issuing from the earth.  As his hair maintained the aggressive attitude taken, the recovered hat could not be returned to its usual place, so an hour was spent in laying it across the opening and watching its instant projection into upper space; after which he set out to tell of the wonderful discovery.  The announcement, however, was not received seriously and he was assured of the impossibility of the wind blowing through a hill of solid rock, and his brother explained to him that he had been too self-indulgent and consequently imagined the whole affair.  A protest of total abstinence failed to inspire confidence, but the brother promised to go the next day to see for himself, and did.  The hat was again placed over the opening as before, but instead of taking the expected lofty flight, it was drawn in and has never since been seen:  the current had reversed.  Soon after this the hole was enlarged to eighteen by thirty inches and the cave entered by quite a number of venturesome persons assisted by a long rope and ample personal courage.  No other improvements were made, and only a short distance was explored, until Mr. J.D.  McDonald settled on the property in 1890; since which time he and his sons have explored ninety-seven miles of passage and done such extensive work in opening up small passages and placing ladders, that it is now possible for visitors to travel long distances with surprising ease and comfort.  The measure of distances in the cave is not by the usual guess-work method which has established the short-measure reputation for cave miles, but is done with a fair degree of accuracy by means of the twine used to mark the trail in exploring new passages.  A careful measurement of the twine has shown it to run nine balls to the mile with a close average of regularity, so it is the custom to add another mile to the cave record as often as a ninth ball becomes exhausted.