Details
A collection of ivory scales and rules,
comprising a 1-foot scale by Troughton & Simms, three sectors, one signed Potter Poultry London, another Wellington London, the other unsigned, a miniature rolling parallel rule and three scales, and a brass and ivory scissor-action parallel rule
comprising a 1-foot scale by Troughton & Simms, three sectors, one signed Potter Poultry London, another Wellington London, the other unsigned, a miniature rolling parallel rule and three scales, and a brass and ivory scissor-action parallel rule