Philosophical instruments, scientific instruments, and apparatus for useful purposes, instruments and apparatus for teaching, electronic discharge devices, gas discharge tubes, electronic valves, cathode-ray tubes, television pick-up tubes, vacuum tubes, electric switches, glass to metal terminal seals, vacuum measuring devices, quartz crystals, germanium diodes, transistors and other semi-conducting devices for use in electric and electronic apparatus,

Vacuum or partial vacuum devices, and apparatus and instruments embodying such devices, all included in this class; particularly discharge tubes in general, cathode-ray tubes, vacuum tubes or valves, radio and television receiving tubes or valves, radio and television transmitting tubes or valves, electric lamps,