r the storm was over, they proceeded to a fountain, perhaps the
largest in America. It is situated in a pleasant, level plain, and about
twenty-five yards from the river, into which it falls over some steep,
irregular rocks.

In this part of the country a remarkable phenomenon was noticed. A loud
report, precisely resembling the sound of a cannon, was repeatedly heard
from the mountains, at different times, both of the day and night;
sometimes in one stroke; at others, in five or six successive
discharges. This report was occasionally heard when the air was
perfectly still and without a cloud; and it was supposed to be
occasioned by the bursting of rocks.

The party, continuing indefatigable in their exertions, dragged the
canoes, or pushed them along with poles, up the current of the Missouri.
This they did, day after day, until the 27th of June, when they arrived
at the _Three forks of the river_; that is, at the point at which three
rivers, each of considerable size, flow together, and form the great
stream. As it was difficult to determine the largest of the three,
Captains Lewis and Clarke decided on discontinuing here the appellation
of Missouri; and named the streams, respectively, Jefferson's,
Madison's, and Gallatin's river. As the first of these flowed from the
west, they ascended it in preference to the others; but they continued
to experience great difficulty with the canoes, in consequence of the
rapidity of the current.

They were now approaching the termination of the first great division of
their journey. The river continued to lessen as they proceeded: its
width, in the part at which they arrived on the 8th of July, was not
more than forty yards; and, on the 11th, it was diminished to twelve, so
as to admit of being waded over without hazard. They had now proceeded,
by computation, three thousand miles from the mouth of the Missouri; and
they, not long afterwards, reached its extreme navigable point, in
latitude 43 degrees 30 minutes, and nearly in longitude 112 degrees west
from Greenwich.

Here they laid up their canoes, until they should return from the
Pacific ocean; and, proceeding by land, had the gratification of tracing
the current to its _fountain head_, in the midst of the Rocky Mountains.

Seventeenth Day's Instruction.

WESTERN TERRITORY CONTINUED.

_Narrative of_ LEWIS _and_ CLARKE'S _Travels from the
Source of the Missouri to the Pacific Ocean._

From the source of the Mi