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[162]. Rutherford and Miss Brooks, Phil. Mag. July, 1900.
[163]. Since the ionization at any point above the plate is the resultant effect of the α particles coming from all points of the large radio-active layer, λ is not the same as the coefficient of absorption of the rays from a point source. It will however be proportional to it. For this reason λ is called the “absorption constant.”
[164]. Townsend, Phil. Mag. Feb. 1901.
[165]. Durack, Phil. Mag. July 1902, May 1903.
[166]. Bragg and Bragg and Kleeman, Phil. Mag. Dec. 1904.
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