36S Prof. D. N. Mallik on 
and .\ 
3 <L t 1 P* ^ 
3A 3A 1 V 
p*+i 
pr+25+3 * l r+a+1' 
and accordingly, 
a_ i/iy /ay, ,1 
V ^ •p.+.+.S L\,o/ *+' +1 1.2 \p) "- r rf*+--J 
i£c. 3. Two concentric and coplanar elliptic wires. 
Describe coaxial spheroids of which the ellipses are parallel 
sections. 
Then if p is the distance between any two points of the 
spheroidal shells of which the given ellipses are plane 
sections, 
i = Js(2»+i)P.MP„(fOQ.W<W«') 
+ 1 222 g^^Tir wt;;v)q»' wot m«>s k*-*') 
where ftr, /ir' are the major axes of the elliptic areas, 
and 
--Mfc©*"- 
Remembering that pdn = h*rdr 9 
and jocfo = A s r (r 2 — 1) sin 6 d6 dcj> 
we get 
X cos m((f) — <j>') dcj)d(f)' ; 
