SIGHTING QUADRANT FOR DISTANCE RANGING OF TALL SHIPS, ETC.
Stock Number: 10192
For sale, antique English brass sighting quadrant, which can be used for astronomical or surveying angular altitudes. However, there is a small scale on the reverse which identifies this for maritime use.
6-1/4 inches (16 cm) tall
c. early 19th century
Country of manufacture
UK and Ireland
SIGHTING QUADRANT, English, c. early 19th century. This all-brass instrument stands 6-1/4″ (16 cm) tall, with cross-hair equipped sighting tube moving in altitude over the 0(1)90 degree quadrant, and swinging freely in azimuth on the short pillar mount. Sighting horizontally the scale reads 0°; vertically, 90°. Thus we have a straightforward astronomical quadrant measuring angular altitudes of celestial bodies as well as topographic features, buildings, etc. But a small scale, with index pointer, on the reverse tells a further story, and speaks of probable maritime use. Covering altitudes of less than 8°, this scale is divided from 500 yards to 2000 yards and beyond. The 500 yard mark corresponds to about 7.°25, which is the angular height of an object about 190 feet tall, at that distance. Few things on land have such a typical height but it is a reasonable estimate for the mast heights of the tallest sailing ships. For example, we find in 1830 the 1300 ton merchant ship had a main mast of 179 feet. Contained in a somewhat stained simple pine box, this unusual instrument is in very fine condition.
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 firstname.lastname@example.org.