34° 



Tables 363-365 



TABLE 363. — Characteristics of Sunlight Mazda Lamp (SI) 300 Watts a.c. Combined Incandescent 

 Tungsten, Mercury Arc, Special High Transmission Bulb 



For more detailed data see Taylor, Journ. Opt. Soc. Amer., 21, 20, 1931 ; Forsythe, 

 Barnes, Easley, loc.cit. p. 30, Gen. Electr. Rev., 33, 358, 1930. 



Characteristics of Si lamp: distance between electrodes 

 5.4 mm. Current 31 + amp., voltage 11 volts; light output 

 5670 lumens. Efficiency, 17.6 lumens/watt ; % light from 

 mercury arc, 20 ; light from filament 100 lumens ; max. temp, 

 electrodes 3200 K, of filament 2330° K. Temp, of Hg 

 285° C, pressure of Hg vapor, 177 mm Hg. 



Transmission of 1 mm of glass used : 



X in Angstroms 2500 2600 2700 2800 2900 3100 3300 



% transmissible 10 20 33 52 67.5 88 89 



Energy Flux in Microvolts/cm 2 



3500 

 90 



4000 

 92 



5000 

 92 



Si 

 Lamp * 



Below 2000 A 0.6 



2900-3000 2.4 



2800-3100 7.7 



2900-3200 19.3 



Sun 

 t 



0.0 

 0.64 



24. 

 140. 



im from center of arc. 

 In center of beam. 



t 3.75 amp. 72 v in lamp, no reflector. 

 J Directly overhead. 



Per cent Total Energy Flux in various Spectrum Regions 



* Includes Hg red lines. 



TABLE 364. — Characteristics of Photoflash Lamp 

 (Forsythe, Earley, Journ. Opt. Soc. Amer., 21, 685, 1931.) 

 G. E. Photoflash lamp burns electrically ignited 65 mg Ai foil, .00004 cm thick in closed 

 glass bulb with excess of o 2 . 



Light output, 47,000 lumens, sec. f Max. intensity 4,500,000 lumens 



Light equals that of 100-watt Mazda for 37 sec. \Over 3,000,000 for 0.005 sec. 

 Flashes start in 0.01 sec. with no v. Flash lasts 0.066 sec. Time to max. 0.014 sec. 



TABLE 365.— Visibility of White Lights 



1 Paterson, Dudding. 2. Deutsche Seewarte. 

 Smithsonian Tables 



