Fotos triode valve with two top caps (McVitie Weston valve collection), 1916-1972
1916-1972
1916-1972
1851-1900
1831-1870
1985
1896
1994
1994
1908
1753
1601-1700
1850-1880
1839
1911-1920
101-200 CE
1851-1900
1994
1994
1784
1908
50-300 CE
1994
1895/6
1783; 1914
circa 1896
1896
1896
1896
1784
1900-1920
1900-1920
1900-1920
1900-1920
circa 1899
1978-1980
circa 1905
1896
1772
1753
1896
1900-1920
1900-1920
1900-1920
1900-1920
1900-1929
1880-1910
1861