This is one of four surviving instruments of similar design by the leading English instrument maker of the 16th century.
Developed from a simpler craft instrument, the wooden 'carpenter's rule', Humfrey Cole's device is a multipurpose instrument that could be used for surveying, map work and specialised calculation. It incorporates an inch ruler and scales of equal parts, as well as scales for reckoning areas and volumes. When equipped with sights it could be used to measure horizontal angles and, with the further addition of a plumb bob, vertical angles can be taken with its quadrant and shadow square.
Produced in expensive brass and neatly engraved, it demonstrates both the engagement of mathematical practitioners with practical tasks and also their distance from the humble instruments of craft practice.