52 Mr. cavallo’s Account of 
which I fufpend a more or lefs fenfible pith-ball eledtro- 
meter as occafion requires. 
This inftrument is fattened to the fide of the window- 
frame, where it is fupported by ftrong brafs hooks at 
cb. The part H hands out of the window, with the end 
F a little elevated above the horizon. The remaining part 
of the inftrument pafies, through a hole in a glafs of the 
fiath, into the room, and no more of it touches the fide 
of the window than the part bc. 
When it rains, efpecially in flying fhowers, this inftru- 
ment, handing in the fituation above defcribed, is fre- 
quently electrified ; and by the diverging of the electrome- 
ter the quantity and quality of the electricity of the rain 
may be obferved, without any danger of miftake. With 
this inftrument I have obferved that the rain is generally 
electrified negatively, and fometimes lo ftrongly, that I 
have been able to charge a fmall coated phial at the 
wire ag. 
This rain-electrometer fliould be fixed in fuch a man- 
ner that it may be eafily taken from and replaced at the 
window as occafion may require ; for it will be neceflary 
to clean it very often,, particularly when a fhower of rain 
is approaching.. 
2X.PE.RT-- 
