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).
