------------------------+------------------------+--------+---------------- | | |Efficiency Illuminant and | Commercial | Lumens |(visible commercial description | rating | per |radiation × | | watt |visual | | |sensibility ÷ | | |total radiation) ------------------------+------------------------+--------+---------------- Carbon incandescent lamp| 4 watts per mean | 2.6 | 0.0042 oval anchored (treated)| horiz. c. | | filament | | | | | | Tungsten incandescent | 1.25 watts per mean | 8.0 | .013 lamp, vacuum type | horiz. c. | | | | | Mazda, type c | 600 C. P. 20 amp., | 19.6 | .032 | 0.5 w. p. c. Series | | | type C. | | | | | Carbon arc (open) | 9.6 amp. clear globe | 11.8 | .019 | | | Open arc, yellow flame, | 10 amp. D. C. | 44.7 | .072 inclined trim | | | | | | Quartz mercury arc | 174-197 volt, 4.2 amp. | 42.0 | .068 | | | Glass mercury arc | 40-70 volt, 3.5 amp. | 23.0 | .037 | | | Nernst lamp | | 4.8 | .0077 | | | Acetylene | 1 L per hr. consumption| .67 | .0011 | | | Petroleum lamp | | .26 | .0004 | | | Open flame gas burner | Bray 6 high pressure | .22 | .00036 | | | Incandescent gas lamp, | .350 lumens per | 1.2 | .0019 low pressure | B. T. U. per hr. | | | | | Incandescent gas lamp, | .578 lumens per | 2.0 | .0032 high pressure | B. T. U. per hr. | | | | | Firefly | | 629.0 | .96 ------------------------+------------------------+--------+----------------