42 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. '](i 



SUB-DIVIDING THE ELECTRIC LIGHT 



While the arc lamp was being commercially established, it was at 

 once seen that it was too large a unit for household use. Many inven- 

 tors attacked the problem of making a smaller unit, or, as it was 

 called, " sub-dividing the electric light." In the United States there 

 were four men prominent in this work : WilHam E. Sawyer, Moses G. 

 Farmer, Hiram S. Maxim and Thomas A. Edison. These men did 

 not make smaller arc lamps but all attempted to make an incandescent 

 lamp that would operate on the arc circuits. 



Sawyer's Incandescent 

 Lamp, 1878. 



This had a graphite burner 

 operating in nitrogen gas. 



Farmer's Incandescent 

 Lamp, 1878. 



The graphite burner oper- 

 ated in nitrogen gas. This 

 lamp is in the collection of the 

 Smithsonian Institution. 



Sawyer made several lamps in the years 1878-79 along the lines of 

 the Russian scientists. All his lamps had a thick carbon burner 

 operating in nitrogen gas. They had a long glass tube closed at one 

 end and the other cemented to a brass base through which the gas 

 was put in. Heavy fluted wires connected the burner with the base 

 to radiate the heat, in order to keep the joint in the base cool. The 

 burner was renewable by opening the cemented joint. Farmer's lamp 

 consisted of a pair of heavy copper rods mounted on a rubber cork, 

 between which a graphite rod was mounted. This was inserted in 

 a glass bulb and operated in nitrogen gas. Maxim made a lamp 

 having a carbon burner operating in a rarefied hydrocarbon vapor. 

 He also made a lamp consisting of a sheet of platinum operating in air. 



