ON THE ELBCTRIC COLUMN. |55 



wire itself 5/ac^ to the edge of the lamina. Following how- 

 over farther the idea of discharging the bead by its wire 

 meeting with the smallest conducting mass possible, I 

 thought of substituting for the brass lamina a single silver 

 icire like that of the bead ; and at last I thus succeeded. 

 This is the part of the ^^Mre which I am going to de- 

 scribe. 



The last alteration I found necessary to make in the ap- Farther addU 

 paratus, which is represented in the Jigure, not being made paratus. **^' 

 at that time, it must be supposed for the present, that the 

 piece 28 is represented by the lead slip 19, 19. The piece 

 23 is a brass spring of about half an inch in breadth at the 

 base 24, where passing under the bent part of an upright 

 brass piece 25, it is thus fixed with the latter, by screws, 

 on the base. The breadth of the spring 23 diminishes to- 

 ward its end, where it is terminated by a brass wire boio 

 22; in this is stretched the thin silver wire 21, against which 

 that of the bead comes to strike. The upright brass piece 

 25 has at the top a screw 26, pressing against the spring, 

 and servmg to produce small motions, backwards or for- 

 wards, of the horizontal wire 21, previously brought nearly 

 to the proper distance, by moving the lead base 19, J 9, 

 The moment of the meeting of the two silver wires is to 

 be an instant before the bead strikes the ball 18 : theq, by 

 a jerk produced at the meeting of the wires, t\\e sticking of 

 the bead to the ball is effectually prevented. 



This was only finished ii) the beginning of last April ; The strikings 

 the strikings of the bead were then regular and uninter- effected by tli« 

 rupted, while there was no shake of the apparatus itself; 

 but being on a table, I soon found, that by walking in 

 the room, and also by the agitation of the air in opening 

 and shutting the door, the motions of the bead( were dis- 

 turbed. This determined me to fix, against the side of the 

 room which had a proper light, a glared box, in which I 

 placed the apparatus ; and | fixed under it, at its level, a 

 little table, in order to place there additional columns, 

 which became necessary to increase the power of the instru-j 

 inent. 



This apparatus being at last ready for regula^r observa- jrournal of the 

 ti^ns, I began the meteorological journal which I had in ^^!^?^^'!^°^ 



view. 



