484i Messrs. G. C. Foster and 0. J. Lodge on the Flow of 



Case 2. Two equal electrodes, one at the centre and one on 

 the ed&'e of a circular disk . 



Number of 

 experiments. 



r. 



s. 



s—ex 

 P 



8 



7 



1316 

 7-62 



46-47 

 41-81 



2310 

 23-60 







Mean 



23 33 



Here L = 31og - by formula (21), § 39, Part I., and there- 



fore ^i =3Ce=23-33, whence 2C = 3'022. 

 log?: 



The lines of flow and of equal potential for this case are shown 

 in fig. 6, Plate X. Part I., by the part of the figure inside the 

 circle. This figure represents the case of two opposite poles in 

 an unlimited sheet, one of them being twice as strong as the 

 other. One of the flow-lines is then a circle passing through 

 the pole of double strength and having the other pole at its 

 centre. The remaining flow-lines lie half of them within this 

 circle and half of them outside. Consequently, if the sheet be 

 cut along the circumference of this circle (which in the figure is 

 shown as complete), a disk is obtained in which the electrical 

 conditions are the same as in this experiment. 



Case 3. Both electrodes in the disk, one on each side the centre 

 and at equal distances from it. 



Number of 

 experiments. 



r. 



AB. 



s. 



s — ex 



, 5.AB 



tog-s 



S.p 



4 

 5 



1316 

 762 



1316 

 762 



36-92 

 32-78 



16-20 

 1605 









Mean 



1612 



Here L becomes 2 lo£ -s- , whence 



— ex 



3. 



2C = 3-132. 



, 5.AB 



= 2Ce, and 



