l of the mud-pots that give off a suppressed
thud as the gases burst their way through the stiff mortar. Sometimes
the mortar is as white as snow, or brown, or tinged with a variety of
vivid colors....

On the west side of the Fire-Hole, and along the little branch that
flows into it from the west, are numbers of springs of all grades, and
the broad bottom is covered with a snow-white silicious crust. Near the
base of the mountains there is a massive first-class boiling spring, in
a constant state of violent agitation, sending forth great columns of
steam, with a singular toadstool rim.... About three miles up the
Fire-Hole we meet with a small but quite interesting group of springs on
both sides of the stream. There is a vast accumulation of silica,
forming a hill fifty feet along the level of the river; upon the summit
one of the largest springs yet seen, nearly circular, one hundred and
fifty feet in diameter, boils up in the centre, but overflows with such
uniformity on all sides as to admit of the formation of no real rim, but
forming a succession of little ornamental steps, from one to three
inches in height, just as water would congeal from cold in flowing down
a gentle declivity. There was the same transparent clearness, the same
brilliancy of coloring to the waters, but the hot steam and the thinness
of the rim prevented me from approaching it near enough to ascertain its
temperature or observe its depth. It is certainly one of the grandest
hot springs ever seen by human eye.

But the most formidable one of all is near the margin of the river. It
seems to have broken out close by the river, and to have continually
enlarged its orifice by the breaking down of its sides. It evidently
commenced on the east side, and the continual wear of the under side of
the crust on the west side has caused the margin to fall in, until an
aperture at least two hundred and fifty feet in diameter has been
formed, with walls or sides twenty to thirty feet high, showing the
laminae of deposition perfectly. The water is intensely agitated all the
time, boiling like a caldron, from which a vast column of steam is ever
rising, filling the orifice. As the passing breeze sweeps it away for a
moment, one looks down into this terrible seething pit with terror. All
around the sides are large masses of the silicious crust that have
fallen from the rim. An immense column of water flows out of this
caldron into the river. As it pours over the