Models of three wooden prisms used by Heinrich Hertz, 1949
1949
1949
1949
1950
1980-1950
1949
1938 and 1951
1955; 1830
1950
1950
1950
1949
1950
1950
2000-100 BCE
circa 1950
1949
circa 1950
1949
1949
1949
1950
1950
1950
1950
1903 (original); 1982 (model)
1950
4000-2001 BCE
1949
1949
1839 (original); circa 1988 (replica)
circa 1950
1990-96
1950
circa 1950
1949
1949
1950
1949
1950
1949
circa 1950
circa 1950
c.1950
c. 1950
circa 1950
circa 1950
1950
1950s
1950
1950