ON THE ELECTRIC COLUMN. o^ 



en/umn, winch being attributed to a Jhtid known to possess, theflnidin the 



in the propel" sense, the swiftness of lig/ining, must appear ^"'"'"'^> 



a paradox. Rapidity of motion certainly belongs to the 



electric JiuicU when darting in a torrent; but the /fc/r?c from its ten- 



matfer, of which it is composed, has a tendency to adhere f^"^y '" ''''^•■ 



,, , .. .-Ill . • ■ ,• here to bodies. 



to all bodies, air jnclnded ; and it is this very property, as 



expUiined by Sig. Volta, which occasions the electric mo- 



tio7is, when the jlti'id, tending to move by a rnpture of its 



equilibrium^ is more rebictant to be separated from the 



body which possesses it, than the Uuter to follow \.hQ Jluid 



in its motion. 



The etfect of this tendency of the electric fluid towards Analogy in w^v- 

 bodies, in retarding its mo^iow wiiUin the column, is anato- ^^^' 

 gous to an effect observed in water. AVhen water is kept in 

 motion in a channel by a constant snpply, it is seen to take 

 its course in the middle, leaving behind the particles re- 

 tarded by their tendency towards the sides, which is de- 

 creasing as the distance increases. But the analogy is more 

 direct, when water is conlifled in a pond, beset with aqua- 

 tic plants or other impediments; for tlie motions impressed 

 on that water at one side of the pond, thoiigh continued, if 

 small, are but slowly and seldom completely commanicated 

 through the whole space. The case is the same with respect 

 to the electric jiuid set in motion by the property of the co- 

 lumHi not only when contined within it, but when a current 

 is produced; which effect will be shown by some experi- 

 ments, after I shall have explained some parts of the hgure 

 annexed to this paper. See Plate ill. 



The dimensions of this yzi^zfre- are li,alf those of the on- Explanation 

 ginal : it consists of many parts which I shall successively of the plaie^. 

 describe, beginning by those which relate to my present 

 object : its fundamental parts are an electric column, witli its 

 electroscopes. The former is represented at A, B, supported 

 horizontally on two pillars J, I, consisting of solid glass 

 rods, covered with sealing wax, or with some other insulat- 

 ing varnish, and fastened on the wooden base 2, -2, by fe- 

 male screws underneath. The column itself is composed of 

 600 groups, formed of zinc pUues 0*7 inch diameter, and 

 equal pieces of plain Dutch gilt paper ; the copper side of 

 which being turned towards A, this is the positive extremity 



