90 Prof. Faraday on Electric Induction— 
instead of travelling wholly through it, though it be so excellent 
a conductor, will pass in large proportion throug 
the air at s, as a bright spark; for with sucha /[ \ 
length of wire, the resistance in it is accumulated 
until it becomes as much, or perhaps even more, 
than that of the air, for electricity of such high 
intensity. 
Admitting that such and similar experiments 
show that conduction through a wire is preceded 
by the act of induction (i338), then all the phe- 
nomena presented by the submerged or subterra- 
nean wires are explained ; and in their explana- : 
tion confirm, as I think, the principles given. 
After Mr. Wheatstone had, in 1834, measured 
the velocity of a wave of electricity through a m 
copper wire, and given it as 288,000 miles ina wl 
-second, I said, in 1838, upon the strength of these principles 
(1333), “that the velocity of discharge through the same w 
may be greatly varied, by attending to the circumstances which 
cause variations of discharge through spermaceti or sulphur. 
Thus, for instance, it must vary with the tension or intensity of 
the first urging force, which tension is charge and induction. So 
if the two ends of the wire in Professor Wheatstone’s exper 


a 
Leyden battery, then the retardation of that spark would be still 
3 | 
