McCieLLaAnp— On Secondary Radiation. 179 
The results are as follows :— 
Primary Rays. Secondary Rays. 
Sheets of Foil. HP | 
Each 013 mm. thick. Tintolls26 GUN Tinfoil at Tinfoil at 
Ionisation Tube 7. Ionisation Tube 7’. | Ionisation Tube 7. 
7 haiagr 
| No foil . : : ‘ 100 | 100 100 
1 ey eee D 60 | 96 as 
| 
2 ALS eee ae 47 | 90 80 
4 ; j : ; 39 | UU 64 
8 ‘ : : : 32 | 66 44 
| 16 Meech ce 27 | 49 26 
32 : A : ; 22 eee 35 9 
Curve A, fig. 5, refers to the primary rays when the absorbing tinfoil is placed 
26 cms. from the ionisation tube; curve A’ to the primary rays, with the foil 
Cone eee 
i sueiasatasctf tose | 
mle 
ARABS (oa esi ee 
SEEN 
COSC See | 
Ss tons or taranpiaateee 
aan= Ce 
7aN 
‘(PRiMARy) 
“| [eae | 
al ae =~ < 23agee Primary) 
Seeconeeeee co 
ne Siew — : 
CCAS eae eee ees B (Seconpary) 
Jee eee Sea ese ae 
HTGamos 
INTENSITY OF RADIATION 
8 
placed close to the ionisation tube; curve B to the secondary rays. Curves A 
