2/8 Mr, Mokgan’s Experiments, See. 
and was for feme time difpofed to believe the contrary of what 
I am now convinced to be the truth. Indeed, if we reafon 
a priori , I think we cannot luppofe a perfeCt vacuum to be a 
perfiltt conductor without fuppofing an abfurdity: for if this 
were the cale, either our atmofphere mud: have long ago been 
deprived of all Its eleCtric fluid by being every where fur- 
rounded by a bouhdlefs conductor, or this fluid mu ft pervade 
every part of infinite fpace, and confequently there can be no 
fuch thing as a perfect vacuum in the univerfe. If, on the 
contrary, the truth of the preceding experiments be admitted, 
it will follow, that the conducting power of our atmofphere in- 
creates only to a certain height, beyond which this power be- 
gins to diminifh, till at laft it entirely vaniffies ; but in what 
part of the upper regions of the air thefe limits are placed, I 
will not prefume to determine. It would not, perhaps, have 
been difficult to have applied the refults of fome of thefe ex- 
periments to the explanation of meteors, which are probably- 
owing to an accumulation of electricity. It is not, however, 
rhy prefent defign to give loofe to my imagination. I am fen- 
fible, that by indulging it too freely, much harm is done to 
real knowledge ; and therefore, that one faCt in philofophy well 
afeertained is more to be valued than whole volumes of fpecu- 
lative hypothefes. 
Chatham-Place, Feb. 12, 1785, 
