in contadl with the chain hanging from the back 
of the cufhion, as is reprefented in the figure. 
With this machine I have frequently drawn elec- 
trical fparks, at the diftance of 12, 13, or 134. 
inches from the prime conductor. Thefe were 
indeed the diftances, to which the electrical fire 
would commonly ftrike. It would fometimes reach 
the diftance of 14 inches; but this was but fel- 
dom. 
Fig. II. reprefents the fame machine, with a 
fmall brafs conductor, inftead of the large one, for 
charging the batteries, which batteries are com- 
pofed of four boxes, each containing 16 jars of 12 
inches high and 4 inches diameter, coated 8 inches 
high ; fo that, in the 64 jars, there are very nearly 
50 fquare feet of coated lurface. The electrome- 
ter * is raifed, fo as to be 4 feet from the bottom, 
which refts on the jars, to the ball at top. I at 
firft fet it on the battery, fo that the ball, at the 
end of the Index, was about one inch higher than 
the balls or wires of the battery, which is the ge- 
neral method of ufing it; but I found, on placing 
it fo low on thefe batteries, that the index would 
move but a very little way, hardly to 15 0 , when the 
battery was full charged; at laft, after trying a 
great variety of experiments, I found, that, placing 
it at the height of 4 feet, the index would rife tc# 
60, with the fame quantity of charge as, in the 
other cafe, raifed it only to 15 : difcharging this 
battery, through a piece of iron wire (not fteel) of 
T |_ of an inch diameter, and three feet nine inches 
long, it flew about the room in innumerable red 
hot balls; on examining thefe balls, they were in 
* Vide Phi 1 . Tranf. Vol. LXLI. p. 359. 
2 general 
