[ ^59 ] 
Thcfe two laft cafes are experiments of Mr. Can- 
ton’s, and are defcribed in Philof. Tranf. 1753, p. 350, 
where are other experiments of the fame kind, all 
-readily explicable by the foregoing theory. 
I have now confidered alkthe principal or funda.- 
-mental cafes of ele(^ric attradions and repulfions 
which I can think ofj all of which appear to agree 
perfedly with the theory. 'A • , 
§ 3* cales in which bodies receive elec- 
tricity from or part with it tp the air. 
Lemma I. 
Let the body A (fig. 6.) either fland near fome 
over or undercharged body, or at a di dance from any. 
It feems highly probable, that if any part of its fur- 
face, as M N, is overcharged, the fluid will enr 
deavour to run out through that part, provided the 
air adjacent thereto is not overcharged. 
For let Q be any point in that furface, and P a 
point within the body, extremely near to it; it is 
plain that a particle of fluid at P, mufl; be repelled 
with as much force in one diredion as another 
(otherwhfe it could not be at reft) unlefs all the fluid 
between P and G is prefled clofe together, in which 
cafe it may be repelled with more force towards G 
^han it is in the contrary diredion ; now a particle at 
G is repelled in the diredion PG, /. e. from P to G, 
by all the redundant fluid between P and G; and a 
particle at P is repelled by the fame fluid in the con- 
trary diredion ; fo that as the particle at P is repdied 
with not lels force in the diredion P G than in the 
’ ’ ' 4 P 2 contrary, 
