g^ ON THE ELECTRIC COLUMN. 



gree of divergence of the gold leaves at both extremities, 

 J)ti/ paper not being so good a conductor as wet cloth, the 

 electric tirects were not so great as they would have been 

 with the latter; but they were sufficient for my purpose. 

 I kept this apparatus for some days, observing the diver- 

 gences in different parts of the day, and the greatest, 

 which happened to be at the zinc side, was of 0*3 of an 

 ineh. 

 E»p S. Exp. 5. I then placed the brass tripods between each 



zinc (date and the copjur side of th« papers, the paper side 

 ' of which se[)arated the binary grouj.s of metals., as did the 

 wet cloth ill the former experiment: the electric effects re- 

 mained the same as they wyre in Exp. 1, without the tri' 

 pods. 



It came then into ray mind, that the tripods, being of 

 brass, might alone profbice some etfect, with only plain 

 paper to separate these groups of zinc and brass; but the 

 latter having but a small mass, the transmission of electric 

 Jluid lilon^ tha column could not but be slower; and this 

 was the very reason which determined me to the trial, as an 

 experiment that would also relate to the cause which renders 

 Effect of the the column an aerial electroscope: this cause is the action of 

 '^"' the ambient air, the iuj mediate effects of which are, to 



lessen the positive state of one of the extremities, and the 

 negative state of the other, according to its own electric 

 state J and more slotvness in the motion of the fluid giving 

 more time to this actioi; of the ambient air for diminishing 

 the e/ec/ric indications at the extremities of the columnt these 

 symptoms were to be smaller. This therefore induced me 

 to make the following experiment. 

 Exp. 5» Exp. 3. I mounted the column with 80 groups com* 



posed of zinc plates with only the brass tripods, separating 

 them with pieces of tcriting paper, and I kept also this co- 

 lumn for some days, observing the electroscopes at its extre- 

 mities: they had the same variations which I had before 

 observed, but very small, and the greatest divergence, which, 

 as it is commonly, was in the middle of the day, did not 

 exceed O'l of an inch. 

 Slowness of I now come to that slowness mentioned above in the mO' 



the motion of Hou o( \.he electric Jlvid produced by the property of the 



^ column, 



