e mountainous, but not by any
means to the extent required to furnish the series of peaks above
mentioned.

Captain Sublette, in one of his early expeditions across the mountains,
is said to have sent four men in a skin canoe, to explore the lake,
who professed to have navigated all round it; but to have suffered
excessively from 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