The surveyor’s compass on display is the actual one carried on the expedition by William Clark and was used for the magnetic azimuth measurements. In his journal, Lewis noted that he purchased a ”surveying compass with extra needles“ for $23.50. At one point on the expedition, Clark lost the compass in a flash flood. He found it the next day.”
This item is on loan to the exhibition from the National Museum of American History, Smithsonian Institution.