Kegelman Stadia Reduction Computer Circular Slide Rule


This white plastic circular rule has a clear plastic indicator attached with a metal grommet in the center. The rule has scales of H (horizontal factor), theta (vertical angle), and V (vertical factor). A diagram on the instrument gives the formulas for these factors. The instrument is marked: KB (/) STADIA REDUCTION COMPUTER (/) KEGELMAN BROS. (/) HUNTINGDON VALLEY PA. (/) COPYRIGHT, 1956 (/) BY WILLIAM KEGELMAN P.E. It is in a cream-colored paper envelope stamped: WILLIAM KEGELMAN (/) 393 COUNTY LINE ROAD (/) HUNTINGDON VALLEY, PA.

George Kegelman (1900–1985) began his career with Heller & Brightly of Philadelphia. He established his own shop around 1943 and began to work with his brother, William (1907–1985). In 1951, the pair formed Kegelman Brothers, which became best known for its Model 101 engineers transit. William Kegelman received a copyright (A245443) for this device, which was intended to process readings taken with the transit, on July 9, 1956.

For other slide rules for reducing data from observations made with stadia rods, see MA.333636, 1977.1141.41, 1983.0472.01, 1987.0221.01, and 1987.0221.02.

References: Robert C. Miller, "George Kegelman and Kegelman Brothers: Mathematical and Optical Instrument Makers," Rittenhouse 5 (1991): 56–58; Charles E. Smart, The Makers of Surveying Instruments in America Since 1700 (Troy, N.Y.: Regal Art Press, 1962–1967); Catalog of Copyright Entries: Books and Pamphlets, 3rd ser. 10 (1956): 324, 1161; Kegelman Bros., Instruction Manual for Engineers Transit (Hunting[d]on Valley, Pa., 1957) 9–10 (see 2001.0282.02).

Date Made: after 1956

Maker: Kegelman Bros.

Location: Currently not on view

Place Made: United States: Pennsylvania, Lower Moreland Township

Subject: Rule, CalculatingMathematicsSurveying


See more items in: Medicine and Science: Mathematics, Science & Mathematics, Slide Rules


Exhibition Location:

Credit Line: Gift of Robert C. Miller

Data Source: National Museum of American History

Id Number: 2001.0282.01Accession Number: 2001.0282Catalog Number: 2001.0282.01

Object Name: calculating ruleslide rule

Physical Description: plastic (overall material)metal (part material)paper (part material)Measurements: rule: 12.9 cm; x 5 1/16 inoverall: 13.2 cm x 13.2 cm x 13.2 cm; 5 3/16 in x 5 3/16 in x 5 3/16 inenvelope: 13.3 cm x 13.3 cm; 5 1/4 in x 5 1/4 in


Record Id: nmah_875008

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