MKKCl IJY STANDARDS OF RESISTANCE, ETC. y.3 



Thus in the figure (fig. 14), if ( )( ! and OD be the axes, and p the platinum Ir.-ul 

 dipping into the mercury, then, supposing the tube to be symmetrical with respect to 

 tin- sect inn, the potential of p will IK? the same as that of , and therefore of A 

 where A lies mi the e<|ui|xitentiul .surface passing through n. It', m>\\, the two tubes 



IP 



be rotated through 180, the potential of p will, for the same reasons, l>e that of B. 

 It is evident that if the displacement of the axes is considerable, the error is liable to 

 l>e very great. This adjustment, therefore, is of the greatest importance, and much 

 care and practice are required to attain success. The details of the adjustment have 

 already l>een indicated. 



The following table summarises the measurements of resistance for this mode of 

 erecting the tubes. For comparison purjjoses, measurements by the Kelvin double- 

 bridge and the j>otentiometer are given together. Each horizontal line represents a 

 separate tilling of the tube : 



