[ I 9 ° ] 
ftngle fparks, the jars are then removed, and the 
conductor isfupported by two glafs piiiars, fuch as are 
ufed in the difcharging apparatus; one end of which 
fits into holes made in the board at M and N, and the 
other end having a wire fixt to it, iupports the 
conductor. 
OPQR, the difcharging frame placed on a table, 
and confiding of the following pieces. 
QSR,a mahogany board twenty inches long and 
feven broad : about the middle of this board a narrow 
brafs plate is let into the thicknefs of the wood, reach- 
ing from S to a. At the extremity which projects out 
of the board, there is a loop into which the end of the 
bent wire Z is fitted by being ground into it, the other 
extremity receives the end of the nut S. 
S, a brafs nut made with a double ferew, the lower 
end being a male' ferew, to fafien it to the brafs plate; 
and the upper end a female ferew, to receive the ends 
oi different wires and other pieces which fit into it for 
performing various experiments. 
OQ, PR, two glafs pillars about twelve inches long 
and an inch thick, made with fhoulders at the end, 
which fit into the board QR, and the rail OP. 
OP, a mahogany rail three inches broad and iL 
thick, nearly the fame length with the board QR, 
which receives the upper ends of the glafs pillars. 
TV, a thick brafs wire, which paffes through the 
middle of the rail, and, by means of a ferew at d , may 
be ffiopt at any height. At the upper end V. of this 
wire is a loop, and at the lower end T a ferew, to 
which pieces are fixt to anfwer thofe in the nut S. 
W, a folid piece of brafs, through which the 
upright wire TV paffes, which may be fhifted to any 
part 
