Fechner's double sound pendulum for testing aural discrimination
1898-1908
1898-1908
circa 1897
after 1903
1895
1908
1901
circa 1900
1909
1900
1899
1905
circa 1900
1903
1902
1900
1901
1896
1895
1896
1906
1902
1898
1901
1896
circa 1905
1906
1898-1899
1896
1904
1901
1898
1872 (original); 1909 (model)
1955; 1830
1901
1902-1907
1899
1898
1899
1903
1901
1899
1906
1895-1900
1903
1895-1905
1898
2000-100 BCE
1900-1909
1900-1909
1900