526 Eartli Penetrating Radiation on Land and Sea. 



of different days are given in Table II., and those taken at 

 different times at Bowland, Scotland, are given in Table III. 



Table II. 





Values of ' ; q '' obi 



ained at Cambridge. 





Date. 



Hour of the day. 



Value of q. 



Aug. 17 



3.30 p.m. 



9*22 ions per c.c 



per see. 



18 



5.30 p.m. 



9-52 





21 



6.00 p.m. 



8-8-1 





2"> 



fi.45 p.m. 



876 





28 



5.30 p.m. 



8-82 





Sept.. 1 



12 noon 



8-98 





o 



10.45 a.m. 



9-19 





4 



10.50 A.M. 



9-00 





5 



10.30 A.M. 



8-95 

 Mean 903 







Table III. 



Values of " q" obtained at Bowland, Scotland. 



Date. 



Hour of the day. 



Value of q. 



Sept. 14 



10 A.M. 



11 A.M. 



12 noon 



1 P.M. 



2.30 p.m. 



8 - 32 ions per c.c. per sec. 



8-32 



8-32 



8-32 



8-32 



Mean 8'32 



The readings given in Table II. it will be seen, with the 

 exception of that obtained on August 18th, vary by not more 

 than 3 per cent, from their mean value, while those given in 

 Table III. were the same, namely, 8'32 ions per c.c. per sec. 

 for measurements made between 10 o'clock in the morning 

 and half past two in the afternoon, the rate of movement of 

 the gold leaf in all five of these observations being constant. 

 In so far as these observations go, therefore, it seems certain 

 that variations in the intensity of the penetrating radiation at 

 the observation stations selected at Cambridge and in Scotland 

 do not exist in amount greater than 2 or at most 3 per 

 cent. 



