Perrygraf Clipper Cargo Dimensional Weight Computer Circular Slide Chart

This instrument consists of concentric turquoise and white paper discs and a paper indicator held together with a metal rivet. Around the edge of the turquoise disc is a logarithmic scale of weight in pounds that ranges from 2 to 1,000. Inside this is a scale of lengths from 10" to 50". The white disc has a scale of heights from 5" to 50" and a scale of widths from 6" to 50". The indicator has a scale in densities in cubic inches per pound from 100 to 300 and instructions for setting the dimensions and density of a parcel in order to read off the parcel's weight.

The indicator is marked: PAN AMERICAN WORLD (/) AIRWAYS (/) 506 West Sixth Street (/) Los Angeles 14, California (/) Phone: Michigan 2121 (/) CLIPPER CARGO (/) Dimensional (/) WEIGHT COMPUTER. The white disc is marked: Clipper, Trade Mark, Reg. U. S. Pat. Off. Printed in U.S.A. (/) Copyright 1951, Pan American World Airways, Inc. (/) Slide-Chart by PERRYGRAF, Maywood, Ill. The back of the instrument has a Pan Am compass rose logo at the center of advertising text: ANY WAY YOU MEASURE (/) MAKE CLIPPER CARGO YOUR RULE (/) For All Your Export Shipping (/) See Us For A Free Cost Analysis of (/) CLIPPER CARGO SERVICE (/) via PAN AMERICAN WORLD AIRWAYS.

A slide chart is a slide rule that performs a specific calculation, usually commissioned by a company as a promotional item. In 1934, machinery inspector Lester E. Perry (1901–1991) came up with the idea of equipping salespeople with slide charts so that they could immediately answer customers' questions. Perrygraf Corporation, the company he established in the Chicago, Ill., suburbs, quickly became a dominant force in this market. Pan Am was the principal international air carrier in the United States for most of the 20th century. See also 1996.3029.02, whose copyright date suggests that the latest date this chart was made was 1957.

References: George Melloan, "Pocket Slide Charts Aid Engineers, Help Sell Steel, Lipstick," Wall Street Journal, September 4, 1953, 1; "People: Perrygraf," Waywiser, Harvard University Department of the History of Science website.

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