Some Spectral Luminosity Curves Obtained by Flicer and Equality of Brightness Photometers

In the present paper are given some results obtained in the progress of an extended investigation upon methods of heterochromatic photometry. The investigation is as yet far from completed and the results here presented form only a part of the work already done, and a smaller part of that yet to do. They form, however, a fairly complete investigation as they stand, and as they illustrate satisfactorily some of the chief phenomena appearing from the investigation in progress they are thought to be of sufficient interest to be presented now.