From the journal of Meriwether Lewis, written at camp at the top of the Corps of Discovery’s portage around the Great Falls of the Missouri:

not having seen the Snake Indians or knowing in fact whether to calculate on their friendship or hostility or friendship we have conceived our party sufficiently small and therefore have concluded not to dispatch a canoe with a part of our men to St. Louis as we had intended early in the spring. we fear also that such a measure might possibly discourage those who would in such case remain, and might possibly hazzard the fate of the expedition. we have never once hinted to any one of the party that we had such a scheme in contemplation, and all appear perfectly to have made up their minds to suceed in the expedition or purish in the attempt. we all beleive that we are now about to enter on the most perilous and difficult part of our voyage, yet I see no one repining; all appear ready to met those difficulties which wait us with resolution and becoming fortitude… since our arrival at the falls we have repeatedly witnessed a nois which proceeds from a direction a little to the N. of West as loud and as resembling precisely the discharge of a piece of ordinance of 6 pounds at the distance of three miles… I have thout it probable that it might be caused by runing water in some of the caverns of those immence mountains, on the principal of the blowing caverns; but in such case the sounds would be periodical & regular, which is not the case with this, being sometimes heard once only and at other times, six or seven discharges in quick succession. it is heard also at different seasons of the day and night. I am at a loss to account for this phenomenon. our work being at an end this evening, we gave the men a drink of sperits, it being the last of our stock, and some of them appeared a little sensible of it’s effects the fiddle was plyed and they danced very merrily untill 9 in the evening when a heavy shower of rain put an end to that part of the amusement tho’ they continued their mirth with songs and festive jokes nd were extreemly merry untill late at night. we had a very comfortable dinner, of bacon, beans, suit dumplings & buffaloe beaf &c. in short we had no just cause to covet the sumptuous feasts of our countrymen on this day.