Rotating Mathematical Table, Sinclair's Freight Computer

By the late 1860s, railroads were vital to American commerce. This is the U.S. patent model for a rotating multiplication table used to compute freight charges. It was patented by Albert Sinclair of West Waterville, Maine, in 1869.

The instrument has a cylindrical metal case painted black, with metal feet at each end. The case contains a rotating cylinder covered with a printed table of numbers, which represent amounts charged for shipping given quantities of freight at given rates. A long narrow opening across the case shows one line of this table. The rate charged (from 1 to 50 cents per hundred pounds) is given at the far left of the table, with total fees indicated for weights from 1 to 9, 10 to 100 (by tens), 200 to 1,000 (by hundreds), and 10,000 to 50,000 (by ten thousands) pounds. A paper sticker glued above the window lists these weights, as well as the cost of shipping the weights for rates of 1/4 cents, 1/2 cents, and 3/4 cents per hundred pounds. Such costs are added on to the figure shown in the table if the rate is not a whole number.

A blue paper sticker pasted to the case below the window gives instructions. A mark on it reads: SINCLAIR'S FREIGHT COMPUTER (/) FOR RAILROADS AND GENERAL FREIGHTING BUSINESS, (/) By the use of which, all multiplication and division in computing Freight is dispensed with. A reward of Ten Dollars is offered to the first person who can find an error of one cent in the computation of this machine or table.

Albert Sinclair also took out a patent for a broom earlier in 1869. The 1870 U.S. Census lists an Albert Sinclair, boardinghouse keeper, living in Lewiston, Maine, with his wife, Martha, and several children. Lewiston is about fifty miles southwest of Waterville. The 1860 census lists this Albert Sinclair and his family as living in Kalmar, Minnesota, where he was a farmer, thirty-nine years old, and born in Maine.

References:

U.S. Census records.

Albert Sinclair, “Broom,” U.S. Patent 92,483, July 13, 1869.

Albert Sinclair, “Improvement in Price-Calculating Devices,” U.S. Patent 97,974, December 14, 1869.

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