

VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 745 



discs are then placed horizontally on a table, one over another continually alter- 

 nating, in a pile as high as it will well support itself without tottering and falling 

 down ; beginning with a plate of either of the metals, as for instance the silver, 

 then upon that one of zinc, over which is to be put the soaked card ; then other 

 3 disks, over these in the same order, viz. a silver, next a zinc, and then 

 another moistened card, &c. 



After having raised the pile to about 20 of these stages or triads of plates, it will 

 be already capable, not only of affecting Cavallo's electrometer, assisted by the con- 

 denser, so as to raise it 10 or 15°, charging it by a simple touching, so as to cause 

 it to give a spark, &c. as also to strike the fingers with which we touch the top or 

 bottom of the column, with several small snaps, the fingers being wetted with water. 

 But if to the 20 sets of triplets of the plates be added 20 or 30 more, disposed in 

 the same order, the actions of the extended pile will be much stronger, and be felt 

 through the arms up to the shoulders; and by continuing the touchings, the 

 pains in the hands become insupportable. 



Mr. V. constructs and combines his apparatus in various ways and forms, more 

 or less powerful, convenient, or amusing. One is as follows, fig. 1, pi. 13, which 

 he calls a couronne de tasses. He disposes in a row a number of cups, of wood, 

 or earth, or glass, or any thing but metal, half filled with pure water, or salt water, 

 or lye ; these are all made to communicate in a kind of chain, by several metallic 

 arcs, of which one arm or link Aa, or only the extremity a, immersed in one of 

 the cups, is of copper, or of copper silvered, and the other z, immersed in the fol- 

 lowing cup, is of tin, or rather of zinc, the 2 being soldered together near the 

 crown of the arch. It is evident that a series of these cups, thus connected to- 

 gether, either in a straight or curved line, by the 2 metals and the intermediate 

 liquid, is similar to the pillar or pile before described, and consequently will exhibit 

 similar effects. Thus, to produce the commotion or sensation in the hands and 

 arms, we need only dip one hand into one of the cups, and a finger of the other 

 hand into another cup, sufficiently distant from the former ; then the action will 

 be so much the stronger as the 2 cups are farther asunder, or have the more in- 

 termediate cups ; and consequently the greatest by touching the first and the last 

 in the chain. 



As to the structure in the other method, by the column or pile, Mr. V. found out 

 various ways to prolong and extend it, in multiplying the metal plates without shaking 

 it down ; to render this instrument convenient, portable, and durable ; and, among 

 others, the 3 methods exhibited on figs. 2, 3, 4, pi. 13. In fig. 2, m m m m, are 

 upright bars or rods, to the number of 3, or 4, or more, erected from the bot- 

 tom of the pile, and extended to a convenient height, inclosing the pile like a cage 

 to prevent its falling. These rods may be either of glass, wood, or metal ; only, 

 in this last case, they must be hindered from touching the metal plates ; which 

 may be done, either by covering each metal rod with a glass tube, or by interpo- 

 sing between them and the pile some bands of cerecloth, or oiled paper, or sim- 



VOL. XVIII. 5 C 



