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IV. 



THE ELECTEIC CHAEGE ON EAIN (Part II). 

 By PEOFESSOE J. A. McCLELLAND, D.Sc, F.E.S., 



AND 



J. J. NOLAN, M.A., M.Sc, University College, Dublin. 



Eead June 24. Published Septembku 13, 1912. 



The present paper deals with the continuation' of the work described in 

 an earlier paper. The previous observations were carried out during the 

 months of March, April, May, and June of 1911. The period was a rather 

 dry one, so that while the rain examined was of a very varied character, 

 the total amount was small. Observations were begun again towards the end 

 of October, 1911, and continued up to. the end of May, 1912. We have thus 

 been able to obtain a fair sample of the year's rainfall, with the exception 

 of the long-vacation interval. Part of the year, that is from March to June, 

 has been duplicated ; and while, as will be seen, the agreement between 

 the two sets of observations is generally good, it is especially good over this 

 particular interval. 



The apparatus and method of observation have been described in the 

 previous paper. Some minor replacements and alterations were made, but 

 the form and dimensions of the apparatus remain as before. The method of 

 direct personal observation as against any form of self-recording apparatus 

 has been retained. In the course of our observations of different types 

 of rain, we have found it necessary, in order to obtain accurate readings, 

 to increase the capacity of the electrometer system by amounts varying 

 from '001 to 1 micro-farad. It is clear that no ordinary form of self- 

 registering apparatus could give an adequate record of these widely different 

 types of rain. Something is gained also from an inspection of the character 

 of the rain, the size of tlie drops, and the conditions under which it occurs. 

 Except in one instance, no observations of potential gradient have been 



' Proc. Eoyal Irish Academy, vol. xxix., A. ?»o. 5, Febriiaiy, 1912. 

 B.I. A. PUgC, VOL, XXX., SECT. A. [10] 



