22 



I'rocefidliiyn nj the Ro>/al Iriah Aemfenli/. 



The above tables would seem to show that in the case of positive rain 

 the highest charge per c.c. occurs with rather heavy rain, the maximum 

 appearing fairly generally in tlie table when the rate of fall is from '6 to 

 1 mm. per hour. The following table gives the rate of fall corresponding to 

 times of discharge of tipping-bucket : — 



Time to tip bucket in niins. 



1' 



2' 



1 1 

 3" 4' 5' 6' 



Equivnlent rate of fall ( .,.. . .,. 

 in mm. per hour. ) " "* i "" 



1 



•83 -625 



•5 



■42 



With negative rain the light rain seems ic be most heavily charged, but 

 observations on it are le.sy numerous, and therefore not so reliable, since a 

 very few high values make a great diflerence in the totals, as in second 

 column in table. 



It seems to be customary, in pai)ers on the electricity of rain, to express 

 the ciiarge brought down as curront per square cm. of the earth's surface. 



Positive i2f«7i. 



Month. 



Current in Amperes x I0-" per sq. cm. 

 < 1 1-5 1 > •'>. 



JonuBrjr (No. 



of Ob..), 



43 



95 



13 



February, 





79 



106 



8 



March, 





72 



24 



3 



April, 





5 



9 



2 



May. 





8 







1 



June, 





21 











July. 





7 



6 



7 



Auguat, 



• 



130 



200 



24 



Totals 



375 



439 



68 



