History of the Expedition Under the Command of Captains Lewis and Clark, Vol. 2. / To the Sources of the Missouri, Thence Across the Rocky Mountains and Down the River Columbia to the Pacific Ocean. Performed During the Years 1804-5-6.

by Meriwether Lewis; William Clark

r means rain.

s means snow.

h means hail.

t means thunder.

l means lightning.

a after, as f a r means fair after rain, which has intervened since the last observation.

c a s means cloudy after snow intervening.

c a r s means cloudy after rain and snow.

Notations of the river.

r means risen in the last 24 hours, ending at sunrise.