10 CONTRIBUTIONS TO ELECTRICITY AND MAGNETISM. 



the induction at the ending 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 f- 



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 pub- 

 lished 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 begin- 

 ning 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 the- 

 ory. 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 I had, myself, drawn any infe- 

 rence from my experiments as to the alternations of currents which might be 

 produced by the beginning induction; the truth is, that this action was so feeble 

 with the arrangement of apparatus I employed, that I supposed it could not 

 produce a series of currents of the different 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 form of a circle, and placing the helix within this. The 

 shock was felt in the hands at the moment of closing the circuit, but the effect 

 at opening the same was scarcely perceptible through the tongue. An attempt 

 was also made to get indications of induction by placing the helix within a cir- 

 cle of dilute acid, connected with a battery instead of a coil, but the effect, if 

 any, was very feeble. 



29. I have shown, in the second number of my contributions, that if the 

 body be introduced into a circuit with a battery of one hundred and twenty 

 elements, without a coil, a thrilling sensation will be felt during the continu- 



