Electron tubes, also known as vacuum tubes

Electron tubes.

DRY RECTIFIERS, ELECTRON TUBES, BARRETTERS; TRANSISTORS, SEMI-CONDUCTOR DEVICES; PHOTO CELLS, CATHODE RAY TUBES

SCIENTIFIC, NAUTICAL, SURVEYING, NAVIGATING, PHOTOGRAPHIC, CINEMATOGRAPHIC, OPTICAL, WEIGHING, MEASURING, MEASURING AND RECORDING, INDICATING, INDICATING AND RECORDING, METERING, TELEMETERING, SIGNALLING, CHECKING (SUPERVISION) APPARATUS AND INSTRUMENTS; TIMING DEVICES, CALCULATING AND COMPUTING APPARATUS AND INSTRUMENTS; PARTS OF ALL THE AFORESAID GOODS; AND INDICATOR LAMPS OF ALL KINDS

ELECTRIC GENERATORS AND MOTORS; ELECTRIC ENGINES; TELEGRAPHIC, TELEPHONIC AND WIRELESS TELEGRAPHIC AND WIRELESS TELEPHONIC INSTRUMENTS AND APPARATUS AND PARTS THEREOF; RHEOSTATS; ELECTRIC SIGNALLING APPARATUS; ACCUMULATORS; BATTERIES; INDUCTION COILS; MAGNETOS; APPARATUS FOR ELECTROLYSIS AND FOR EPILATION; ELECTRICAL GOODS AND FITTINGS OF ORDINARY METAL WHICH INCLUDES ELECTRIC LIGHT PENDANTS, BRACKETS, AND STANDARDS; ELECTRIC SWITCHES, FUSES, AND CUTOUTS; METALLIC TUBING AND FITTINGS FOR THE ...

Natural gas

Electron tubes, also known as vacuum tubes