502 Prof. Marianini on the Currents produced by the 



it, never produced any difference in the results ; certainly the 

 effects were less when the distance between the two points of 

 the plate upon which the jar was discharged was less : and if 

 such distance was sufficiently small, as for example, one cen- 

 timeter, there was no indication of an induced current, al- 

 though the actuating plate might only be separated from the 

 actuated by a very fine little portion of silk or wool. 



XII. A band of lead, one meter long and two centimeters 

 broad, was for the space of six decimeters inclosed in silk rib- 

 bin, leaving two decimeters of it bare at each extremity. I 

 applied over this, but only for the space of five centimeters in 

 the middle, a longer band of the same metal, and in order that 

 they might be in better apposition to each other, I surrounded 

 them both with silk thread in an open coil for all the said 

 space. The uncovered band was then folded back, half a de- 

 cimeter of the covered band remaining on each side to pre- 

 vent the danger of any metallic contact between the two 

 bands. I connected the extremities of the uncovered band 

 with the metallic wire of a re-electrometer, and then dis- 

 charged the Leyden jars, putting the two coatings in contact 

 with the uncovered extremities of the band covered with silk 

 ribbin, as above mentioned. During these experiments the 

 currents produced by the Leyden-electrical induction caused 

 much greater deviations in the magnetized needle than those 

 which occurred in the experiments hitherto described, in which 

 I caused the actuating current to act upon a part of the ac- 

 tuated band which was not longer than two decimeters. 



The uncovered extremities of the leaden band partially co- 

 vered with silk, having been connected with the wire of the 

 re-electrometer, and the Leyden jar being discharged upon the 

 extremities of the other band, the effects, in similar circum- 

 stances, were perfectly equal. 



Again, with the weakest discharges and even with the first 

 two or three residual charges, manifest indications of induc- 

 tion followed on experimenting with similar bands of lead, 

 placed adjacent, in the manner I have mentioned. 



XIII. Seeing that I could obtain induced currents by means 

 of the weakest actuating currents, also by means of currents 

 which when made to act directly upon the re-electrometer 

 produced deviations less than those which followed from the 

 actuated currents produced by strong discharges of Leyden 

 jars, I thought it would not be time lost to attempt to obtain 

 the inductions of the said induced currents. 



A band covered with silk for the space of seven decimeters, 

 with the extremities bare, had attached to all that part of it co- 

 vered with silk, with the exception of two centimeters on each 



