378 J. 31. Adams — Transmission of Rontgen Rays. 



to draw conclusions as to the constancy of any or all of the 

 separate coefficients from the constancy of the percentage 

 reduction is not in strictness possible ; it might be that two or 

 more of the coefficients changed together in such a way as to 

 keep the percentage reduction constant. The repetition of 

 this coincidence, however, in experiments with different metals 

 and with rays from tubes in very different conditions is 

 exceedingly unlikely, and the constancy of the percentage 

 reduction of deflection with varying intensity is at least very 

 good presumptive evidence that the coefficients characteristic 

 of the absorption of Rontgen rays in metallic sheets are all 

 constant with varying intensity of the rays. 



Jefferson Physical Laboratory, 

 Harvard University, Cambridge, Mass. 



