664, 



Dr. A. S. Eve on the Effect of 



A systematic series of similar measurements was, therefore, 

 begun and continued for more than a month, whence the 

 results in the table following : — 



Table I. 





Divisions 



a minute. 











+ to 

 centre. 



- to 



centre. 



Eatio 



Humidity. 



Remarks. 



Sept. 25... 



20-0 



20'0? 



100? 



66 



N., clear after rain. 



„ 27... 



in 8 



14-0 



1-13 



95 



N.E., rain, misty. 



„ 28... 



181 



15-8 



1-15 



95 



W., heavy rain. 



Oct. 9 ... 



121 



11-2 



1-08 



76 



S. wind, smoky, misty. 



„ 11 .. 



16-7 



160 



1-04 



65 



S. wind, clearer. 



„ 12 ... 



16-8 



146 



1-15 



72 



Morning S.W., misty. 





18-6 



179 



1-04 





Afternoon, clearing. 



„ *13 ... 



18-8 



169 



1-11 



73 



S.W. 



„ 14'... 



17-5 



14-5 



1-20 



54 



s.w. 



„ 16 ... 



197 



18-5 



1-06 



86 



W., clear. 



„ 18 ... 



200 



19-1 



1-04 



77 



S.W., clear. 





(180 



160 



1-12 





Smoking in room.) 



... 



(13-6 



222 



111 



... 



Bun sen flame also.) 





(12-8 



111 



1-15 





Kettle boiling freely also.) 



„ "l9 ... 



192 



17-9 



1-07 



67 



N.W. 



„ 20 ... 



18 9 



174 



1-08 



65 



S.W. 





(9-0 



7-0 



1-28 



... 



Kettle boiling over Bunsen.) 



21 



133 



11-8 



1-13 



85 



Very smoky and misty. 



„ 22 ... 



14-6 



138 



106 



95 



S.W., clearer after rain. 



„ 23 ... 



189 



170 



1-11 



82 



W. 



„ 26 ... 



14-4 



11-5 



1-24 



88 



S.W. wind, smoky, misty. 



„ 30 ... 



21-1 



190 



1-11 



70 



S.W., very clear. 



Nov. 2 ... 



15-0 



14-2 



11)6 



92 



S.W., misty, a little rain. 



„ 3 ... 



18-2 



17-2 



106 



85 



S.W. 







Mean... 



1-10 







Each reading is the mean of about six readings, taken in a 

 room about 7x4x5 m. 3 with the windows open. 



The ratio n + jn— is a very variable and complex number, 

 and its magnitude may be dependent on humidity, dust, 

 smoke, electric force, intensity of ionization, diffusion, and 

 type of apparatus employed. Moreover, it is hard to measure, 

 because it is the ratio of two quantities each of which is 

 variable. 



It is clear, however, from the results in Table I., that with 

 a constant ionizing source at V and with a constant air 

 current, the ionization current in B varies greatly with the 

 type of atmospheric conditions* 



