1904] Atmospherical Radio-activity in High Latitudes. 215 



left for future investigation. Table III gives the relation between the 

 radio-activity and potential gradient. The mean potential gradient for 

 the period of each exposure having been taken with a self-registering 

 electrometer, the values of the radio-activity for each interval of 

 50 volts meter have been put together and the mean taken. 



Table III. — Eadio-activity and Potential Gradient, measured in Volts 



per Metre. 



No. of observations . 



Negative 

 pol. grad. 



0—50. 



50—100. 



100—150. 



150—200. 



6 

 33 



66 



3 



150 



168 



13 

 96 

 198 



17 

 140 



432 



8 



150 



384 







No. of observations. 



200—250. 



250—300. 



300—350. 



350—400. 



-100—450. 



4 

 96 

 144 



6 

 84 



144 



8 

 61 



138 



2 



111 



150 







3 

 83 

 150 







As can be seen, there is no direct relation between the radio-activity 

 and the potential gradient. 



To come now to the effect of the meteorological elements, Table IV 

 shows that temperature and radio-activity are not closely related. 



Table IV. — Radio-activity and Temperature. 



Temperature °C. . . 



-40° to 

 -30° 



-30° to 

 -20°. 



-20° to 

 -10°. 



-10° to 0°. 



0° to 10°. 



No. of observations . 



12 



10 



17 



25 



8 





127 



166 



80 



82 



110 





294 



432 



204 



174 



198 



Nor does the barometric pressure appear to have any great influence. 



Table V. — Radio-activity and Barometer. 





720—730. 



730—740. 



740—750. 



750—760. 



No. of observations . . . 



10 



18 



23 



20 





66 



109 



85 



137 





180 



29 % 



204 



432 



