Thatcher's Calculating Instrument by Keuffel & Esser Co.

Description:

Thatcher's Calculating Instrument by Keuffel & Esser Co., New York, patd. by Edwin Thatcher 1881, with rotating paper-covered inner cylinder and outer scales, on mahogany base with printed instructions and rules for operation, including multiplication, proportion, square roots, cube roots and simple interest, lg. 21 in., in stained wood case with maker's plaque.
Estimate $1,000-1,500

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