XII CHRONOLOGY OF ELECTRIC LIGHT 



1866 — Sir Charles Wheatstone invented the " self-excited " dynamo, 

 now universally used. 



1872 — Lodyguine invented an incandescent lamp having a graphite 

 hurner operating in nitrogen gas. 



1876 — Paul Jablochkoff invented the "electric candle," an arc light 

 commercially used for lighting the boulevards in Paris. 



1877-8 — Arc light systems commercially established in the United 

 States by William Wallace and Prof. Moses Farmer, Edward 

 Weston, Charles F. Brush and Prof. Elihu Thomson and 

 Edwin J. Houston. 



1879 — Thomas Alva Edison invented an incandescent lamp consisting 

 of a high resistance carbon filament operating in a high 

 vacuum maintained by an all glass globe. These principles 

 are used in all incandescent lamps made to-day. He also 

 invented a completely new system of distributing electricity 

 at constant pressure, now universally used. 



1882 — Lucien Goulard and John D. Gibbs invented a series alternat- 

 ing current system of distributing electric current. This has 

 not been commercially used. 



1886 — William Stanley invented a constant pressure alternating cur- 

 rent system of distribution. This is universally used where 

 current is to be distributed long distances. 



1893 — Louis B. Marks invented the enclosed carbon arc lamp. 



1898 — Bremer's invention of the dame arc lamp, having carbons im- 

 pregnated with various salts, commercially established. 



1900 — Dr. Walther Nernst's invention of the Nernst lamp commer- 

 cially 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 aii 

 had been exhausted to about a thousandth of an atmosphere. 

 High voltage current passing through this rarefied atmos- 

 phere caused it to glow. Rarefied carbon dioxide gas was 

 later used. 



