NO. 2 



HISTORY OF ELECTRIC LIGHT SCHROEDER 



43 



EDJSON S INVENTION OF A PRACTICAL INCANDESCENT LAMP 



Edison began the study of the problem in the spring of 1878. He 

 had a well-equipped laboratory at ]\Ienlo Park, New Jersey, with 

 several able assistants and a number of workmen, about a hundred 

 people all told. He had made a number of well-known inventions, 

 among which were the quadruplex telegraph whereby four messages 

 could be sent simultaneously over one wire, the carbon telephone 

 transmitter without which Bell's telephone receiver would have been 



Maxim's Incandescent Lamp, 1878. 



The carbon burner operated in a rarefied hydrocarbon vapor, 

 lamp is in the collection of the Smithsonian Institution. 



This 



impracticable, and the phonograph. All of these are in use today, so 

 Edison was eminently fitted to attack the problem. 



Edison's first experiments were to confirm the failures of other 

 experimenters. Convinced of the seeming impossibility of carbon, 

 he turned his attention to platinum as a light giving element. Realiz- 

 ing the importance of operating platinum close to its melting tempera- 

 ture, he designed a lamp which had a thermostatic arrangement so 

 that the burner would be automatically short circuited the moment its 

 temperature became dangerously close to melting. The burner con- 

 sisted of a double helix of platinum wire within which was a rod. 



