Smithsonian - National Museum of American History, Behring Center

Physical Sciences Collection - Surveying and Geodesy

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Surveyor's Compass - click to enlarge

Surveyor's Compass - click to enlarge

Click photos to enlarge.

Surveyor's Compass

Catalogue number:

"Lynch * Dublin *"

length 18.25 inches; needle 5.5 inches


Some American surveyors and instrument makers working in the second half of the 18th century may have been familiar with Irish compasses like this one, which was probably made by the eldest of the three men named James Lynch who worked in Dublin during the period 1767-1846. This compass is made of brass, and the face is silvered. The rose reads counterclockwise, a feature that David Rittenhouse introduced to American practice in the 1760s. The vertical sights are held with a narrow and relatively flimsy bar. The graduated needle rim reads clockwise to 360 degrees, rather than in quadrants from north and south as was usually the case. There is another graduation at the outer edge of the face, numbered in quadrants from north and south. The compass box can be detached from the bar.

Ref: J. E. Burnett and A. D. Morrison-Low, "Vulgar and Mechanick" The Scientific Instrument Trade in Ireland 1650-1921 (Dublin, 1989), pp. 29-35.

Gloria Clifton, Directory of British Scientific Instrument Makers 1550-1851 (London, 1995).

Further Information:

David Rittenhouse
Surveyor's Compass