2^0 



Sometimes the 

 ground con- 

 tains less elec- 

 tricity than the 

 »ir near it. 



Remarks on 

 the column. 



ON THE ELECTRIC COLUMN. 



{as well as when it is connected with the copper side) it 

 must rise more rapidly towards the &a// 18, in proportion 

 as the electric slate of the latter differs more from its own. 

 We know that in the first case (that of my observations), 

 when the ball 18 communicates with the copper extremity 

 of the columns, it is negative, and thus differs from the pen.' 

 dulum as negative from positive ; the standard of which, 

 according to the important determination of Sig. Volta, 

 is the actual electric state of the ambient air. Now, the 

 observations contained in the above table show, that the 

 frequency of the strikings is not always the greatest, when 

 the ball 18 is undoubtedly negative by communicating with 

 the copper side of the columns ; it being often equal, and 

 sometimes even greater, when the ball communicates with 

 the ground. This is a remarkable phenomenon, showing^ 

 that sometimes the ^roMwd contains less electric fluid than 

 the air near it, and it may in future lead to some important 

 discovery concerning the operations going on at the surface 

 of the ground depending on the atmosphere. 



I have employed much time and labour, to arrive at the 

 entrance of this new road in the investigation of terrestrial 

 phenomena : the entrance^ I say, for I do not even consider 

 it as completely open. With respect to the instrument 

 itself, 1 may judge, that it is susceptible of farther im- 

 provements, both in the composition of the column, and in 

 the machinery added to it : for in such a complication of 

 new physical efl^ects and mechanical dispositions of parts, 

 it is not to be expected, that every thing can be conceived by 

 one individual. The very composition of the column might 

 be improved with regard to the intensity of effect, by some 

 other metallic coating than that of copper on paper, which 

 I have employed on account only of its being ready pre- 

 pared by using Dutch gilt paper. In some trials, I have 

 found more effect in using paper covered with real gold, 

 and with silver; and I have also found some advantage in 

 doubling tlie Dutch gilt paper, by pasting a thin papei" 

 over its own pa})er. Many such trials may be made with a 

 proper condenser, before whole colu7nns are composed. As 

 for the arrangement of the machinery connected with the 

 column, the instrument which I have described having been 



successively 



