Laboratory standard a.c. and d.c. (electrodynamometer) voltmeter with 12 inch scale
1952
1952
circa 1946
circa 1960
1941
1955
1964
1985
24 February 1951
1949-05-06
1949-05-06
circa 1919
1959
1953
1950-1960
circa 1954
1949-05-06
1949-05-06
1949-05-06
1964-01-21
1955-1960
1950
circa 1955
1930
1949
1912-1920
1919
circa 1971
1953
1955
1921-1930
1948-05-05
1949