30 



THE ROYAL SOCIETY OF CANADA 



Figure 2 



These serve to exhibit the constancy of the ionisation produced by the 

 penetrating rays at the point of observation for a period of time extend- 

 ing over eight hours. 



III. Measurements on the Atlantic Ocean. 



The readings taken on the two voyages referred to above are given 

 in Table II. 



TABLE II. 



Measurements on the ionisation in a closed vessel taken on a steamer on the Atlantic 

 Ocean with a Wulf electrometer. 



Voyage No. I., on SS. Hesperian. 



Sept. 14, 1912 Firth of Clyde 4-4 ions per cc. per sec. 



15, " On the Ocean 4-2 



" " " 4-5 



" " " 4-1 



" " " 4-3 



" " " 4-3 



Off Belle Isle 41 



21, " Off Romouski 40 



22, " River St. Lawrence, near Quebec.4- 5 



16, 

 17, 



18, 

 19, 

 20, 



Mean 4-3 



ions per cc. per sec. 



