L'Sl 



CAPTAIN W. DE W. ABNEV ON THE COLOUR 



of the curves, and how they approach in some respects those of KCENIG'S, of which 

 lig. 9 is a rough representation taken from one of his diagrams. There is n marked 

 difference, however, in the amount of red shown as existing in the violet. Whatever 

 source of light is taken as the standard the same proportion will exist. 



Fig. 8 



Sensation curves (normal spectrum) in which equal heights of ordinates form white (electric li ht crater). 



Fig. 9. 



H 



(XXIV.) Observation applied to the Solar Spectrum. 



One more example may be given. The sun's spectrum in the month of September, 

 at noon, was measured several years ago, and this has been divided up into lumi- 

 nosities. It is very similar in characteristics to the electric light spectrum. The 

 equation to the white light derived from the areas is 



RS GS BS W 



6573 + 33-83 + '44 = 100. 



