A New Experimental Determination of the Brightness of a Black Body, and of the Mechanical Equivalent of Light

Vision; general phenomena.

“…Hyde, Forsythe and Cady (56) present a new experimental determination of the brightnesses of a black body at temperatures between 1700 and 2600 0 K. The empirically obtained values agree well with those computed from the visibility data previously published by the same investigators and based upon direct comparison rather than flicker photometry. The same data also provide the basis for a new estimation of the mechanical equivalent of light as 0.00150 watts per lumen.…”

The nature of animal light

“…One candle-power emits 47r lumens. The latest figure for the mechanical equivalent of light at A = .566 is .0015 watt (Hyde, Forsyth and Cady, 1919), i.e., 1 lumen = .0015 watt. One watt is 10^e rgs (one joule) per second.…”

The nature of animal light

“…One candle-power emits 4ir lumens. The latest figure for the mechanical equivalent of light at A = .566 is .0015 watt (Hyde, Forsyth and Cady, 1919), i.e., 1 lumen = .0015 watt. One watt is 10^ergs (one joule) per second.…”