Fechner's double sound pendulum for testing aural discrimination
1898-1908
1898-1908
1986
1884-1936
1850-1897
1854
c.1910
circa 1912
circa 1910
circa 1920
1953-1958
circa 1930
circa 1910
circa 1890
1819
1825
1829
1930
1940-1945
1910-1919
1910-1919
1910-1919
1825; 1910
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1910-1919
1970-1985
1876
1876