surveyor's compass
Date: circa 1850
Inventory Number: 5192a
Classification: Surveyor's Compass
Subject:
Maker: Benjamin Pike, Jr. (1809 - 1864)
Cultural Region:
Place of Origin:
Dimensions:
without sights: 6.1 × 37.4 × 14.7 cm (2 3/8 × 14 3/4 × 5 13/16 in.)
case without object in it: 5.1 × 38.9 × 18.7 cm (2 × 15 5/16 × 7 3/8 in.)
Accessories: carrying case
Bibliography:
Pike's Illustrated Descriptive Catalogue of Optical, Mathematical, and Philosophical Instruments
Description:
All brass instrument with two removable sighting vanes. Both have a narrow slit and four circular apertures. There are two bubble levels, one on each arm positioned at a right angle and forming a "T", to level in both axes of the horizontal plane.
The silver dial's face has eight cardinal points, with a fleur-de-lys for identifying North. Degrees are engraved on the raised scale (0-90°-0-90°), divided in half degrees and marked to every ten. The glass cover of the compass is missing. The instrument is supported by a ball-and-socket joint and a tripod.
When not in use, the instrument is stored in a wooden box, the top of which is missing.
The silver dial's face has eight cardinal points, with a fleur-de-lys for identifying North. Degrees are engraved on the raised scale (0-90°-0-90°), divided in half degrees and marked to every ten. The glass cover of the compass is missing. The instrument is supported by a ball-and-socket joint and a tripod.
When not in use, the instrument is stored in a wooden box, the top of which is missing.
Signedon dial, engraved: Benj. Pike Jr. / 294 Broadway / New York
FunctionThe surveyor's compass is an instrument used in surveying (or in navigation in rare cases) to measure horizontal angles, what is called bearing or azimuth.
For a nice discussion of this intrument, see the following website.
For a nice discussion of this intrument, see the following website.
Primary SourcesBenjamin Pike Jr., Pike's Illustrated Descriptive Catalogue of Optical, Mathematical, and Philosophical Instruments, 2 vols. (New York: Benjamin Pike, Jr., 1856) 2: 60-64.