ADAMS. 



TRANSMISSION OF RONTGEN RAYS. 



677 



on. The distances used were such that the lamp could be considered 

 as a point source, and hence the constancy of the product 



deflection X square of distance 



is proof of the proportionality in question. The maximum deflection 

 was used rather than the steady deflection, in this work and in all the 



TABLE I. 

 Relation of Dkflkction to Energy absorbed. 



work of this paper, because of the drift and other disturbances which 

 rendered inaccurate the determination of the steady deflection. A 

 specimen set of readings is given in Table I. By d is indicated the 

 distance from the lamp to the platinum of the instrument, in meters, 

 A calibration of the instrument in absolute measure was next made. 



