Woman examining Mullard valves, Radiolympia, Olympia, London, 1934.

Woman with Marconi transmitting valve, Radiolympia, London, 1936.

Brisez's bi-valve intra-uterine speculum, French, 1841-1900.

Driver's brake valve with feed valve. Secti

Marconi-Fleming valve radio receiver, c 1908.

Marconi-Fleming valve radio receiver, c 1908.

Marconi-Fleming valve radio receiver, c 1908.

Fleming diode, British, 1905.

Fleming diode, British, 1905.

Selection of valves, 1889-1906.

Radio valve of Clearton valve type.

Fleming's original thermionic valve, 1889.