350 
PROFESSOR C. RIVER OR THE 1RDUCTIOR OF ELECTRIC 
now 
S rp' rp o' \ „ I O ^T b+ i rp dS , i+1 
«+!-*-«+] « + l — + l -■ 
<7« 
■«+l 
<7* 
+ • • • 
= Xc. — ^r,+ terms negligible. 
ffffi__ , rfS„ 
S w+1 T'„-T ;i+1 Sb=S /i+1 T„-T„ +1 S„+\c S 
~A. 2 a 2 ^" ‘ ‘ ’ 
+ 
and it may be easily shown, by working out the different coefficients of c, c 2 , . . . , 
that the terms neglected are really negligible. 
Finally, we obtain 
putting a for b in (3. 
C + A 2n + l’ 
47rma)a 
(Ik) Here 
(2w + l)R 
C + A' 2n 4-1 /bV ' +1 ShT'n-i-ThSh-! 
A' 
Xa \a/ • S„ +1 T' li _ 1 — T ii+1 S / „_ 1 * 
■ • (29) 
The numerator is, as we know, ——; and the denominator 
Vb~ 
= S„ +1 T„_ 1 -T„ +1 S„_ 1 +Xc(s„ +1 ^i-T, i+1 ^) + 
the former of which set of terms 
2 n +1 
~cU ' 
rS«-i 
To find the latter we observe that 1 "~-f-S„, and similarly for T ; hence 
the term in \c is 
Xc r c»-i)( 2 »+i), i 
the first term of which is negligible compared to the second : putting these different 
results together, and making 
^bY (+1 
= 1 aud /3=a, 
C + A ' 
A' 
1 
o 
2?i+1 _ 
^ -I - 1 t \c 
+ 
i — 
Vac 
2n+l’ 
