Such fires not being made by hunters so late in the season, it was supposed they were caused by some wandering war parties.

These often take the precaution to set the prairies on fire behind them to conceal their traces from their enemies.
This is chiefly done when the party has been unsuccessful, and is on the retreat and apprehensive of pursuit.

At such time it is not safe even for friends to fall in with them, as they are apt to be in savage humor, and disposed to vent their spleen in capricious outrage.

These signs, therefore, of a band of marauders on the prowl, called for some degree of vigilance on the part of the travellers.
After passing the Nebraska, the party halted for part of two days on the bank of the river, a little above Papillion Creek, to supply themselves with a stock of oars and poles from the tough wood of the ash, which is not met with higher up the Missouri.

While the voyagers were thus occupied, the naturalists rambled over the adjacent country to collect plants.