[;4S3 3 
L. A fteel fcrew, patting through the top of the 
brafs work, whole" threads are diftant nearly 
of an inch from each other. 
M. A well polifhed fpherical piece of brafs, fixed to 
the fcrew L, and oppofite to K. The polilh 
of K and M will often be deft royed by large 
eledrical explolions, and it Ihould again be 
reftored, particularly where the experiments 
require accuracy. 
N. A fcale, with divifions equal to each turn of the 
fcrew. . . . 
O. A circular plate fixed to, and moving with the 
fcrew, pointing at each turn to the divifion 
upon the fcale. This plate is alfo divided into 
twelve, to denote the parts of each turn. 
The principle on which the Eledrometer ads is 
very fimple, being merely this ; the coated phial is 
hereby rendered incapable of accumulating and re- 
taining any more than a certain quantity of the 
eledric. fluid, for any intended experiment, when 
a metallic or non-eledric communication is made 
from the fcrew H to the wire loop E of the ma- 
chine, and that quantity will be proportionate to the 
difiance of K and M from each other, and confe- 
qucntly the explofion and firoke will thereby be re- 
* Thus if a perfon holds a wire faftened to the 
fcrew H in one hand, and another wire fixed to the 
loop E in the other, he will perceive no firoke, n 
K and M are in contad, notwithstanding the cylim*' 
drical glafs-A ads ftronglv. But if, by. turnings 
fcrew L, the ball M is diftant from K P aK ot 
* an 
3 
