9S 



ON THE ELECTRIC COLUMN. 



of wliatever size. But as, in t.il<ini^ the water at the same 

 level, a pump of .30 feet will bring it three times as high as 

 threcpmrips of 10 feet ; so In the above experiment, the column 

 of 600 groups produced probably three times as much 

 change of density in the electric fluid, with a proporlional 

 divergence, as did the three columns of 200 groups, indi- 

 vidually acting on the same low level, or degree of density, 

 that of the standard of plus or minus. 

 .m.] their size ^^^t if in this case the size of the plates, or the multipli- 

 u> that of the cation of their number at the same numerical distances from 

 of pumps. ^^^ extremities, be indifferent, it is not the same in some 

 other cases, as I shall illustrate by the same analogy. In 

 the above case, the height to which the water was to be 

 raised being the only object, the number or size of the 

 pumps was indifferent ; but if a current is to be produced at 

 that level, either with a certain degree of rapidity, or of a 

 certain volume, then the diameter of the pumps comes in as 

 a condition. The following experiment will show the ana- 

 logy of tliis case, with the effects of the different sizes of 

 plates in the column. 

 Exp. 15, Exp. 15. I made two other columns of 200 groups each; 



but these 1 only cut square, for one of \, and for the other 

 of -J- of an inch, still zinc and Dutch gilt paper. These two 

 cvlumns produced sensibly the same divergence as the for- 

 mer, in the same electroscope ; but in this was already 

 shown the difference in other respects; the time i'ov pro- 

 ducing this divergence was in the inverse ratio of the sizea^ 

 the plates. 



This experiment gives a clear idea of the effect produced 

 by a greater size of the plates, both in the pile ^nd in the 

 column. In the circuit of the former, with the same num- 

 ber of groups, the effects are proportional to the size of the 

 plates, because the current of the electric fluid becoming 

 denser and more rapid in passing through the ivires used in 

 these operations, the effects are greater, in proportion to 

 the number of equal parts of puri'ace, either in a few or 

 many plates, concurring to produce the motion of tiie elec- 

 tric fluid which arrives at the entrance of tliis narrow chan- 

 nel. That difference in the rapidity and density of the 

 j:urrent cannot be discovered in the circuit of the column, 



be-cause 



