1904—D. McFarlan Moore’s invention of the Moore vacuum tube light commercially established. This consisted of a long tube, made in lengths up to 200 feet, from which the air had been exhausted to about a thousandth of an atmosphere. High voltage current passing through this rarefied atmosphere caused it to glow. Rarefied carbon dioxide gas was later used.
1905—Dr. Auer von Welsbach’s invention of the osmium incandescent lamp commercially established, but only on a small scale in Europe. The metal osmium, used for the filament which operated in vacuum, is rarer and more expensive than platinum.
1905—Dr. Willis R. Whitney’s invention of the Gem incandescent lamp commercially established. The carbon filament had been heated to a very high temperature in an electric resistance furnace invented by him. The lamp was 25 per cent more efficient than the regular carbon lamp.
1906—Dr. Werner von Bolton’s invention of the tantalum incandescent lamp commercially established.
1907—Alexander Just and Franz Hanaman’s invention of the tungsten filament incandescent lamp commercially established.
1911—Dr. William D. Coolidge’s invention of drawn tungsten wire commercially established.
1913—Dr. Irving Langmuir’s invention of the gas-filled tungsten filament incandescent lamp commercially established.
HISTORY OF ELECTRIC LIGHT
By HENRY SCHROEDER,
HARRISON, NEW JERSEY.