The "J. Allan, Baltimore" inscription on this sextant is that of John Allen (b. 1786), an "optician and mathematical instrument maker" listed in Baltimore city directories from 1810 to 1819. He was the son of James Allen, a noted instrument maker in London. And he boasted: "As all Instruments sold by me are graduated by my father’s improved self-correcting engine, for which the Society of Arts voted him their Gold Medal, on the 19th of May, 1810–they are warranted and will be kept in repair one year, gratis."

This sextant has a brass frame. The silvered scale is graduated every 20 minutes from -5° to +145° and read by vernier with tangent screw and magnifier to 30 seconds of arc.

Ref: Deborah J. Warner, "American Octants and Sextants: The Early Years," Rittenhouse 3 (1989): 86-112, on 89.

John Allen advertisement in the American & Commercial Daily Advertiser (June 12, 1816).

Date Made: 1810-1819

Maker: Allen, John

Location: Currently not on view

Place Made: United States: Maryland, Baltimore

See more items in: Medicine and Science: Physical Sciences, Navigation, Measuring & Mapping


Exhibition Location:

Credit Line: College of the Holy Cross

Data Source: National Museum of American History

Id Number: PH.326932Accession Number: 264083Catalog Number: 326932

Object Name: sextant

Measurements: radius: 7 in; 17.78 cmoverall in box: 5 1/8 in x 12 3/4 in x 10 3/4 in; 13.0175 cm x 32.385 cm x 27.305 cm


Record Id: nmah_1183788

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