The cathode rays passing through the aperture may be bent by an electromagnet. Made of clear glass, unmarked. Long glass tube with cylindrical bulb one end. Tube has two terminals, cathode plate and sealed exhausting tube at one end, midway is a metal cylinder with one closed end having an aperture. Bulb end has a disk target approximately the full inside diameter.
RCA demonstrated electronic television at the 1939 World’s Fair and other manufacturers quickly began to develop products. Allen B. Dumont Laboratories already produced one of the main components, cathode ray tubes or CRTs. Dumont made these tubes for oscilloscopes but understood they would also serve as picture tubes. This tube has a 3.5 inch face with a white phosphor. The clear envelope allows one to see the electron gun mechanism that produces the stream of cathode rays.
Marked: "149" inked on press. Stamped with Dumont maker's stamp and "Globe Television and Phone Corp." Paper label handwritten: "Fil. Current 5.6A Med[?] Elect. -20V Accel. Elect. +840V Accel. Current 250 microamps" Fil = filament, accel = accellerator. Dumont provided tubes for its own sets and for other manufacturers like Globe Television and Phone Corp. of Boston. Globe made mechanical television sets in the early 1930s and presumably was moving into electronic television.
Crookes tube for demonstrating cathode ray independence of positive pole, marked: "P1B2". Pear-shaped construction. Concave focusing cathode is mounted in tube with three rod-type anodes. Five inch glass stem forms base of tube. Purpose of the tube was to trace the path of an electron beam through a partial vacuum by observing luminosity patters as positive voltage was applied to each anode. Reference: Crookes, "On Radiant Matter," 1881, pages 11-14.