A planimeter made in Glasgow by McAughtry & Son, engraved with the name of the MV British Valour, an oil tanker launched in 1927 by Lithgows in Port Glasgow.
A planimeter would be used onboard a ship to calculate engine power – it can measure the area under a curved graph.
Good to see one so carefully preserved. I inherited my Grandfather’s planimeter – he used it when he supervised the building and testing of steam engines in the Lancashire cotton mills when he worked for Roberts Foundry of Nelson, Lancashire.