Aircraft bubble sextant.
1942-1945
1942-1945
1931
1950
1936
1955
1948
1890-1920
1890-1920
1942-1945
circa 1914
circa 1912
1910
1910-1915
1923-1933
1890-1920
circa 1912
1939
circa 1960
circa 1960
circa 1948
1930
circa 1930
1915-1925