On # lectro-Dynamic Induction. 229 
arrangement exhibited in Fig. 10. In this case the quantity of 
electricity in the current from the helix appears to be too small 
to produce any effect, unless its power is multiplied by passing it 
reat a conductor of many spires. 
Fig. 10. 
‘ a 
a coil No. 2, b helix No. 1, ¢ coil No. 3, and d or 2a! 
90. The next inquiry was in reference to the direction of these 
currents, and this appeared important in connection with the na- 
ture of the action. 'The experiments of Dr. Faraday would ren- 
der it probable, that at the beginning and ending of the secondary 
current, its induction on an adjacent wire is in contrary directions, 
as is shown to be the case in the primary current. But the whole 
action of a secondary current is so instantaneous, that the induc- 
tive effects at the beginning and ending cannot be distinguished 
from each other, and’we can only observe a single impulse, which, 
however, may be considered as the difference of two impulses in 
opposite directions. 
91. The first experiment happened to be made with a current 
of the fourth order. The magnetizing spiral (11) was attached 
to the ends of coil No. 4, Fig. 9, and by the polarity of the nee- 
dle it was found that this current was in the same direction with 
the secondary and primary currents.* By a too hasty generaliza- 
tion, I was led to conclude, from this experiment, that the currents 
of all orders are in the same direction as that of the battery cur- 
Tent, and I was the more confirmed in this from the results of my 
first experiments on the currents of ordinary electricity. This 
Conclusion, however, caused me much useless labor and perplex-_ 
ity, and was afterwards proved to be erroneous. 
92. By a careful repetition of the last experiment, in reference 
to each current, the important fact was discovered, that there er- 
one 
* It should be en that all the inductions which have been mentioned, 
Were produced at the moment of breaking the circuit of the battery current. The 
induction at the re of the current is too feeble to produce the effects de- 
Scribed. 
