Periscopic bubble aircraft sextant, Type 1A, No. 2053, by Kelvin and Hughes (Aviation) Limited, Barkingside, Essex, England, 1950-1951. The periscopic bubble aircraft sextant was used on the De-Havilland Comet passenger jet aircraft. Periscopic bubble aircraft sextant: Type 1A, No. 2053 Navigation 1950-1951
