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Transactions of the Royal Canadian Institute 



The arrangement of apparatus was therefore changed to that given 

 in Fig. 2. ' 



Fig. 2 



A is the low resistance side of a Kelvin-Varley SHde Potentiometer 

 consisting of 100 twenty ohm coils. 



B is a plug resistance-box, from which a small resistance is taken to 

 allow of adjustment between the twenty ohm steps of the Slide. 



C and C are two guard-ring condensers made up of glass plates, 

 coated with tinfoil. The upper plate of each is connected to terminal (l) 

 In the tinfoil of the lower plate is cut a circular part connected to ter- 

 minal (2). The ring around it is connected to terminal (3). The two 

 plates are kept apart by means of small distance-pieces of glass or other 

 material, whose thickness is accurately measured. C rests on a table; 

 C is suspended from the ceiling by a rope, and after calibration of the 

 bridge, it is replaced by the capacity to be measured. 



Ci and Ci' are two adjustable parallel plate condensers, of which Ci' 

 is provided with a micrometer screw for close adjustment. 



K is a two-way key, and T a 5,000 ohm Baldwin telephone. 



The junctions of a resistance arm and a capacity arm are connected 

 to a Vreeland Oscillator. 



The leads from the Vreeland Oscillator and the telephone leads are 

 shielded by earthed metallic sheaths. The movable contact of the Slide 



