22 Air Oriffiths and Mr Clark, On the rise in resistance [Nov. 28, 



within the range of the thermometer {E) used in the calorimeter, 

 the calorimeter was then cooled down and allowed to heat up 

 until the low resistance galvanometer G^ showed no deflection, 

 the temperature being read at the same moment. This was 

 done in each case whilst the difference of potential at the ends 

 of the coil was increased from 1 to 6 Clark cells : since the re- 

 sistances of AD . AG bore a constant ratio, and the resistance 

 BD remained unchanged, the resistance of the arm BG, the coil, 

 must also be the same whenever balance is obtained, hence the 

 difference in the observed temperatures gave the number of 

 degrees that the wire was hotter than the water with which it 

 was in contact ; or since the temperature coefficient of the wire 

 had been determined [with E = '04 volts] the results could be 

 expressed in terms of increase in resistance. 



The following table gives the results of a series of observations 

 taken on Sept. 20, 1892. 



In order to find the value of x these numbers were plotted 

 with E.M.F. as abscissa and SB as ordinate, when they were found 

 to agree with the parabola 



ZR = -0042 E;' = -00204 E^ = -1575 G\ 



(where Ec is the E.m.F. of 1 Clark cell) within the limits of ex- 

 perimental error. 



From the form of this result, it would appear that the state- 

 ment 



BR = aG' 



