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

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

Driver's brake valve with feed valve. Secti

Radio valve of Clearton valve type.

Muffled 'pop' safety valve, c 1875. Section

Diode valve, early 20th century.

V24 and Q amplifying valves, c 1920s.

Marconiphone crystal-valve radio receiver, 1923.

Valve-operated radio, 1955.

Radio pick-up arm, 1932 and klystron valve, 1940.

5-valve R1 Radio receiver, 1922.

Ros 'pop' safety valve, c 1904. This is a