Page:Collected Physical Papers.djvu/75

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55
COLLECTED PHYSICAL PAPERS

the other case to the transmitted component. The receiver was made moderately sensitive, so that the deflections lay within the scale.

 Thickness of air for reflection.  Thickness of air for transmission.  Deflection produced.
  4  16  66
  6  14  70
  8  12  90
 10  10  120

When the thickness of air was reduced to 0·45 mm., a deflection of two divisions was obtained for the reflection reading. From this an approximate idea of the intensity of the reflected component may be obtained. From the table given above, it is seen that half the total radiation gave a deflection of 120 divisions. The intensity of the reflected component, with a thickness of 0·45 mm., is therefore 1/120th part of the total amount of incident radiation, on the assumption, which is only approximate, that the galvanometer deflections were symmetrical. When the thickness was reduced to 0·3 mm., no reflected component could be detected, though the receiver was made extremely sensitive.

(Proc. Roy. Soc., Nov. 1897.)