Observations on some Experiments in Electricity. 65 



Some authors have represented that the outer sheet next to the 

 negative ball, would be found more extensively torn than that to which 

 the positive should be applied. 



This has not been verified by my experiments when the halls viere 

 of equal size. In performing the experiment on sixty sheets of letter 

 paperj it was observed that several of the outer sheets on each side, 

 were torn from the point of contact as a centre, in radiant lines about 

 half an inch in length. But the separate points of paper did not a/Z, 

 on either side of the package, appear to be thrown outwards. On 

 one side of the hole they seemed to have been dashed into the cavity, 

 and on the other, were inclined upwards around the center. As the 

 smallest of the perforations was about one-tenth of an inch in dia- 

 meter, it was easy to distinguish that every sheet partook of the double 

 protrusion described by Synimer. The courses of the opposing cur- 

 rents were not always found to be two parallel straight lines,- but ra- 

 ther indicated a double spiral, like two strands of a cord. 



7. The Card between the tivo Poles. 



In repeating the experiment of Mr. Lullin upon a card covefed 

 with Vermillion, and interposed between the two wires from a battery, 

 so that one of the latter should touch each of its faces, the usual result 

 was obtained, of forming a black streak upon the colored strrface 

 from the positive, to a point opposite to the negative wire, where a 

 hole was perforated, with a burr protruded, on both sides of the pa- 

 per. On varying the experiment according to the method of Tre- 

 mery, by placing the card in vacuo, and using small wires for the two 

 ^oZes, similar perforations, ten or twelve in number and in a line, 

 more than three quarters of an inch in length, vVere produced at a 

 single discharge. This line occupied the whole distance between 

 the positions of the two opposite wires. In other instances, the dis- 

 tance being increased to several inches, the perforations were less 

 numerous, commonly no more than one or. two, and were found at 

 intermediate points between the two poles, but did not as sometimes 

 represented, show any decided relation between the degree of ex- 

 haustion, and the distance from the negative wire. It is evident from 

 these facts, that the point of rupture in vacuo is a matter dependent 

 chiefly on the accidental Weakness of the paper at one point more 

 than at another. For if the card be strong, but not very wide, the 

 electricity will sometimes take a circuit over the edge, instead of fol- 

 lowing the direct path and passing through the paper. This resuU 

 Vol, XXV.=-No. 1. 9 



