292 



Mr. Powell on Solar Light and Heat. 



[Oct. 



Bulb coated with black silk. 



\ inch outside. 

 5 inch 



| inch 



1 inch, and nearer lens. 



10° 



8 

 7 

 5 



(56.) I now proceed to the later series of experiments : — 



Lens, focal distance 7-5 inches. Aperture reduced to 1 inch. Distance from lens 

 7 # 5 inches. Bulb just without the cone of rays. 



Exp. 



Focus thrown be- 

 tween the bulbs. 



53 52 



52 



44 45 



Both bulbs away, 

 and under shadow. 



50 



45 46 



44 



Black bulb nearest 

 the rays. 



49 50 



44 45 



47 



Plain bulb 

 nearest. 



46 45 



41 42 



44 



8 







10 



No case. Aperture 3*5 inch. 



Both bulbs away. 



26 

 30 



Black nearest. 



27 



27 



31 30 



Other bulb nearest. In 

 part coated with brown 

 silk. 



22 



20 17 



18 



11 



Both bulbs awav. 



12 



36 J4 



Aperture 1 inch. 

 Black bulb nearest. 



39 10 38 



Plain bulb nearest. 



32 



