Secondary Radiation. Secondary Radiation. 
114 Prof. Thomson , On Secondary Rontgen Radiation. 
w 
Pt 
PbBi 
Cdn 
b -Te 
x 
Ni 
CuZr 
Mo 
L 
nr. 
— f 
l 
c 
20 40 60 80 100 120 140 160 180 200 220 
Atomic Weights. 
Fig. 4. Soft Primary Rays. Plates 15 mms. apart. 
Fig. 5. Very soft Primary Rays. Plates 1 mm. apart. 
