410 



KNOBLAUCH ON RADIANT HEAT. 



Taule XXXIX. 



It is thus seen that e. g. the rays of heat reflected by silver 

 and sheet iron, which directly deflected the needle 13°, produce 

 a deviation of 8°'39 to 8°*43 on transmission through the red 

 glass, or of 15°-50 to 15°-56 when transmitted by the plate of 

 calcareous spar, the direct deflection amounting to 25°. The 

 heat reflected by white oil-paint, as also that by black lac, pass 

 through red glass or calcareous spar in the same proportion ; for 

 in the former instance a recess of the needle from 13° to 8°*37- 

 8°'62 occurs with both ; in the second, from 25° to 20°-94-20°-88. 



Table XL. 



Neither do we here find any difference in the transmission of 

 the heat reflected by the bodies which are compared; for the 

 needle recedes from 13° to 7° on the insertion of the red glass; 

 and on introducing the calcareous spar, from 20° to 10°"63-10°*5, 

 whether the heat of the red-hot platinum is unreflected or dif- 

 fusely reflected by silver or sheet iron. The rays reflected by 

 white oil-paint and black lac, which produced a direct deflection 

 of 13", caused the needle to deviate 8°*5 on transmission through 

 red glass ; and when the direct deflection was 20°, on transmis- 

 sion through calcareous spar, produced a deviation of 12°"25 to 



