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Keuffel & Esser 1741 Thacher Cylindrical Slide Rule

Stanley, William Ford

In 1881, Edwin Thacher, a "computing engineer" for the Keystone Bridge Company in Pittsburgh, Pennsylvania, received a patent for an improvement in slide rules. Thacher, a graduate of Rennselaer Polytechnic Institute, spent much of his career designing railway bridges. To assist in his calculations, he designed a cylindrical slide rule. Thacher's rule, though it fit on a desk, was equivalent to a conventional slide rule over 59 feet long. The rule had scales for multiplication and division and another scale, with divisions twice as large, for use in finding squares and square roots. There were no trigonometric scales.

Date

1890s

Type

calculating rule

Medium

metal (core, endposts material)

Department

NMAH

Institution

National Museum of American History

Object number

nmah_1131290

Credit

Transfer from Physics Department, U.S. Military Academy, Dept. of Defense