Stock Number: 9200


For sale, antique flat drum sextant of brass, similar to that of Adams/Jones description and illustration. Larger than a normal box sextant, but no thicker and complete with cover and case.


4-1/2 inches (3.6 cm) diameter


first half 19th century

Country of manufacture

UK and Ireland

Categories: Maritime, Navigational instruments


FLAT DRUM SEXTANT, English, c. first half 19th century, constructed of brass, 4-1/4″ (11 cm) in diameter and 1-5/8″ (3.6 cm) thick, the interior with “wriggle-work” designs and fine clear lacquer finish, the exterior of chemically darkened brass. A geared index arm carries an internal mirror, and is set with a silver vernier divided to one arc-minute. This reads against the 0° – 122° inset silver scale. There is a scale magnifier on long arm, and separately insertable dark red index and horizon filters. The sextant cover can be screwed onto the opposite side to serve as handgrip, and to avoid loss. The instrument itself is quite handsome, and fully functional, but we note a crack and chips to the cover¹s threads, and some edge damage to the sextant surround. The interior lacquer finish is excellent, the exterior rubbed and worn.

This is an unusual form of pocket “box” sextant, considerably larger in diameter than most, and yet no thicker. It is similar to that described and illustrated in Adams’/Jones’ Geometrical and Graphical Essays of the late 18th century (although here with interior rather than exterior rack work). For an Adams example see Tesseract Catalogue 38 Item 55.

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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 [email protected].

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