NO. 2 



HISTORY OF ELECTRIC LIGHT SCHROEDER 



33 



first large installation of the arc light, and was the beginning of its 

 commercial introduction. Henry Wilde made some improvements 

 in the candle by eliminating the kaolin between the carbons which 

 gave Jablochkoff's arc its peculiar color. Wilde's arc was started by 

 allowing the ends of the carbons to touch each other, a magnet swing- 

 ing them apart thus striking the arc. 



Jablochkoff's Alternating Current Dynamo, 1876. 



This dynamo had a stationary exterior armature and internal re- 

 volving field poles. Alternating current was used for the Jablochkoff 

 " candle " to overcome the difficulties of unequal consumption of the 

 carbons on direct current. 



COMMERCIAL INTRODUCTION OF THE DIFFERENTIALLY CONTROLLED 



ARC LAMP 



About the same time Lontin, a Frenchman, improved Serrin's arc 

 lamp mechanism by the application of series and shunt magnets. This 

 is the differential principle which was invented by Lacassagne and 

 Thiers in 1855 but which apparently had been forgotten. Several 

 of these lamps were commercially installed in France beginning with 

 1876. 



ARC LIGHTING IN THE UNITED STATES 



About 1875 William Wallace of xA.nsonia, Connecticut, made an 

 arc light consisting of two rectangular carbon plates mounted on 

 a wooden frame. The arc played between the two edges of the plates, 



