;0 Mr. cavallo’s Account of 
VI. An Account of fome new MeBriccil Experiments. By 
Mr. Tiberius Cavallo: communicated by Mr. Henley, 
F. R. S. 
'DESCRIPTION AND USE OF THE ATMOSPHERI- 
CAL ELECTROMETER. 
Head Dec. 19:, T 7 ' I G. I. represents a' very fimple inftru- 
1776. S’ 
A ment, which I have contrived for 
^making obfervations on the electricity of the atmofphere, 
and which on feveral accounts feems to be the molt ufeful 
inftrunient hitherto invented for that purpoie. a b is a 
common jointed fillring-rod, without the lalt or fmallelt 
joint. From the extremity of this rod proceeds a {lender 
glafs tube c, covered with fealing-wax, and having a cork 
d at its end, from wdrich a pith-ball electrometer is fuf- 
pended. hgi is a piece 'of twine faftened to the other 
extremity of the rod, and fupported at g by a frnall firing 
fg. At the end i of the twine a pin is faftened, which, 
when puflred into the cork d, renders the electrometer e 
uninfulated. 
When 
