1 88 Mr. Read’s Meteorological Journal 
tively ; but, if the balls open wider, I write they are electrified 
negatively ; and the reverfe when I ufe fealing-wax. When 
the balls diverge one inch and upwards, vifible fparks may be 
drawn at the brafs ball L. When fparks are faid to have been 
perceived in any obfervation, I have generally on that account 
omitted to note the variable quantities of divergency in the 
pith balls. Their utmoft limit of regular divergency feems to 
be about five or near fix inches ; above that they are unfteady 
and diforderly. The pith balls are near two-tenths of an inch 
in diameter, fufpended by very fine flaxen threads (in the ftate 
it is in from the heckle) five inches long. When I mention 
the diftance of the balls in tenths of an inch, it is to be un- 
derftood as nearly fo as my eye can determine. 
This apparatus requires a conftant attention, efpecially during 
a difturbed ftate of the atmofphere. From the room in which 
the apparatus is placed 1 am feldom abfent one hour, excepting 
the time of fleep ; but, when I leave it, the laft thing I do at 
night is to examine the ftate of the eleCtricity, and, if I find 
the rod uneleCtrified, I then place the Leyden bottle on the 
table P, with its knob nearly in contact with the ball L. The 
next morning, if I find this bottle charged, I write the kind of 
eleCtricity it is charged with againft the day in the journal, and 
add, by the night bottle . 
It is prefumed, that the table is fufficiently obvious. The 
two columns for pofitive and negative eleCtricity are ufed only 
for the firft obfervation of each day. I ufe Fahrenheit’s 
thermometer, fufpended on the north outfide of a bow win- 
dow. The time of making the obfervation with it, and the 
barometer, and alfo of the direction of the wind, has ufually 
been about nine o’clock in the morning. 
Laftly, it may be ufeful to obferve, that I have always 
found the lower though uninfulated part of the apparatus (viz, 
3 the 
