126 Conti^ibutions to Electricity and Magnetism. 



24. The next step in the investigation was to determine the 

 direction of the currents of the different orders produced by the 

 beginning induction, and for this purpose the magnetizing spirals 

 (5) were used, and the results obtained by these verified by the 

 indication of the galvanometer. It should be stated here, as a fact 

 which was afterward found of some importance, that although the 

 needle of the galvanometer was powerfully deflected when the 

 instrument was placed in the circuit of the secondary current, yet 

 a very feeble effect was produced on it by the action of a current 

 of the third, fourth, or fifth order. The directions, however, of 

 these currents, as indicated by the feeble motion of the needle, 

 were the same as those given by the magnetizing spiral. 



25. The direction of the different currents produced at the 

 making of the battery current, as determined by these instru- 

 ments, is as follows, viz. the direction of the secondary current is, 

 as stated by Dr. Faraday, adverse to that of the primary current, 

 and also, the direction of each succeeding current is opposite to 

 that of the one which produced it. We have, therefore, from 

 these results, and those formerly obtained, (III, 92,) the following 

 series of directions of currents, one produced at the moment of 

 beginning and the other at that of the ending of the battery current. 



Primary current, . , 

 Secondary current, . , 

 Current of the third order. 

 Current of the fourth order, 

 Current of the fifth order, 



26. These two series, at first sight, may appear very different, 

 but, with a little attention, they will be seen to be of the same 

 nature. If we allow that the induction at the ending of a gal- 

 vanic battery should be opposite to that at the beginning of the 

 same, then the sign at the top of the second column may be call- 

 ed minus instead of plus, and we shall have the second series — 

 -\ h alternating precisely like the first. 



27. In connexion with the results given in the last two para- 

 graphs, it is due to Mr. Sturgeon that I should state that, in a let- 

 ter addressed to me, and published in the Annals of Electricity, 

 he has predicted, from his theory, that I would find on exami- 

 nation, the series of alternation of currents for the beginning 

 induction which I have here given. I may however add, that 



