Antique quality ivory folding sector in near mint condition circa mid 19th century. Made by Troughton and Simm of London. Scale measures 30.5cm (12 inches) open. Overall dimensions closed are 16cm x 3.6cm.
 
Troughton & Simms was a British instrument-making firm, formed when Edward Troughton took on William Simms as a partner in 1826. It became a limited company in 1915 and in 1922 merged with T. Cooke & Sons to form Cooke, Troughton & Simms. The firm produced high quality astronomical instruments and drawing instruments used around the world. In 1876, they supplied the Imperial Standards Of Length gauges mounted at Trafalgar Square in London UK.