s 
[ *39 ] 
making my experiments on that fide of the houfe 
where the wind had leafl power. 
I have found the air, in winter, at a proper didance 
from buildings, trees, mails of fhips, &c. very fen- 
libly eledrified, during a frofly or foggy flate of the 
weather ; and in mills too, but in a lefs degree : I 
have alfo difcovered fmall figns of it in .calm and 
cloudy weather. 
The air, in fummer, never fhewed any fign of 
eledricity, except when a fog happened in the cool 
of the evening, or at night ; in which cafe, I always 
difcovered manifefl marks of eledricity, fenfibly 
weaker than thofe obferved in winter fogs, but pre- 
cifely of the fame kind, that is, pofitive. 
I have often examined the flate of the air, at the 
time of an Aurora borealis, and could not difcover 
any indication of eledricity, except when a fog had 
appeared at the fame time ; in which cafe, the elec- 
tricity has been, in every refped, the fame as that of 
a fog at any other time. Once, indeed, during an 
Aurora borealis on a remarkable ferene night, 1 dif- 
covered fome figns of a very weak pofitive eledri- 
city. 
As the eledricity of the air is generally pofitive (I 
never knew an exception but one, which prefented 
itfelf during a fog on a winter day, that proved un- 
commonly warm), is it not reafonabie to believe, that 
cold eledrifies the atmofphere pojitively ? and, if fo, 
may not one be led to imagine, that heat eledrifies 
it negatively ? But this I only offer as a conjedure, 
not being able to advance any thing decifive on the 
fubjed, and knowing that one fort of eledricity may 
T 2' often 
