Mr. A. Schuster's Electrical Notes. Yd 



violates that condition at the origin. For the current func- 

 tion <t> = -5 represents the limiting case of a source and sink 



which are indefinitely approached to each other. If the 

 source and sink are joined together by the linear current 

 necessary to complete the circuit, the proper solution of the 

 question may be obtained. 



Take a system of currents due to a sink of electricity at A 



of strength \nr having a current function — , a source of 



strength 47r at B having a current function — — , and a linear 



current equal in intensity to \nr joining A and B. The value 

 of F' in that case would be 



when the last integral is to be taken over the line joining A 

 and B. The integration gives 



ds 



Vi >' 2 / J r 



If A and B approach each other indefinitely, 



x l —x 2 -=ds ; 

 and 



dx\r/ t \r r / 



the current function at the same time becomes 



x ds 



#=- 



x 



Corresponding to a current function <j)= —, we obtain therefore 

 the values 



• (10) 



These equations differ from those obtained before (9) by a 

 quantity representing the effect of an indefinitely short 



t—K 1 



+ 









> 









