J. Agee photo
Lewis's preliminary list of supplies and equipment needed for the expedition, drawn up in the spring of 1803, included blue beads. "This is a coarse cheap bead," he wrote, "imported from China, & costing in England 13 d. the lbs., in strands. It is far more valued than the white beads of the same manufacture and answers all the purposes of money, being counted by the fathom [six feet]."
His point was confirmed by January 9, 1806, when he wrote:
A few weeks later (Mar 19, 1806) he added:
The Chinooks called blue beads tiaqmusaks, meaning "chief beads."
1. In troy weight–the standard in the Medieval French trading city of Troyes for measuring precious metals and the like--a pennyweight equals 24 grains, or 1/20 of an ounce. A troy pound equals 12 ounces. About how many of those beads of moderate size would there be in a troy pound?
Goods such as sugar, salt, dyes, and grain were measured in avoirdupois weight (from French avoirdepois, or "goods of weight"). An avoirdupois pound contains 7,000 grains, or 16 ounces at 16 drams per ounce. An avoirdupois pound equals about 1.22 troy pounds. Then there was the stone, equal to 14 pounds, etc.
Measurements of volume were even more complicated and confusing--the corn gallon, corn bushel, wine gallon, ale gallon, etc., etc. In short, weights and measurements in Lewis and Clark's day were so complicated as to be practically meaningless.
One of the most important outcomes of the French Revolution was the adoption, in 1799, of the simpler, logical, consistent metrical system of weights and measures, "for all people, for all time." Yet it was not generally accepted in France until 1840. After that, it was taken up in Latin America, the Soviet Union, China, and Japan. The United States signed on, in principle, in 1875, but in the practical, everyday terms we are still weighed down by parts of the old systems. Meanwhile, a new International System of Units has replaced the "old" metric system.