An unusual large oxidised brass double index mirror drum sextant signed Negretti & Zambra London, with the Government War Department Mark numbered 2, inset silver arcs on both sides of the drum reading 5°-0°-160° (and with further engraved scale to 180°), swivel magnifiers, fixed mounting telescope with rotating coloured shades to eyepiece, folding mahogany handle, in leather carrying case - overall length 9in.(23cm)