1900--Dr. Walther Nernst’s invention of the Nernst lamp commercially established. The burner consisted of various oxides, such as zirconia, which operated in the open air. 1901--Dr. Peter Cooper Hewitt’s invention of the mercury arc light commercially established. 1902--The magnetite arc lamp was developed by C. A. B. Halvorson, Jr. This has a new method of control of the arc. The negative electrode consists of a mixture of magnetite and other substances packed in an iron tube. 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. EARLY RECORDS OF ELECTRICITY AND MAGNETISM