INDUCTION OF ELECTRIC CURRENTS. 
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wire was stretched in precisely similar forms on a second board, so that when 
brought near the first, the wires should everywhere touch, except that a sheet 
of thick paper was interposed. One of these wires was connected with the 
galvanometer, and the other with a voltaic battery. The first wire was then 
moved towards the second, and as it approached, the needle was deflected. 
Being then removed, the needle was deflected in the opposite direction. By 
first making the wires approach and then recede, simultaneously with the 
vibrations of the needle, the latter soon became very extensive ; but when the 
wires ceased to move from or towards each other, the galvanometer needle soon 
came to its usual position. 
19. As the wires approximated, the induced current was in the contrary 
direction to the inducing current. As the wires receded, the induced current 
was in the same direction as the inducing current. When the wires remained 
stationary, there was no induced current (54.). 
20. When a small voltaic arrangement was introduced into the circuit be- 
tween the galvanometer (10.) and its helix or wire, so as to cause a permanent 
deflection of 30° or 40°, and then the battery of one hundred pairs of plates 
connected with the inducing wire, there was an instantaneous action as before 
(11.) ; but the galvanometer-needle immediately resumed and retained its place 
unaltered, notwithstanding the continued contact of the inducing wire with 
the trough : such was the case in whichever way the contacts were made (33.). 
21. Hence it would appear that collateral currents, either in the same or in 
opposite directions, exert no permanent inducing power on each other, affecting 
their quantity or tension. 
22. I could obtain no evidence by the tongue, by spark, or by heating 
fine wire or charcoal, of the electricity passing through the wire under induc- 
tion ; neither could I obtain any chemical effects, though the contacts with 
metallic and other solutions were made and broken alternately with those of 
the battery, so that the second effect of induction should not oppose or neu- 
tralize the first (13. 16.). 
23. This deficiency of effect is not because the induced current of electricity 
cannot pass fluids, but probably because of its brief duration and feeble inten- 
sity ; for on introducing two large copper plates into the circuit on the in- 
duced side (20.), the plates being immersed in brine, but prevented from 
MDCCCXXXII. 
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