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RO^AL SOCIETY OF CANADA 



shown in Fig. 1, and supported on ebonite blocks so as not to be in 

 electrical connection with the instrument proper. The receiver was then 

 charged to any desired voltage and the current through the air observed 

 by Ûie charge which was communicated in a given time to the electrode 

 carried by tlie gold leaf system. 



The function of the compensator C, which consisted of a sliding 

 tube condenser was to annul by its moliou any charge the system acquired 



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FIG. I 



through the conductivity of the air in the receiver; this motion being 

 so regulated as to keep the potential of the gold leaf always at zero, 

 and thus minimize any tendency to promote a leak across the quartz 

 insulation. 



Thus, for a determination of " q." it was necessary only to know 

 the charge annulled in the time during which the compensator moved 

 a standard distance. 



^ 



FIG. n 



For a determination of the charge corresponding to this standard 

 distance the parallel plate condenser shown in Fig. 2 was added in 

 place of the electrode. The compensator tube was then charged to a 

 known potential, giving for the total motion a certain deflection of 

 the gold leaf; and the voltage on the upper condenser plate was then 

 so adjusted as to bring the gold leaf back to its zero position. The 

 charge could then be readily calculated from the dimensions of the 

 parallel plate condenser and the voltage applied to it. 



