504 Prof. Marianini on the Currents produced by the 



charged the Ley den jar upon the other similarly covered, the 

 needle deviated, as when there was no naked band between 

 the actuating and the actuated plates. 



But if the two ends of the metallic band between the ac- 

 tuating and the actuated plates were connected, then the 

 Leyden jar being discharged as above, thei'e was no deviation 

 in the re-electrometer, or it was very small, and only took 

 place when the jar was considerably charged; which appears 

 to me to prove, that when the actuating current operates upon 

 a closed metallic circuit, it induces in it a contrary current, 

 which either wholly or in part destroys the effect of the ac- 

 tuating current upon the second actuated band. 



I connected the ends of the middle band with the re-elec- 

 trometer, and now connected the ends of the third band with 

 them, now employed them unconnected. In the first case, the 

 jar being discharged upon the first band, the deviations were 

 somewhat small, and in the second evidently greater. There 

 was not so much difference in the two cases as in the prece- 

 ding experiment, in spite of the small interval between the ac- 

 tuating band and the immediately actuated one. 



XV. Two silvered copper wires were placed parallel to 

 each other, each by means of two pegs of wood covered with 

 sealing-wax, at one meter distant from each other, and move- 

 able, so as to allow the distance between the wires to be 

 varied, while they still remained parallel. Having connected 

 one of these with the ends of the wire of a re-electrometer, 

 and discharged the Leyden jar upon the other, I saw that 

 the induction visibly took place, even when the distance be- 

 tween the actuating and actuated wires was seven centime- 

 ters. 



I have already observed in § XL, that when the actuation 

 only took place on a small space of the actuated conductor, 

 the effect was less. Now, applying the ends of the re- electro- 

 metric wire to two points more or less distant from each other, 

 I have observed that the signs of an induced current began 

 to appear when the extent of wire subject to actuation was 

 about a centimeter and a half, and the distance from the ac- 

 tuating wire two millimeters. When the actuated wire was 

 three centimeters long a degree of deviation was obtained, 

 and this increased to ten degrees when the extent of actuated 

 wire was six or seven decimeters. It did not increase on the 

 wire being considerably lengthened, which I tried to the ex- 

 tent of a meter. I have observed the same on varying the 

 length of the actuating wire. 



XVI. I connected the ends of a perfect Nobili's multiplier 

 with those of the actuated metallic wire, and discharged the 



