
The Ardente Hearing aid, London, England, 1920-1930
1920-1930
1920-1930
1920-1925
1921-1930
1839 (original); circa 1988 (replica)
1926
1920-1929
1930
1920-1925
1925
1928
1921
1934
1931
1927
1924
circa 1930
1920
1928
1922
1924
1928
1926
1921
1920
2000-100 BCE
1920-1928
1920-1928
before 1928
1921-1931
1955; 1830
1925-1928
1927-1929
circa 1920
1930-1931
1920
1923
circa 1930
1931
1927
1927
1926
1922-1923
1922-1923
1922-1923
1922-1923
1921-1926
1925
1920-1929
1920-1930
1920-1930