[ i8 9 ] 
This board has three large holes cut through it, to 
fit the three jars: over thefe holes, on the under lide 
of the board, are nailed three tin plates, which com- 
municate to one another by a flip of tin, and upon 
which the bottom of the jars reft. Under the middle 
•/ 
of this board is alfo fixed by a wooden fcrew a cylin- 
drical piece of wood c, which moves up and down in 
the hollow of the clawed pillar D, and may be ftopt at 
any height by means of the fcrew E ; lo that the whole 
apparatus can be raifed to a height fuitable to any 
electrical machine to which it is applied. 
F, G, H, three glafs jars, about ten inches diameter, 
and fourteen inches high, lined infide and out with 
tin foyl to about two thirds of their height. A piece 
of wood is cemented at their top, through which there 
paffes a thick brafs wire, one end of which fits into a 
focket foldered to the conductor, and to the other end 
within the jar are fixed fmall wires, which fpread and 
form a communication between the infide lining of the 
jars and the conductor. 
KL, the conductor, a tin tube about five feet long 
and three inches in diameter, clofed and rounded off 
at each end. At the end next the machine is fix t a 
piece of brafs made of pointed wires in the fhape of a 
comb, which collects the electrical fire from the 
machine; at the other end is fixt a flight piece of 
mahogany, at the end of which two fmall cork balls 
are fufpended by fine threads, which balls by receding 
from each other, fhew to what degree the power ts 
railed; and when the jars are fully condenied will 
(land nearly upright as in the figure. 
When experiments require to draw a fpark from 
the conductor without a ihock, which we may call 
fingle 
