206 



Profs. W. E. Ayrton and John Perry. [Mar. 21, 



Zero. Eeading. Deflection. 



1062 -8 1027 -8 35 -0 



62 -2 94 1 31 *9 



64 -9 31 '5 33 "4 



64 7 98 -0 33 '3 



62 -1 24 -5 37 -6 



Mean. ...... ..... 33 '8 



-5 of a Cell. 



1064 -0 1080 1 16 I 



64-6 45-8 . 18-8 



57 -1 70 -8 13 7 



57 -0 37 -5 19 -5 



Mean 17 '0 



It was not necessary to prove the law of proportionality for other 

 distances than 6*4 and 16 mm. 



Table IV.— 9th March, 1876. Plates 10 "9 mm. apart. 

 One Cell. 



Zero. Eeading. Deflection. 



1055 -5 1101 -5 46 -0 



57 -0 1006 -6 50 -4 



55 -8 1100 '6 44 -8 



56 -2 1005 -5 50 7 

 56 1 1100 -0 43 -9 

 55 -0 1002 -0 53 -0 



53 -4 1098 '5 45 '1 



54 -0 1004 -0 50 -0 



Mean 48 '0 



The Daniell was occasionally connected with the electrometer 

 directly. It constantly gave the deflection 2 30 '4. It was not a new 

 Daniell. Thus the ratio between the deflections obtained by two 

 methods of measuring a difference of potential, one by direct connexion 

 with, electrometer, and the other by reversing the induction plates, 

 is 3'4, when the distance between the plates is 6'4 mm., 4*8 for 10"9 

 mm., and 6'8 for 16*0 mm. Plotting three points on squared paper 

 with these numbers as co-ordinates, and drawing the arc of a circle 

 through them, we found the approximate values of the ratios cor- 

 responding with different distances given in Table V. This table was 



