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XXIV. Account of a new Electrometer. By Air. Abraham 
Brook ; communicated by Sir Jofeph Banks, Bart. P. R. S. 
Read M ay 30, 1782. 
AAAAN, fig. r. reprefents the electrometer in full fize and 
proportion, {landing on a table, or the like. The foot B is a 
fquare piece of board, 9 1 inches each way, retting on three 
pins C, C, c, feen at the under fide of the foot. C, C, with the 
broad heads, are fcrews to fet the inttrument upright withal. 
D is a folid piece of glafs, which iupports and infulates the 
inttrument from the place on which it ttands. The arms Gi 
and g , with the ball F, turn round on the wire FI (which is 
folid brafs, as may be alfo the arm g), and, when in ule, are 
put near at a right angle with G2 and H, being turned to the 
off fide fo as to be as much as poffible out of each other’s atmo- 
fpheres or the atmofphere of a jar, battery, prime conductor, 
&c. The arms Gi and G2 are hollow tubes of copper, not fo 
heavy as wires. The balls Ii, I2, are made of copper, and 
hollow, fo as to be as light as poflible. K reprefents a kind of 
face or dial plate to the inttrument with its index, which is car- 
ried once round by the motion of the arm Gz with its ball I2 
moving through a quarter, or 90 degrees, of a circle ; this 
motion is given to it by the repulttve power of the charge, &c. 
of electricity between the two balls I2 and L. The ends of 
the index from its center are of different lengths. The longeft 
end reaches to a graduated circle, divided into 90 equal parts, 
anfwering 
