526 



Mr. J. Larrnor. 



'M.-.v M. 



ldrdf 

 rdsd*' 



d*ds 



_ f f 7 j / / & r dr dr 1 dtir dr 1 dr dcr d*e(r<j>r) 

 Jj ' \~i* ds cb'~r ~ds ds'~rdt ~di ds da ~ 



fi * I* /j ' I dr f i ,*' j , 1 dr 



= - \\&r\ t'dsi- - \\tr\ dsi- 



J I "% rMy V r da 



wv 



This variation is accounted for- by the following forces of repulsion, 

 tending to increase r. 



(i) Between the elements ids and ids', equal. to 



, , , / 1 Jr dr 2 (Fr 

 f<fo ( ____ J . + _- r ^_ 



\ r 2 a* os r dsdn 



or 



' 



Zids ids' >{cos e | cos ^ cos 0'), Ampere's law. 

 3 



(ii) Between, the element ufe. and the positive end of the con- 

 ductor de' t 



, ,1 dr 



, tdn - , 

 r o 



or 



, de 1 , , , 



ids cos (r . ds), 



dt r 



where dc' fdt is the rate at which the charge at that end is increasing, 

 (iii) Between the element: ids' and the end of the conductor ds, 



, , , I dr 



t (IS I ;, 



r dg" 



or 



t'ds'- I cos (r. d"), 



r being here measured away from ds'. 



(iv) Between an end of one conductor and an end of another con- 

 ductor, 



or 



dede 



' dt dt 



(1-0'r). 



