Thirst, the water of the
lake being extremely salt, and there being no fresh streams
running into it.
Captain Bonneville doubts this report, or that the men
accomplished the circumnavigation, because, he says, the lake
receives several large streams from the mountains which bound it
to the east. In the spring, when the streams are swollen by rain
and by the melting of the snows, the lake rises several feet
above its ordinary level during the summer, it gradually subsides
again, leaving a sparkling zone of the finest salt upon its
shores.
The elevation of the vast plateau on which this lake is situated,
is estimated by Captain Bonneville at one and three-fourths of a
mile above the level of the ocean. The admirable purity and
transparency of the atmosphere in this region, allowing objects
to be seen, and the report of firearms to be heard, at an
astonishing distance; and its extreme dryness, causing the wheels
of wagons to fall in pieces, as instanced in former passages of
this work, are proofs of the great altitude of the Rocky Mountain
plains. That a body of salt water should exist at such a height
is cited as a singular phenomenon by Captain Bonneville, though
the salt lake of Mexico is not much inferior in elevation.
To have this lake properly explored, and all its secrets
revealed, was the grand scheme of the captain for the present
year; and while it was one in which his imagination evidently
took a leading part, he believed it would be attended with great
profit, from the numerous beaver streams with which the lake must
be fringed.
This momentous undertaking he confided to his lieutenant, Mr.
Walker, in whose experience and ability he had great confidence.
He instructed him to keep along the shores of the lake, and trap
in all the streams on his route; also to keep a journal, and
minutely to record the events of his journey, and everything
curious or interesting, making maps or charts of his route, and
of the surrounding country.
No pains nor expense were spared in fitting out the party, of
forty men, which he was to command. They had complete supplies
for a year, and were to meet Captain Bonneville in the ensuing
summer, in the valley of Bear River, the largest tributary of the
Salt Lake, which was to be his point of general rendezvous.
The next care of Captain Bonneville was to arrange for the safe
transportation of the peltries which he had collected to the
Atlantic States. Mr. Robert Campbell, the partner of Sublette,
was at this time in the rendezvous of the Rocky Mountain Fur
Company, having brought up their supplies. He was about to set
off on his return, with the peltries collected during the year,
and intended to proceed through the Crow country, to the head of
navigation on the Bighorn River, and to descend in boats down
that river, the Missouri, and the Yellowstone, to St. Louis.
