.
Dakota Geological Survey, p. 48, says: 'This phenomenon is found to
correspond with the varying pressure of the barometer, and with its
single opening and capacious chambers is easily accounted for.'

"The rushing air is sometimes strong enough to require a man's weight to
open the entrance door. Five days and nights is the longest time the
wind has been known to move in one direction without ceasing. This is
one of nature's greatest atmospherical phenomena.

"Some one says, 'Tickets, please!' and into the hole we go, single file
down a lighted passageway to where we can light our candles. After
descending about one hundred and fifty-five feet we come into the Bridal
Chamber (named by some of the earlier explorers before the present
management took hold of the property), which is eight or ten feet in
length by twenty feet in breadth. Passing along some distance, the
Snow-ball Room is entered. It carries this name on account of little
rosettes of carbonate of lime sticking to the irregular ceiling. This
room is pretty narrow and some fifty feet in length.

"The Post Office is next and soon reached. The ceiling is covered with
the box work formation somewhat resembling Post Office boxes. You will
no doubt wonder why it carries such a common name.

"Just because after searching in what books on geology and other
sciences we could get, we could not find it described nor any formation
resembling it; hence its common name, as we have named the pop-corn
work, frost work etc., from their appearance.

"The dimensions of the Post Office are some eighty feet in length by
twenty feet in width, with an average ceiling height of probably twelve
feet. Red Hall is the room next in order, and has on either side a red
bank of sandy, micaceous clay.

"Just to the left is a very pretty little grotto of box work. This room
is very odd in make-up. The floor is very rough and dips about fifteen
feet in its length of sixty feet, and includes a short flight of stairs.
The lowest end of the room is prettily decorated, and some pleasing
blends of color attract the eye. To the left is the Old Maids' Grotto, a
pretty little nook that would please any maid old or young.

"After passing through the White Room we turn to the left along the
crevice, and after traveling some little distance reach The Grand Opera,
a very narrow room but some forty feet in length. Chopin's Nocturne is a
small grotto in the right hand wall named by the famous viol