EFFECTS or LIGHTNING, 121 
ceived no other injury than a flight difcoloration in one 
of her feet, with a fenfe of numbnefs in both, which dif- 
appeared the following day. 
From this ftack of chimneys, in the direction of the 
ftorm, that is Southweft, there is no lightning rod, nor 
any more elevated building, for a confiderable diftance, 
which might have intercepted the ftroke; but immediately 
to the North and North Eaft, the adjoining buildings are 
much higher, and there is one pointed rod, at no great 
diftance. 
_ It is remarkable that the lightning paffed through the 
two chimneys only which had fire in them, though two 
others were contiguous. And we were told that the chim- 
ney which it quitted at the roof had very little fire in it. 
The late Mr. Henry, in a paper read before the Philofo- 
phical Society, has endeavoured to fhew that heat 1s the 
condudting medium of the electrical fluid. It may perhaps 
be doubted whether it is the matter of heat, or the effects 
of it in rarefying bodies that difpofes them to conduct 
electricity. It is however certain that barely rarefying the 
the air, without any additional heat will make it conduct 
the ele€trical matter readily, and probably it was the co- 
lumn of rarefied air which conducted the lightning down 
thefe chimneys. Whilft volcanos are throwing forth pro- 
digious columns of fire {moke and afhes, corrufcations of 
lightning are frequently feen amongft them: the exten- 
five rarefaction of air, produced by thefe immenfe fires, 
affording the means of reftoring the equilibrium of the 
electrical fluid to very great diftances. We may from 
hence conclude that it is fafer to be neara chimney that 
has no fire in it, during a thunder-guft, than one that 
has fire. 
The houfes above defcribed were ftruck in the begin- 
ning of the thunder-guft, and before it had rained any. 
Sometime afterwards, in the greateft fall of rain, the light- 
VOL. II. 7 Q. ning 
