—688 Prof. Faraday on Electric Induction— 
in the sea, exhibit the same phenomena as those described, the 
like static inductive action being in all these cases permitted by 
the conditions. Such subterraneous wires exist between London 
and Manchester; and when they are all connected together so as’ 
to make one series, offer above 1500 miles; which, as the dupli- 
cations return to London, can be observed one experimenter 
at intervals of about 400 miles, by the introduction of galvan- 
ometers at these returns. This wire, or the half or fourth of it, 
presented all the phenomena already described ; the only differ- 
ence was, that as the insulation was not so perfect, the charg 
condition fell more rapidly. Consider 750 miles of the wire.in 
one length, a galvanometer a being at the beginning of the wire, 
a second galvanometer 6 in the middle, and a third c at the end; 
these three galvanometers being in the room with the experi 
menter, and the third ¢ perfectly connected with the earth. On 
bringing the pole of the battery into contact with the wire 
through the galvanometer a, that instrument was instantly affec- 
ted; after a sensible time 5 was affected, and after a still longer 
time ¢: when the whole 1500 miles were included, it required 
two seconds for the electric stream to reach the last instrument. 
Again; all the instruments being deflected (of course not equally, 
because of the electric leakage along the line), if the battery 
were cut off at a, that instrument instantly fell to zero; but > 
did not fall until a little while after; and ¢ only after a still lon 
ger interval,—a current flowing on to the end of the wire whilst 
there was none flowing in at the beginning. Again; by as 
touch of the battery pole against a, it could be deflected and 
could fall back into its neutral condition before the electrl¢ 
wer had reached 6; which in its tarn would be for an instant 
affected, and then left neutral before the power had reached ¢; 4 
wave of force having been sent into the wire which gradually 
travelled along it, and made itself evident at successive interv 
of time in different parts of the wire. It was even possible, bY 
adjusted touches of the battery, to have two simultaneous waves 
in the wire following each other, so that at the same mom 
that ¢ was affected by the first wave, a or 6 was affected by the 
second; and there is no doubt that by the multiplication of i 
struments and close attention, four or five waves might be 0 
tained at once. al 
after making and breaking battery contact at a, a be imme 
diately connected with the earth, then additional interesting ef- 
fects occur. Part of the electricity which is in the wire will f& 
turn, and passing through a will deflect it in the reverse direc 
tion; so that currents will flow out of both extremities of the 
wire in opposite directions, whilst no current is going into it from 
any source. Or if @ be quickly put to the battery and then 
the earth, it will show a current first entering into the wire, 
