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Image ModifiedKeuffel & Esser Desk Slide Rule, No. N-4096, c. 1930

This slide rule was “especially designed for the Merchant, Importer, Exporter, Accountant, Manager, Mechanic, Foreman, and others, whose computations involve only multiplication, division, proportion, and percentage.” (Keuffel & Esser Co. Catalogue, 38th Edition, 1936) This model includes DF, CF, CI, C, and D scales. Dr. Robert L. Berger, who owned this rule, began his career at the NIH in 1962 in the Laboratory of Technical Development, NHLBI. Over the course of 40 years, Berger developed a number of instruments used by scientists at the NIH. He holds two U.S. patents: the first in 1988 for the computer-controlled all-tantalum stopped-flow micro calorimeter; and the second in 1992 for the high-resolution digital thermometer. This thermometer could measure temperature differences to several micro-degrees centigrade and is a forerunner of the digital thermometers used today for cooking and taking temperatures. This slide rule is one of several belonging to Berger in the NIH Stetten Museum collection. See also 05.0014.003, Eugene Dietzgen Co. Midget Slide Rule and06.0005.001 Eugene Dietzgen Co. The Binary Slide Rule. 
[95.0006.003]

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