Am. Jour. Sci., Vol. XL, 1890. 



Plate V. 



600 



S00— 1 



400- 



300- 



200- 



100— 



Four Curves of Equal Areas, showing one unit of heat displayed 

 successively in heat spectrum of Gas, Electric Arc, Sun and 

 Fire-Ply. 



Abscissae. — Wave Lengths. 

 Ordinates. — Energy as Heat. 



ENERGY CURVE. 



G-as Flame Spectrum. 

 MAXIMUM AT 1^6. 

 Fig-. 1. 



LIMITS 



OF 



VISIBLE 



SPECTRUM. 



500— 

 400— 

 300— 

 200— 

 100— 

 0— 



0A 0.6 0.1 



800- 

 700— 

 600— 

 600- 

 400— 

 300— 

 200— 

 100— 



400- 

 300— 

 200— 

 100— 

 



ENERGY CURVE. 



Electric Arc Spectrum. 



MAXIMUM AT 1?16. 



Fig-. 2. 



H 1 1 h 



H 1 1 1 



I.0 I.2 1.4 1.6 1.8 2.0 2.2 2,4- 2.6 2.8 3.0 



ENERGY CURVE. 



Solar Spectrum. 



MAXIMUM AT 0^62 



LIMITS 



or 



VISIBLE 

 SPECTRUM. 



Fig. 3. 



\Z 2.0 2.2 Z4 2.6 2.8 3.0 



ENERGY CURVE. 



Fire-Fly Spectrum. 

 MAXIMUM AT 0^57. 



Fig-. 4. 



:1 



— i 1 1 1 1 1 1 1 1 1 1 



0A 0.6 0.8 1.0 1.2 \A 1.6 1.8 20 22 2.4- 2.6 2.8 3.0 



