Pilot balloon slide rule Mk II
1940
1940
1890
1939
1950
1955-1967
1940-1945
1946
1960-1965
1920-1925
1910-1915
1960
1895-1905
1955
circa 1890
1960-1967
1960-1965
1960
1960-1970
1958
1880-1890
1905-1915
1935-1940
1885-1895
1942
1920-1930
1910
1960-1965
1960-1965
circa 1910-circa 1930
1905-1915
1910-1911
1965
1965
1955-1965
1915-1925
circa 1960
1950-1960