Beam compass no. 1173A by Houghton-Butcher Manufacturing Co. Ltd., London, 1918, with accessories in original fitted box Beam compass no. 1173A by Houghton-Butcher Manufacturing Co. Ltd. 1918
Beam compass, tubular, divided on silver to 1/20th inch; reads by vernier to 1/1000th inch; clamp and slow motion; numbered to 45 on brass; extension tube numbered from 46 to 65, divided as above Beam compass