270 Vefcription of an imprcved EleSIromefer^. 



ftrument is intended to be ufed as a difcharglng ele6lronTe- 

 ter, and muft be examined as fueh, no comparifon can pro- 

 perly be made between it and any of the other elc£lrometers 

 hitherto employed. 



Plate VI contains a reprefentation of the electrometer, 

 and the different parts of which it confifts. OP is a board 

 of dry mahogany, twelve inches in length and four in 

 breadth, which ferves as a ftand for the inftrument. In this 

 board are faftened two maiTy glafs pillars, M and N, which 

 fupport the two brafs capes or rings GG, with the two forks 

 of tempered fleel KK fcrewed into them. The two rings 

 GG are well covered with varniflj. 



In the rin"- G is faftened a brafs rod, which terminates in 

 a ball E of the fame metal, and an inch in diameter. The 

 leno;th of the rod and ball together is four inches and a. 

 half. 



A very delicate beam, AB, the arms of which are of un- 

 equal length, moves on a (harp triangular axis (a knife edge) 

 of well tempered fteel on the fork K of the pillar M. It is 

 fevcnteen inches in length, aiid fo conflrufted that the fhort 

 arm forms a third and the long one two-thirds of the whole 

 beam. The fliort arm of brafs furnlfhed with the ball B, 

 exaftly of the fame fize as the ball E, is divided into forty- 

 five parts equivalent to grains. The long arm A is of glafs 

 covered with copal varnifti, and ends in an ivory ball A, into 

 which is fitted an ivory hook R, deftined to fupport the ivory , 

 feale H. In order to render the infulation more complete, 

 lliis fcale ^s fufpended by three hairs. 



A ver)' delicate beam, CD, eleven inches in length, moves 

 on an axis, like the former, on the pillar N, though not heitf 

 fhewn. This bearti is projwrtioned in the fame manner^ 

 one arm being a third and the- other two-thirds of the 

 whole length. The long arm of brafs is furnifhcd at the 

 end with a ball D, and divided into tliirty parts correfpond- 

 ing to grains. The fhort arm of glafs terminates in a lotig 

 roundifh plate C, covered with copal varhlfli. The fteet 



forks 



