Surveyor's Vernier Compass
name: label: maker
content: Young, William J.
notes: label: Description
content: This compass marked "Wm. J. Young Maker Philadelphia" has two notable features. One is that the variation arc and vernier mechanism are located on the compass face, under glass and protected from harm. A similar design appears in the drawing accompanying William J. Young's 1830 patent application for an "Improved Surveying Compass." That instrument, however, had a full divided circle rather than a small variation arc. The other feature of this compass--a dark face and a silvered needle ring--was also described in Young's patent, and seems to be found on all Young compasses with a needle 5 inches or longer. The <i>Journal of the Franklin Institute</i> 10 (1832): 34, explained that this improvement of Young's "consists in colouring the surface of the compass plate green, or bronzing it, instead of silvering it in the usual way, thereby relieving the eye from the unpleasant and injurious effects of the white plate. A narrow silvered rim surrounds the bronzed surface, giving a distinct view of the needle point."
label: Description
content: This compass dates from the late 1840s or early 1850s, after the expiration of Young's patent and before Young began placing serial numbers on his instruments. The variation arc extends 20 some degrees either way, and is graduated to 30 minutes. The vernier is moved by rack and pinion located on the south arm and hidden under a brass plate, and reads to single minutes. There is an outkeeper and a level vial (now missing) on the north arm.
label: Description
content: Ref: D. J. Warner, "William J. Young. From Craft to Industry in a Skilled Trade," <i>Pennsylvania History</i> 52 (1985): 53-68.
label: Location
content: Currently not on view
place: label: place made
content: United States: Pennsylvania, Philadelphia
setName: label: See more items in
content: Medicine and Science: Physical Sciences
label: See more items in
content: Surveying and Geodesy
label: See more items in
content: Measuring & Mapping
creditLine: label: Credit Line
content: Gettysburg College
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 1982.0104.03
label: accession number
content: 1982.0104
label: catalog number
content: 1982.0104.03
objectType: label: Object Name
content: surveyor's compass
physicalDescription: label: Measurements
content: overall length: 15 in; 38.1 cm
label: Measurements
content: needle: 5 5/8 in; 14.2875 cm
label: Measurements
content: overall in case: 5 3/8 in x 16 1/8 in x 8 1/4 in; 13.6525 cm x 40.9575 cm x 20.955 cm