ELECTRIC LIGHTS. 



'59 



ELECTRIC LIGHTS FOR 

 PROJECTION. 



Since this book was first published Electric lighting 

 has become a great industry, and most remarkable 

 advances have been made in the economy of pro- 

 duction of electricity, and in the devices for its utiliza- 

 tion. Compare the statement 

 made on pages 9 and 10 with 

 what any one may see in any 

 city and in hundreds of towns 

 here and in Europe. Arc lights 

 of great steadiness are made by 

 many makers, and the carbons 

 adapted to them are plentiful 

 and to be had for a few cents 

 apiece. Consequently one may 

 now have an arc light for 

 projection experiments in al- 

 most every place. A regulator 

 is not specially needed, for the 

 carbons burn but slowly, about 

 an inch an hour, and hand 

 regulation does not much inter- 

 fere even with extended lec- 

 tures, while the brilliancy of 



J HA-WKRIDGK s ELECTRIC LAMPS 



the pictures surpasses many FOR PROJECTION. 



times the best possible with the oxyhydrogen light, 

 but an automatic regulator is a great convenience. 

 The ordinary electric lamps are so made as to feed 



