Prof. Thomson, On Secondary Rant yen Radiation. 113 
O zo 40 60 eo 100 izo 140 1 feo ieo zoo zzo 
ATOMIC WEIGHTS 
Fig. 2. — Hard Primary Pays. Plates 15 mms. apart. 
Atomic Weights. 
Fig. 8. Hard Primary Rays. Plates 1 mm. apart. 
