ADAMS. — TRANSMISSION OF IloNTGEN RAYS. 



681 



drawn, and the deflection produced by tlie unimpeded rays was observed, 

 for the purpose of making allowance for any small variation in the ac- 

 tivity of the tube. The ratio of each deflection obtained with a screen 

 interposed to the mean of these two standardizing deflections was com- 

 puted, and the relative deflection thus obtained was plotted as ordinate 



2 

 O 



(- 



o 



LU 

 _1 

 Li. 

 UJ 

 D 



Hi 



> 



Ul 



a: 



to 



.9 

 .8 

 .7 

 .6 

 .5 

 .4 

 .3 

 .2 

 J 



.001 .002 .003 .004 .006 -006 .007 .008 .008 .010 



THICKNESS 

 Figure 4. 



CM^ ■ 



This curve shows the relation between the deflections of the instrument and 

 the tliickness of the tinfoil screens interposed in the path of the rays. The 

 thickness, in centimeters is plotted as abscissa, and tlie correspondhifr " relative 

 deflection" (that is, the deflection observed when the screen is interposed divided 

 by the deflection observed when the screen is withdrawn) is plotted as ordinate. 

 It is to be noticed that each successive equal increment of thickness of the 

 screen is less effective in reducing the deflection than the one preceding it. 



against the thickness of the corresponding screen as abscissa. An ex- 

 periment of this kind on screens of tin is illustrated by Figure 4. The 

 tinfoil used was not much alloyed by lead, judging from its appearance 

 and from a measurement of its specific gravity. The curve is from 

 data taken January 9 with the tube at 20 cm. from the instrument. 

 A curve taken January 10, with the tube at 25 cm. distance, and 

 another curve taken on the latter day with the tube at 20 cm. distance, 

 coincide with this one so closely as to be indistinguishable from it. 

 Such exact reproduction of results on successive days was possible only 

 when the tube was comparatively new. 



