[ 7 6 3 ] 
tity of the lightning is drawn off, equal to the quan- 
tity which was contained in that atmofphere, and no 
longer. For then the lemi-diameter of the atmof- 
phere being reduced to 60 feet, every part of it is 
above, and not in contad with, the fharp point (a), 
and confequently beyond its fphere of adion. But 
let the fharp point be then advanced into the atmo- 
fphere By and it will ad as before, &c. 
The truth of this, however contradidory it may 
be, to the general opinion of the adion of fharp 
points, in drawing off the eledricity or lightning *, 
may be illuftrated by the following experiment on 
the prime-condudor. Eledrify the prime- conduc- 
tor in a dark room, and draw back the globe to a 
fufficient diffance from the prime-condudor, to pre- 
vent its being fupplied with any more eledricity from 
the globe, while you are taking off* the eledrical 
atmofphere with a fharp point. Bring then a fharp 
point, either vertically or horizontally, or in any 
other diredion, within two feet of the prime-con- 
dudor ; and the point, for fome time, will appear 
luminous. After that light difappears, advance the 
point three or four inches nearer to the condudor, 
and you will obferve the fame phenomena as before ; 
and by advancing the point gradually in this manner, 
as the light upon it difappears, the point will be al- 
ternately luminous and dark, till you have taken off 
the whole atmofphere in different laminas. As the 
* Mr. Franklin fays, fpeaking of fharp points, “ At whatever 
<c diftance you fee the light, you may draw off the electrical 
“ fire.” page ii. 
5 D 2 
point 
