324 CONTRIBUTIONS TO ELECTRICITY AND MAGNETISM. 



each current, the important fact was discovered, that there exists an 

 alternation in the direction of the currents of the several orders^ com- 

 mencing 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, -f- 



Secondary current, -f~ 



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 pri- 

 mary and secondary currents, and it appeared that this exception 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 primary and secondary, and the anomaly would 

 thus disappear. Arrangements were therefore made to fully satisfy 

 myself on this point. For this purpose the decomposition of dilute 

 acid and the use of the galvanometer were resorted to, by placing the 

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

 of the coil, as in the arrangement described by Dr Faraday (ninth se- 

 ries) ; but all the results persisted in giving a direction 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 bat- 

 tery current on itself. 



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

 direction, they offer 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 action of this, as has been 

 shown, is in the same direction as the current from the battery, yet it 



