Fleming Four-electrode valve. British patent 149, 422, 12 May 1919. (see also Fleming "Thermoinic Valve). 2 pairs of anodes (nickel) arranged symetrically around filament. Used as a detector. Bulb broken and almost entirely missing, anodes have therefore suffered also. Fleming Four-electrode valve. British patent 149, 422, 12 May 1919. (see also Fleming "Thermoinic Valve). 2 pairs of anodes (nickel) arranged symetrically around filament. Used as a detector. Bulb broken and almost entirely missing, anodes have therefore suffered also. There is a five pin base on the valve.
Asbestos Inspection - Non-Asbestos.
