AERIAL COLUMN AND AKlllAL ELECTROSCOPIg. g3 



4. I come now. Sir, to my experiments contained in your Mr. De Luc's 

 Journal for October, 1810, whh a Jjgure, half the size of the ^PP^'"^^"*' 

 original, of the apparatus to which I shall refer them, but only 



in their parts concerning Dr Maycock's system. For these ex- 

 periments, beside the eiectroHOpe's at the ends of the column, 

 there is one in the middle. 1 shall call A, that connected with 

 ihe positive end ; B, that at the negative ; and C, an electroscope 

 placed at the middle point : but by taking off the wire 4, it may 

 be made to communicate with any part of the column, the 

 electric state of which is wanted to be known ; and this by 

 means of an insulated wire, so soft as to be easily bent, and 

 thus made to connect, by one end, with the electroscope C, and 

 by the other, with the part of the column the electrical stale of 

 which is wanted to be known. 



5. These experiments, which begin at p. 88 cf the same 

 number of your Journal, referring to some tables given in the 

 conclusion of my preceding paper*, I think better, for an im- 

 mediate reference, to copy them here, with this previous expla- 

 nation, that in all of them, A indicates the positive end, and B, 

 the negative. 



Table I. Table IL Table III. 



Insulated Column. Bin communication A in communication Different 



with the ground. with the ground, states of the 



pile. 



A A A 



+ 10 + i^O 



+ 8 +18 ^ t 



+ 6 +16 — 4 



+ 4 +14 —6 



+ 2 4- 12 — 8 



-h 10 — 10 



— 2 -f 8 — l;^ 



— 4 +6 — 14 

 —-6 +4 — 16 



— 8 +2 — 18 



— 10 — 20 



B B B 



0. 1 come now to the experiments. Experiment 7 is thus Experiments 

 related in p. 88 of your Journal above ouoted. " At the time siiowit ;r the 

 <c 1 / ' r I ; , • I ^ /. . - V , motion of tfie 



when (on account of the electrical state of the air) there are electric fluid 



" simple and equal divergences in the electroscopes at the extre- *•* the column. 

 * Vol. xxvi,p. liery. 



G 2 'f rnities 



