embracing about one hundred square inches, out of which issues hot
vapor, the rocks adjoining changing color under the intense heat with
every breath blown upon them.

The tramp of our horses' feet as we rode over the incrustation at the
base of the mountain returned a hollow sound; yet while some of our
party were not disposed to venture upon it with their horses, still I
think with care in selecting a route there is very little danger in
riding over it.

On the mountain, large quantities of sulphur formed by the condensation
of the vapor issuing from the crevices, now closed, but once in activity
in the incrusted covering, have been deposited, and we collected many
specimens of pure and crystallized sulphur. Thousands of pounds of pure
and nearly pure sulphur are now lying on the top and sides of the
mountain, all of which can be easily gathered with the aid of a spade to
detach it from the mountain side incrustations to which it adheres in
the process of condensation. We gave to this mountain the name "Crater
hill."

Five miles further on we camped near the "Mud geyser." Our course to-day
has been for the greater part over a level valley, which was plainly
visible from the top of Mount Washburn. The water of the river at this
point is strongly impregnated with the mineral bases of the springs
surrounding our camp, and that empty into the river above it.


Friday, September 2.--To-day we have occupied ourselves in examining the
springs and other wonders at this point. At the base of the foot-hills
adjoining our camp are three large springs of thick boiling mud, the