Tavernier-Gravet Mannheim Simplex Slide Rule

This fourteen-inch boxwood Mannheim linear slide rule has a brass indicator in the single chisel style with an open interior. There are no endpieces. The top edge is beveled and has a scale of 35 centimeters, divided to millimeters. The top of the base has a scale divided logarithmically from 1 to 10 twice, and the bottom of the base has a scale divided logarithmically from 1 to 10. These are the usual A and D scales, although they are not lettered.

One side of the slide has the same two scales (the usual B and C scales, although they are not lettered). The other side of the slide has a scale of tangents that runs from 0 to 45 degrees and is lettered T; a scale of equal parts that runs from 0 to 1,000; and a scale of sines that runs from 80 to 0 and is lettered S. Compare to MA.318474. A paper table glued to the back gives geometric formulae, physical constants for the latitude of Paris, units of measure in France and in England, rates of exchange for common currencies, specific gravities, expansion coefficients of various gases, temperatures of melting and boiling for various solids and liquids, and similar data.

The bottom of the base is marked: TAVERNIER – GRAVET; RUE MAET 19.PARIS. The back is marked: MÉDAILLES D'OR 1878 ET 1889. Keuffel & Esser donated this rule to the Smithsonian. As with MA.318473, K&E imported it to sell while the company developed the ability to manufacture its own slide rules. Also like MA.318473, the scales and indicator resemble the ten-inch model 479–2 (subsequently numbered 1746N and 1746), but a rule of this length (scales about 14" long) is not listed in K&E catalogs. The ten-inch version with brass indicator cost $4.50 between 1883 and 1890. In 1892, the single-chisel indicator was replaced with a double-chisel indicator.

References: Florian Cajori, A History of the Logarithmic Slide Rule and Allied Instruments (New York: Engineering News Publishing Company, 1909), 55–58, 80–81; Francis Wells and Tom Wyman, "La Règle à Calcul: Lenoir, Gravet-Lenoir, and Tavernier-Gravet Slide Rules," Journal of the Oughtred Society 11, no. 1 (2002): 23–27; Bob Otnes, "Keuffel & Esser — 1880 to 1899," Journal of the Oughtred Society 10, no. 1 (2001): 18–28; Catalogue of Keuffel & Esser, 17th ed. (New York, 1883), 93; Catalogue of Keuffel & Esser, 20th ed. (New York, 1887), 129; Catalogue of Keuffel & Esser, (New York, 1890), 131.

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