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THE ROYAL SOCIETY OF CANADA 



These results are plotted in fig. III. In fig. IV the mean deflection 

 per mm. for the different potentials across the qiiardants are plotted. 



10 20 



Dcfle-ction in mm. 



30 



The results show that the instrument has a high degree of sensitive- 

 ness and that it is constant within 5% over the range of the scale. 

 The error in taking the tangent instead of the arc is only 2%, but it is 

 necessary of course to calibrate the instrument for the particular po- 

 tentials that are used. 



