[ 357 ] 
is frequently obferved to be the cafe, immediately af- 
ter a flafh of lightning. Yet when the air is very 
dry, the apparatus will continue to be electrified for 
ten minutes, or a quarter of an hour, after the clouds 
have paffed the zenith ; and fometimes till they ap- 
pear more than half-way towards the horizon. Rain, 
efpecially when the drops are large, generally brings 
down the eleCtrical fire : and hail, in fummer, I be- 
lieve never fails. When the apparatus was lafh elec- 
trified, it was by the fall of thawing inow * which hap- 
pened fo lately, as on the 12* of November; that 
being the twenty-fixth day, and fixty-fird time, it 
has been electrified, fince it was firft fet up ; which 
was about the middle of May. And as Fahrenheit’s 
thermometer was but feven degrees above freezing, 
it is fuppofed the winter will not intirely put a flop 
to obfervations of this fort. At London, no more 
than two thunder-dorms have happened during the 
whole fummer : and the apparatus was fometimes fo 
ftrongly electrified in one of them, that the bells, 
which have been frequently rung by the clouds, fo 
loud as to be heard in every room of the houfe (the 
doors being open), were filenced by the almod con- 
ftant dream of denfe eleCtrical fire, between each 
bell and the brafs ball, which would not differ it to 
drike. 
I diall conclude this paper, already too long, with 
the following queries: 
1. May not air, fuddenly rarefied, give eleCtrical 
fire to, and air fuddenly condenfed, receive eleCtrical 
fire from, clouds and vapours pafling through it ? 
2. Is not the aurora borealis , the flafhing of eleCtri- 
cal fire from pofitive, towards negative clouds at a 
great 
