Hemmi Simplex Slide Rule Retailed by Post (1447)

This ten-inch one-sided bamboo rule is coated with white celluloid only on the front. There is no indicator. The base has A, D, and K scales. The slide has B, CI, and C scales on one side and S, L, and T scales on the other side. The CI scale is numbered in red. The base is held together with a sheet of metal and with clear celluloid that has red hairlines at each end. The back of this metal and celluloid backing contains a chart on white plastic. The chart provides various relationships or conversions between the C and D scales as well as fundamental trigonometric relationships.

The instrument is marked in red at the top center of the base: FREDERICK POST CO. 1447. It is marked in black at the top right: HEMMI JAPAN. The Post logo (in red) appears at the right side of the slide. The back is stamped with the date code TD, indicating the rule was manufactured in April 1969. The style of the Post logo is consistent with this date.

The Frederick Post Company of Chicago imported slide rules made by the Japanese firm of Hemmi from about 1932 to the 1970s, with a brief interruption during World War II. Post sold Model 1447 from about 1949 to about 1971.

Chemist Albert S. Matlack donated this slide rule. He recalled that it was mainly used by his laboratory technician at the Hercules Research Center in Wilmington, Del.

References: International Slide Rule Museum, "Slide Rule Dates and Time-Lines," http://sliderulemuseum.com/SR_Dates.htm; Drafting Materials for Engineering, Architecture, and Art by Post, 19th ed. (Chicago: The Frederick Post Co., 1949–1950), 68–69; Carmen Drahl, "The Guy With the Questions at NOS: Albert S. Matlack," 7 June 2011, http://cenblog.org/newscripts/2011/06/the-guy-with-the-questions-at-nos-albert-s-matlack/..

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