132 MR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. 
30. When the battery contact was made in one direction, the galvanometer 
needle was deflected on the one side ; if made in the other direction, the de- 
flection was on the other side. The deflection on breaking the battery contact 
was always the reverse of that produced by completing it. The deflection on 
making a battery contact always indicated an induced current in the opposite 
direction to that from the battery ; but on breaking the contact the deflection 
indicated an induced current in the same direction as that of the battery. No 
making or breaking of the contact at B side, or in any part of the galvanometer 
circuit, produced any effect at the galvanometer. No continuance of the bat- 
tery current caused any deflection of the galvanometer-needle. As the above 
results are common to all these experiments, and to similar ones with ordinary 
magnets to be hereafter detailed, they need not be again particularly described. 
31. Upon using the power of one hundred pair of plates (10.) with this ring, 
the impulse at the galvanometer, when contact was completed or broken, was 
so great as to make the needle spin round rapidly four or five times before the 
air and terrestrial magnetism could reduce its motion to mere oscillation. 
32. By using charcoal at the ends of the B helix, a minute spark could 
be perceived when the contact of the battery with A was completed. This 
spark could not be due to any diversion of a part of the current of the bat- 
tery through the iron to the helix B ; for when the battery contact was con- 
tinued, the galvanometer still resumed its perfectly indifferent state (28.). The 
spark was rarely seen on breaking contact. A small platina wire could not be 
ignited by this induced current ; but there seems every reason to believe that 
the effect would be obtained by using a stronger original current or a more 
powerful arrangement of helices. 
33. A feeble voltaic current was sent through the helix B and the galvano- 
meter, so as to deflect the needle of the latter 30° or 40°, and then the battery 
of one hundred pairs of plates connected with A ; but after the first effect was 
over, the galvanometer needle resumed exactly the position due to the feeble 
current transmitted by its own wire. This took place in whichever way the 
battery contacts were made, and shows that here again (20.) no permanent in- 
fluence of the currents upon each other, as to their quantity and tension, exists. 
34. Another arrangement was then used connecting the former experiments 
on volta-electric induction with the present. A combination of helices like 
