230 Contributions to Electricity and Magnetism. 



ists an alternation in the direction of the currents of the several 

 orders, commencing with the secondary. This result was so ex- 

 traordinary, that it was thought necessary to estabhsh it by a va- 

 riety of experiments. For this purpose, the direction was deter- 

 mined 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 adopt the conclusion that the directions of the sev- 

 eral currents were as follows : 



Primary current, ..... -f 

 Secondary current, .....-{- 

 Current of the third order, . . . — 



Current of the fourth order, . . . -}- 



Current of the fifth order, . . . — 



93. In the first glance at the above table, we are struck with 

 the fact that the law of alternation is complete, except between 

 the primary and secondary currents, and it appeared that this ex- 

 ception might possibly be connected with the induced current 

 which takes place in the first coil itself, and which gives rise to 

 the phenomena of the spiral conductor. If this should be found 

 to be minus, we might consider it as existing between the pri- 

 mary and secondary, and the anomaly would thus disappear. Ar- 

 rangements were therefore made to satisfy myself fully on this 

 point. For this purpose, the decomposition of dilute acid and the 

 use of the galvanometer were resorted to, by placing the appara- 

 tus between the ends of a cross wire attached to the extremities 

 of the coil, as in the arrangement described by Dr. Faraday; 

 (ninth series ;) but all the results persisted in giving a direc- 

 tion to this current the same as stated by Dr. Faraday, namely, 

 that of the primary current. I was therefore obliged to abandon 

 the supposition, that the anomaly in the change of the current is 

 connected with the induction of the battery current on itself 



94. Whatever may be the nature or causes of these changes in 

 the direction, they off'er a ready explanation of the neutralizing 

 action of the plate interposed between two conductors, since a 

 secondary current is induced in the plate ; and although the di- 

 rection of this, as has been shown, is the same as that of the cur- 

 rent from the battery, yet it tends to induce a current in the adja- 

 cent conducting matter of a contrary direction.* The same ex- 



* See paragraph 130, Fig. 15. 



