
Clockwork timer used by renal dialysis patients
1940-1980
1940-1980
1997-1999
1930-1960
1939-1949
1970-1984
1940-1974
1968
1968
1968
1960-1975
1904-1910
1980-1984
1940-1974
1920-1930
1920-1930
1946
circa 1955
circa 1919
1903-1913
circa 1946
patented 1908
1970-1979