Demonstration sextant, green-crackle finish aluminium frame, polished limb and wooden handle in fitted square wooden case, instrument unsigned but made by Francis Barker and Son, 12 Clerkenwell Road, London, 1925-1931. Consists of polished aluminium130° scale (0° to 130°) with 1° divisions and aluminium vernier (1’), no shade filters and pinhole sighting vane.