Fig. 4. Penetrating radiation apparatus No. 1 (PR 1) ior measurement of ionization due to 

 cosmic rays and other penetrating radiations 



Fig. 5. Ionization apparatus of radioactive -content apparatus No. 4 (RCA4). Copper foil with a 

 deposit of radioactive material Is placed in this apparatus and the resulting ionization meas- 

 ured 



22 



