
Automatic building level, British, 1957
1957
1957
1970
1959
1948-1960
1954
1959
1955
1950-1954
1943-1948
1970
1960-1965
1970-1996
1954-1964
1959
1950-1959
1961
1959
circa 1970
1959
1959
1955
1953-1954
1957
1960
1953-1954
circa 1940s-circa 1950s
1953-1954
1949
1959
1948-1960
1948-1969
1967-1968
1959
1958
1905-1968
1950
1956-1959