Brass sextant with black-lacquered brass frame, polished limb, wooden handle and fitted keystone mahogany case, by Johann August Daniel Oertling, Berlin, Germany, 1835-1845. Consists of inlaid polished silver 125° scale (-10° to 150°) with 10’ divisions and silver vernier (10”), three index-filter shades (red & green), three horizon filters (red & green), scale magnifier on 80mm swivelling arm. Fitted with threaded telescope bracket for sighting telescopes (missing) and sighting tube (83mm – tube).