BOX SEXTANT OUTFIT WITH GIMBALLED ARTIFICIAL HORIZON MIRROR

BOX SEXTANT OUTFIT WITH GIMBALLED ARTIFICIAL HORIZON MIRROR

Stock Number: 8220

$4500.

For sale, antique box sextant, complete and in very fine condition. This is an unusual design with a weighted mirror to provide a horizontal reflecting surface.

Dimensions

2-3/4 inch diameter (7 cm)

Circa

c.1820

Categories: Maritime, Navigational instruments

Description

BOX SEXTANT OUTFIT WITH GIMBALLED ARTIFICIAL HORIZON MIRROR, English, c.1820, signed “Simms, London.” The 2-3/4″ (7 cm) diameter brass sextant is complete with inlaid silver scale and one-arcminute vernier, scale magnifier, geared index arm, mirror adjusting tool, peepsight, single draw telescope, two swing-away filters, and screw-on handle/cover. The cover is engraved with tables of tangents and arctangents. The original fitted mahogany case contains a weighted plane mirror in double gimbal rings, which sets up on folding supports in the case top. This is a novel approach to providing a perfectly horizontal reflecting surface; in use one measures the angular distance from a star, the sun, or even a coastal landmark, to its reflection in the mirror. Half this will be the altitude of the object, determined without reference to the horizon itself, which may be obscured by haze, etc. Condition is very fine throughout. This is one of the few known instruments produced by a member of the Simms family of nautical and mathematical instrument makers. Made prior to William (II)¹s partnership with Edward Troughton beginning in 1826, it is the only example of this unusual design we have come across. 

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US TESSERACT

David and Yola Coffeen both have enjoyed academic careers, as planetary astronomer and as linguist/educator. But since 1982 (yes, 1982!) they have been full-time dealers in early scientific and medical instruments, under the name Tesseract. Selling primarily by catalogue (over 100 issued so far) they also have a web presence at www.etesseract.com, and can be contacted at mail@etesseract.com.

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