T 



456 Journal of the Asiatic Society of Bengal. [Jnlj, 1907^ 



and OjL €^ — ac= cX 



(' ^ f). 



Oo = - 27rm-l I 1 + 





nearly . 



14. If now 3f be the magnetic induction at any point of the- 

 surface, 



^ Ail— r° "SB 1 V^-lB'^^-lEJ^-^'^^^ 



(l + 47r;^)i) r^ ^Qo , <cj^" 



h^B I " (?E " dB 



dB 

 1 + 



A. 1 '^^^ 



(l + 47rA-) 



i'^CM) 



Q„(E) di? ^ ^ dii: ) 



(i+ir^l — ° + S0„ ^- 



. KI"-«"§)-.« 





But Qn{r)^\ Pn log - P..1 - . . . 



— ^ . loo* :^-^ - I -r . — I — + + 



dr dr ' ° r — 1 r* — 1 L 1 . n " dr 



-I 



* (ir ^ dr ~ r* — 1 L ^ • *** V <^^ ^dr) 



when r = E = 1, very nearly, the left-hand side is = a very large- 



negative quantity = - — — - very nearly. 



and /. Q„ —^ is large compared -R^ith -— ^ . 



dix dh; 



