106 



TABLE 94.— INCREASE IN TUNGSTEN LAMP EFFICIENCY OVER A 

 PERIOD OF YEARS 



Date 



Lamp measured 



100-watt squirted filament 1908 t 



100-watt drawn wire 1909 1 



100-watt drawn wire 1915 t 



100-watt gas-filled 1921 



100-watt gas-filled 1932 



100-watt gas-filled 1936 



100-watt gas-filled * 1936 



100-watt gas-filled * coiled coil 1948 



* 750 hours life. t Vacuum lamps. 



TABLE 95.— TEMPERATURE AND EFFICIENCY OF SOME TUNGSTEN- 

 FILAMENT LAMPS* 



* Data furnished by W. E. Forsvthe and E. M. Watson, of the General Electric Co. t These 

 values furnished by W. H. Fisher, Nela Park. t Vacuum lamps, all others are gas-filled. § Tem- 

 perature at junction of base and bulb. || Area of coil in mm 2 . H Candlepower in direction used. 

 * Color temperature. 



(continued) 



SMITHSONIAN PHYSICAL TABLES 



