
Fechner's double sound pendulum for testing aural discrimination
1898-1908
1898-1908
1920-1939
1871-1900
1892
1850-1900
c.1963
1876
1923
1900
1901-1910
1900-1920
1871-1900
1871-1900
1875-1900
1870-1930
1870
1801-1900
1831-1870
1875-1900
1913
1900-1980
1889
1909
1875-1900
1926
1929
1850-1930
circa 1892