Check the listing for details. A Large 8in Brass Single Arm Protractor - C.T. Cooper, London.. Made in United Kingdom. Listed at 244.49 USD. English, c.1880, engraved, 'C.T. COOPER, 86 Gt DOVER St, LONDON', a large single arm brass protractor with vernier scale and locking nut, in velvet lined French polished mahogany case, case width 32cm.