EXCEPTIONAL DIRECT-PLOTTING SEXTANT
Stock Number: 10222
For sale, an antique direct plotting sextant designed to chart angles without mathematics. In excellent nearly new condition.
5-3/4 x 6 inches (15 cm)
Country of manufacture
EXCEPTIONAL DIRECT-PLOTTING SEXTANT, Austrian, c.1840, signed “C.E. Kraft in Wien.” This lovely sextant measures 5-3/4″ tall and 6″ (15 cm) wide overall, of clear lacquered brass with blued steel screws and shaped wood handle. It is fitted with clampable index arm and mirror, half-silvered horizon mirror rotatable by thumbscrew below, and sighting tube. The angular scale is divided directly on the brass, every degree from 0 to 140 (but useable only to 122° making this a true sextant); readout is against a spring-loaded screw-adjustable vernier on the index arm, divided every four arcminutes. This fine little sextant has an added direct-plotting feature, with a fixed shaped steel tip on the body corresponding to the 0° position, and a similar tip on the index arm. Condition is excellent, near new throughout.
With this instrument any angular separation can be immediately plotted as a distance on chart paper. The conversion is in fact quite simple; at 45° the points are exactly 5 cm apart, and at 90°, 10 cm. We have seen a few other sextants with this feature, noting a similar one by Kraft but with a different vernier geometry (Bennett, 1987, The Divided Circle, Fig. 99), one by Lenoir of Paris, and one by Brander and Höschel (Kern, 2010, vol. 3, item 143). The quality of workmanship and finish is like that of Pister and Martins in Berlin (see Tesseract Catalogue 94 Item 25). Carol Eduard Kraft established his instrument workshop in Vienna in 1823, and is listed in directories through mid-century. He followed in the fine traditions of craftsmanship of Voigtländer and of Starke.
Ask the Dealer
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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