The approximate efficiencies of a number of light-sources is calculated in table 1 by multiplying the mechanical equivalent of light (680) by successively ao the total radiation efficiency, be the fraction thereof falling in the visible region, and Co the average eye-sensitivity for this radiation in the visible regiono The light-sources mentioned in table 1 are: 10 a black body in vacuum, b. a gasfilled tungsten incandescent lamp, 3° a tungsten incandescent lamp with iodine addition, 40 a fluorescent low pressure merolamp, 5 ao sodium lamp with detachable outer jacket, 60 an integral sodium lamp, 7° an integral sodium lamp with an infrared reflecting film of tinoxide on the inside of the outer bulb, 80a high pressure mercuxy lamp and 9° a high pressure mercury lamp with additions of sodium-thallium.
Abstract