M'Clkli.ani) and (iii.MoUK — 'Pk': Electric Chanjc on Rain. 2:] 



N&jalivc liain. 











C 



inr 



\t in Arnpores x 10'^. 





Month 







< 1 







1-5 





> 5 



J^niuiiy (No. c 



f Ol.s 



■)• 



10 

















Fcbruiiry, 



,, 





1-2 







1 









11 arch, 



,, 





7C 







7 





2 



April, 



„ 













2 





2 



May, 







13 

















June, 







3 







2 









July, 



,, 





150 







3 





2 



August, 



" 





23 







S 





1 



Totals, 



289 







23 



10 



The values contained in the above tables are possibly slightly too low, 

 owing to the fact that the zinc cylinder surrounding the receiver may be 

 expected to ward off a small portion of the rainfall from it. As the small 

 quadrangle in which the apparatus was placed is almost completely sur- 

 rounded by high buildings, the apparatus was well protected from the winds, 

 and this error is probably very small. 



The tables give a striking illustration of the fact that in non- thunderstorm 

 rain as well as in thunderstorm rain, investigated by Simpson,^ " the greater 

 the current the more likely is it to be carried by positively charged rain." 



Uncharged rain was never found during the observations. It was always 

 necessary to use a capacity of at least -001 microfarads on the electrometer, 

 so that the charge per c.c. on the rain was always greater than '00007 E.S.U., 

 the lowest that could be measured with this capacity. As a matter of fact, 

 a charge per c.c. less than twenty times this was exceedingly rare. 



The amount of positive electricity brought down was 3691-4 E.S.U., while 

 the amount of negative electricity was 702-9 E.S.U., so that 84 per cent, of 

 the total electricity brought down by the rain was positive. 



Thunderstorm Bain, 



Only two thunderstorms occurred during the time these observations 

 were being taken. Both took place late in the evening. The first was on 



Simpson, Phil. Traus. A, vol. ccix. 1909. 



