to Electricity and Magnetism, 263 
a coil No. b helix No. 1, c coil No. 3, and d helix No. 2. 
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 inductive effects at the 
beginning and ending cannot be distinguished from each 
other, and we can only observe a single impulse, which, how- 
ever, may be considered as the difference of two impulses in 
opposite directions. 
91. The first experiment happened to be made with a cur- 
rent 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 needle it was found that this current was in the same 
direction with the secondary and primary currents^. By a 
too hasty generalization, I was led to conclude, from this ex- 
periment, that the currents of all orders are in the same di- 
rection as that of the battery current, and I was the more 
confirmed in this from the results of my first experiments on 
the currents of ordinary electricity. The conclusion, how- 
ever, caused me much useless labour and perplexity, and 
was afterwards proved to be erroneous. 
92. By a careful repetition of the last experiment, in re- 
ference to each current, the important fact was discovered, 
that there exists an alternation in the direction of the currents 
of the several orders commencing with the secondary. This 
result was so extraordinary, that it was thought necessary to 
establish it by a variety of experiments. For this purpose 
the direction was determined by decomposition, and also by 
the galvanometer, but the result was still the same ; and at 
this stage of the inquiry I was compelled to the conclusion 
that the directions of the several currents were as follows : 
Primary current 4- 
Secondary currerit 4- 
* It should be recollected that all the inductions which have been men- 
tioned were produced at the moment of breaking the circuit of the battery 
current. The induction at the formation of the current is too feeble to 
produce the effects described. 
