relating to Atmofpheric Electricity . ifcy 
apparatus is calculated to fhew the various degrees of atmo- 
fpherical eleCtricity, and at the fame time to avoid the perni- 
cious efFe&s which may be occafioned by thunder-ftorms, or 
in fhort by any great quantity of eleCtricity in the atmofphere. 
The whole perpendicular height of both parts taken toge- 
ther, from the moift earth to the uppermoft point at the top of 
the rod, is 52 feet. 
Finding, however, that, natwith (landing all the precaution 1 
had taken to procure a good infulatioii, the moift vapour 
of the atmofphere, fixing upon the inflating parts of the appa- 
ratus, rendered it imperf eCt in moift weather; I have lately 
(15th of Sept. 1790) altered the fituarion of the fame rod, fo 
that all the infulating parts are now within the roof of the 
houfe. This I have effected by a hole through the roof of my 
houfe ; by which means I now obtain a confiderably more 
conftant electricity ; which, however, muft not be folely attri- 
buted to the fuperiority of my prefent mode of infulating, but 
to the rod’s being alfo elevated to the additional height of nine 
feet; fo that I confider its pointed part to be at prefent 61 feet 
above the moift earth. 
This improvement of the apparatus, having been made after 
the conclufion of this journal, will be particularly defctibed 
in the next, which I am now carefully continuing. 
It will be neceffary juft to mention the method I have purfued 
in forming the journal of atmofpheric eleCtricity. This has been 
principally by means of the figns exhibited by the pith balls K, 
connected with the rod. "When I find thefe clofed, and not 
attracted by my finger, I then write no figns of eleCtricity. 
When attracted on the approach of my finger, yet not fuffi- 
ciently charged to repel each other, I write weak figns of the 
fluid/ When I find the balls open, and, on the approach of 
excited glafs, the balls clofe, I write they are eleCtrified pofi- 
Cca tively ; 
