Surveyor's Vernier Compass
name: label: maker
content: W. & L. E. Gurley
notes: label: Description
content: This compass is marked "W. & L. E. Gurley Troy, N.Y." Since the signature--with its v-shaped trenches and lines of varying weight--was clearly engraved by hand, the compass was made between 1852 when the Gurleys began in business, and before the middle of 1876, when their new engraving machine was up and running.
label: Description
content: The variation arc on the south arm extends 20 degrees either way; the vernier is moved by a tangent screw, also on the south arm, and reads to 2 minutes. Two level vials are on the north arm. The side of one vertical sight is graduated to half degrees for determining angles of elevation or depression. In 1871, a compass of this size and design cost $50.
label: Description
content: Ref: W. & L. E. Gurley, <i>A Manual of the Principal Instruments Used in American Engineering and Surveying</i> (Troy, N.Y., 1871), pp. 23-27.
label: Description
content: W. Skerritt, "W. & L. E. Gurley's Engraving Machine," <i>Rittenhouse</i> 11 (1997): 97-100.
label: Location
content: Currently not on view
place: label: place made
content: United States: New York, Troy
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
publisher: label: Related Publication
content: W. & L. E. Gurley. Manual of the Prinicipal Instruments Used in American Engineering and Surveying; 17th Edition
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.328411
label: catalog number
content: 328411
label: accession number
content: 272530
objectType: label: Object Name
content: Surveyor's Compass
physicalDescription: label: Measurements
content: overall length: 15 1/2 in; 39.37 cm
label: Measurements
content: needle: 6 in; 15.24 cm
label: Measurements
content: overall in case: 9 5/8 in x 15 3/8 in x 6 7/8 in; 24.4475 cm x 39.0525 cm x 17.4625 cm