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the pafTage through the air was fHll half an inch i 
and taking three yards and a half of wire that was 
one fifth of an inch thick, the fpark in the air was 
half an inch, and fometimes near three quarters of 
an inch. Making ufe of only half the length of this 
wire, the pafTage through the air was only half that 
diflance, or l.th of an inch. When 1 kept the place 
of near contadl about the middle of this wire, and 
made the explofion at the extremities of the whole 
wire, I was obliged to bring them about as near again, 
/. e. to little more than one eighth of an inch, before 
the pafTage would be through the air j To that the 
force of the whole explofion mufl: have been greatly 
weakened by its pafTing through fo much of the Wire. 
Laftly, I took a pair of kitchen tongs, the legs of 
which were two feet, and the fmalleft part of them 
above half an inch in diameter; when the circuit was 
made ^bout one fixth of an inch in the air (for at 
that diffance from one another the ends of the tongs 
had been fixed) rather than through four feet of that 
thick iron. ' 
Notwithflanding this evident pafTige of the eledlric 
matter through the air, at the fame time that a me- 
tallic circuit was provided for it ; it was certain that 
the whole of the charge did not pafs in the air : for 
when I extended ^-d of an inch of fmall iron wire 
between a and it was only made red-hot by the 
difchargc ; whereas above two inches of it would 
have been exploded, if there had been no other me- 
tallic circuit at all. 
As the elecflric fire meets with fo much obfirudion 
in pafiing through a circuit of iron of this thicknefs, I 
make no doubt but that it is confiderably obfi:ru(5led 
in 
