An uncommonlylarge diameter ebony rolling ruler. Ends are finished with turned rondels. Unmarked.
Length. 380 mm. (15 inches).
Rolling rulers were an essential tool for marine navigators. The primary requirement for a rolling ruler is that the timber not distort or bow. Very difficult to draw a straight line with a crooked ruler. Ebony has that stable characteristic and was used in the finest quality instruments. Other timbers such as mahogany and walnut were used but were not as successful as ebony.
Good condition with minor signs of usage and a small shrinkage crack on one end.
Probably eighteenth century.