ivory sector
Datecirca 1825
Inventory NumberDW0942
ClassificationSector
Subject
Maker
J. Jackson
Cultural Region
Place of Origin
Dimensions0.3 x 16.5 x 3.6 cm (1/8 x 6 1/2 x 1 7/16 in.)
Material
DescriptionThe sector, or military compass, consists of two equally sized rectangular ivory rules attached with a brass pivot disc and end plating. There are several sets of plane and angled measurements on both sides of the sector in black engraved lettering.
On the signed side of the instrument, each half has three rules. They are marked, from top to bottom, "L" and "P" in engraved black letters opposite the pivot end. On the other side of the instrument, each half has two angled scales. The scales are marked "C" and "S" at the end opposite the pivot. At the bottom of one of these back halves is a two line gunnery scale marked "Diam guns*" and "Diam shot*".
On the signed side of the instrument, each half has three rules. They are marked, from top to bottom, "L" and "P" in engraved black letters opposite the pivot end. On the other side of the instrument, each half has two angled scales. The scales are marked "C" and "S" at the end opposite the pivot. At the bottom of one of these back halves is a two line gunnery scale marked "Diam guns*" and "Diam shot*".
Signedengraved in black script on brass plate on upper arm of front side: J. Jackson
engraved in black script on brass plate on lower arm of front side: London.
Curatorial RemarksSent by David P. Wheatland about 1985 to Christie's, New York for auction (Christie's tag DC830/220). Returned to the Collection of Historical Scientific Instruments in 1988 at William Andrewes' request.
FunctionThe ivory sector and its many sets of measurements are used to facilitate various mathematical calculations from trigonometry to square roots. The sector is also called a military compass because of its immense utility for navigation and gunnery calculations.
ProvenanceDavid Wheatland acquired from R. Wormser in 1950.
Charles W. Dixey
Date: circa 1830
Accessories: silver framed green shagreen case
original curatorial cards and photos
Object number: DW0288
George Adams (I)
Date: circa 1766
Accessories: original case
Object number: DW0955
T. and T. Blunt
Date: circa 1820
Accessories: rectangular sharkskin covered wood case
Object number: DW0712
Elliott Brothers
Date: circa 1863
Accessories: wooden case; bill of sale and the dealer's tag, in the instrument's file
Object number: DW0489
