Lengthening of the Spark from an Induction-Coil. 487 
Thus approximately when 2 is great 
2 Lot ae 7 eh aang 
JJ Ve dy=y | ik +P B/Qike) | - 
sare 4 
ei ee i) Shona) ity) s (16) 
if we confine ourselves to the leading real and imaginary 
terms. 
From (2) we now get 
+ 2 jhaGed Ri a9 2 
J \ 8p ds= : ce 1 Tis ot 
T dn j 
dé ity 26), 
. VY. —- 17 
at “J ak?x dt? — 
When wz is large, the inertia term ultimately vanishes in 
comparison with the area of the plate. The reaction is then 
reduced to the dissipative term, which is the same as would 
be obtained from the theory of plane waves of infinite 
extent. 
-+ 
= Ly .ao 
XLVII. On the Lengthening of the Spark from an Induction- 
Coil by the Aid of Auxiliary Wires. By T. J. BowLKER*, 
[* a discharge is taking place between the ends of two 
wires connected with the poles of an induction-coil, the 
ends of the wires being at such a distance that the spark just 
passes freely, then if an insulated wire be so placed that one 
end is near the positive terminal, and some other point on the 
Fic. 1, 
wire is almost touching the wire leading to the positive 
terminal, the length of the spark is greatly increased 
(see fig. 1). 
* Communicated by the Author. 
