Brass sextant with polished brass diamond-pattern frame and limb, with wooden handle in fitted mahogany keystone case by John James Messer, London, England, 1845-55. Consists of inlaid polished silver 131° scale (-5° to 145°) with 15’ divisions and silver vernier (15”), four index-filter shades (red & green), three horizon filters (orange), scale magnifier on 90mm swivelling arm. Fitted with threaded telescope bracket for sighting telescopes (84mm – erect image & 146mm – inverted image) and sighting tube (83mm).