Smithsonian - National Museum of American History, Behring Center

 
Physical Sciences Collection - Surveying and Geodesy

Browse Makers | Browse Instruments | Index

Back
 

Surveyor's Compass - click to enlarge

Click photos to enlarge.

Surveyor's Compass

Catalogue number:
1985.0798.01

Inscriptions:
"JAMES REED & CO. Pittsburg, Pa. No. 383"

Dimensions:
telescope 17.75 inches

Discussion:
This compass, which was designed to measure horizontal and vertical angles on hilly ground or in mines, resembles the one that the American surveyor, Lucius Lyon, described in 1828. It also resembles the Hedley's dial, devised in 1850 by John Hedley, H. M. Inspector of Mines in England. This example consists of a gimbal-mounted vernier compass, a vertical arc, and a sighting telescope, and hanging level. The variation arc and vernier mechanisms are located on the compass face, under glass and protected from harm. The vertical arc is solid, graduated to 30 minutes, and read by vernier to single minutes.

James Reed (1792-1878) was first listed in the Pittsburgh directories in 1847 as a watch maker and jeweller. He began trading as James Reed & Co. in 1850, and in 1852 advertised as "Manufacturers of theodolites, surveyors compasses, leveling & grading instruments, &c. . ."

Lucius Lyon, "Observations on Surveying Instruments, and the means of remedying their imperfections," American Journal of Science 14 (1828): 268-275.

Ref: William Ford Stanley, Surveying and Levelling Instruments (London, 1901), pp. 311-319.

Further Information:

Surveyor's Compass

Back