490 Prof, J. Henry's Contributions 



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 thai of the one which produced it. We 

 have, therefore, from these results, and those formerly ob- 

 tained (III. 92.), the following series of directions of currents, 

 one produced at the moment of beginning, and the other at 

 that of ending of the battery current. 



At the beginning, At the ending. 



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 dif- 

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

 the same nature. If we allow that the induction at the end- 

 ing of a galvanic battery should be opposite to that at the 

 beginning of the same, then the sign at the top of the second 

 column may be called minus instead of plus, and we shall 



have the second series — | 1- alternating precisely like 



the first. 



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

 paragraphs, it is due to Mr. Sturgeon that I should state that, 

 in a letter addressed to me, and published in the Annals of 

 Electricity, he has predicted, from his theory, that I would 

 find, on examination, the series of alternation of currents for 

 the beginning induction which I have here given. I may, 

 however, add, that it appears to me that this result might 

 have been predicted without reference to any theory. There 

 was no reason to suppose the induction at the beginning 

 would be different in its nature from that at the ending, and 

 therefore the series which would be produced from the former 

 might be immediately inferred from that belonging to the 

 latter, by recollecting that the direction of the induction at 

 the beginning should be opposite to that at the ending. I do 

 not wish it to be supposed, however, from this remark, that 

 1 had, myself, drawn any inference from my experiments as 

 to the alternations of currents which might be produced by the 

 benfinning induction ; the truth is, that this action was so fee- 

 ble with the arrangement of apparatus I employed, that I 

 supposed it could not produce a series of currents of the dif- 

 ferent orders. 



28. In the course of the experiments given in this section, 

 I have found that a shock can be produced without using a 

 coil, by arranging about ten elements of the battery in the 



