Effect of Electrical Convection. 



199 



disks, coil I, and coil T remained fixed throughout the 

 experiment. 



It was found that the values of p for any one coil in 

 corresponding positions on the two disks were very nearly 

 the same, within about one per cent.; thus showing that the 

 two sides of the apparatus were very nearly symmetrical 

 with respect to the coil. The values for the two sides of the 

 same disk differed about 5 per cent. The mean of the ratio 

 for the four positions of each coil was then plotted as 

 ordinates to the radii of the coils as abscissae. The curve 



2 KM 



thus found represents — -r — < Multiplying the ordinate of 



A 

 abscissa, 



each point by its 



— - — . The area of this from R L 



we get a curve representing 



, . 2K 



to xw is — — 

 A 



The value of 2 ^M R , 



r 



Mrdi 



is also given from the 



log. (2 cos g)}. 



Call this p. 



first curve. Call this v. Then 

 4ttKA f vB 



Two independent " calibrations " of the disk apparatus 

 were thus made, the first after set 7, the second after set 17. 

 Table I. gives the radii of the coils, the corresponding values 

 of p for each calibration, and the mean of the two sets. 



Table I. 



Eadii. 



Pi- 



p.,. 



Mean p. 



439 



•140 



•143 



•145 



5-98 



•284 





•284 



7 87 



•505 



•504 



•505 



904 



•(578 



•682 



•680 



10-02 



•845 



•848 



•847 



110.3 



1071 



1070 



1071 



1200 



1293 



1294 



1-294 



1282 



1 522 



1-501 



1-512 



1357 



1-092 



1697 



1695 



14-34 



1-880 



1-885 



1-883 



1521 



2-036 



2065 



2 051 



15-91) 



2-159 



2162 



2161 



The factor A is equal to the deflexion of the galvanometer 

 due to the current, commutated, induced in the coil I on 

 reversing a unit current in the coil T, as above described. 



