Proceedings of the Royal Irish Academy. 



total number could with certainty be divided into the large and small classes. 

 The apparatus for small ion work described in the previous paper was used. 

 The results of all the observations are shown in the following table : — 



Table. 



Date 



(JV+ n)+ 



n + 



n — 



X + 



Remarks. 



1912 

 Dec. 17, 



1430 















Strong S.W. wind. 



„ is, 



2000 



— 



- 



— 



W. to S.W. wind. 



,, 19, 



2960 



— 



— 



— 



Clear day; light W.S.W. wind. 



1913 

 Jan. 4, 



< 300 



— 



— 



— 



S. to S.W. wind. 



„ ', 



1150 



— 



— 



— 



S.W. wind. 



., 9, 



300 



— 



— 



— 



After rain and storm S. wind. 



,, 12, 



3800 



_ 



— 



- \ 



Light wind from Dublin ; fine frosty day. 



„ 12, 

 „ 12, 



10600 

 7600 









:j 



Limits of a number of observations during two 

 hours, 3800 to 10600. Mean 7600. 



,. 13, 



1600 



1380 



— 



220 



S.W. wind. 



„ H, 



700 



600 



— 



100 



S.E. wind. 



,, 15, 



1400 



300 



— 



1100 



S.W. wind. 



„ 24, 



900 



600 



600 



300 



S.W. wind. 



„ 26, 



1550 



200 



— 



1350 



S.W. wind. 



,, 27. 



1670 



340 



— 



1330 



S.E. wind. 



,, 28, 



— 



300 







— 



S. wind. 



., 29, 



— 



700 







— 



S. to S.W. wind. 



Feb. 5, 



1500 



250 



350 



1250 



S.W. wind. 



„ ': 



1520 



1180 



1360 



310 



S.W. wind. 



„ 10, 



1230 



220 



210 



1010 



S.W. wind. 



„ 12, 



700 



290 



280 



410 



S.E. wind after disappearance of thick fog. 



„ 13, 



5770 



70 



80 



5700 



S.E. wind, very thick fog. 8.15 p.m. 



„ 16, 



1080 



460 



410 



620 



E. to X.E. -wind. 



,, 17, 



2700 



2500 



2500 



200 



Strong E. wind. 



The Large Ions. 

 It will be seen immediately that only on two occasions, namely, on 

 January 12th and February 13th, do the number of large ions approach the 

 values obtained in Dublin. The mean of the values of iV when this quantity 



