Dividers are used for measuring distances, in particular on charts and maps. Proportional dividers like these can also be used to enlarge or reduce distances by a set amount by fixing the locking screw at the appropriate point on one of the scales, and so can be used to transfer information between maps or charts drawn to different scales. The dividers are made of brass with steel points and have four different scales, marked ‘Planes’, ‘Solids’, ‘Circles’ and ‘Lines’, depending on how the instrument is being used. The original rayskin-covered case also survives. The maker’s name and address - 50, Holborn, London - are engraved next to the scales on the front of the dividers.