


Lot 28
THACHER CYLINDRICAL SLIDE RULE MODEL 4012 No 3117, New York: Keuffel & Esser, c.1910,
3 – 4 November 2021, 13:00 PDT
Los AngelesUS$800 - US$1,200
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THACHER CYLINDRICAL SLIDE RULE MODEL 4012
No 3117, New York: Keuffel & Esser, c.1910, multi-faceted cylindrical slide rule with wood end caps, affixed to wooden base by brass guides, instructions to base, mahogany lided case with matching serial number, Keuffel & Esser label inside case lid, 545 x 144 x 135 mm (21 1/2 x 5 5/8 x 5 1/2 inches).
*WITH: THACHER, EDWIN. Directions for Using Thacher's Calculating Instrument. New York: Keuffel & Esser, 1910. Original linen-backed wrappers.
Edwin Thacher was an engineer at the Keystone Bridge Company. He designed the circular slide rule, which was patented in 1881, to assist in his calculations designing railway bridges. The cylindrical form allowed for what would be a 59-foot conventional slide rule to take up less than 2 feet. The rule includes scales for multiplication and division as well scales for finding squares and square roots.
*WITH: THACHER, EDWIN. Directions for Using Thacher's Calculating Instrument. New York: Keuffel & Esser, 1910. Original linen-backed wrappers.
Edwin Thacher was an engineer at the Keystone Bridge Company. He designed the circular slide rule, which was patented in 1881, to assist in his calculations designing railway bridges. The cylindrical form allowed for what would be a 59-foot conventional slide rule to take up less than 2 feet. The rule includes scales for multiplication and division as well scales for finding squares and square roots.