Filar micrometer by William Herschel, 1780-1800
1780-1800
1780-1800
1925
1795-1825
1989-1999
1970-1980
1960
1950-1970
1951-1970
1950-1959
1950-1959
Unknown date
1960-1975
1984
1984
1795-1825
Unknown
Unknown
Unknown
Unknown
1960-1975
1850-1900
1850-1900
1935-1965
1980
1937
1920-1950
1939
1950-1980
1850-1900
1940-1965
1939
1964
1938-1950
1970-1978
1984
1961
1950-1959
1964
1950-1959
1960
1934
1976-1981
1931-09-28
1939
Unknown
circa 1967
1972
1950-1959
1950-1959