62 ‘ PHILOSOPHICAL SOCIETY OF WASHINGTON. 
Let us now move the particle to the surface of the cylinder, then 
we have d= 7; a= 7/4r* +17; b =h, and (6) becomes 
ah 
A’ = 2m0 —- (F— E). (6’) 
Mr. Woodward, as already stated, had found an infinite attrac- 
tion of a circular disc on a particle on its circumference by using 
Price’s method. Now, since A’ is surely a finite quantity, we have 
here the manifest absurdity that the attraction of a cylinder on a 
particle on its surface would be’ less than that of a circular disk 
which is only an infinitesimal part of it. 
If we wish to ascertain the attraction of a circular disk of finite 
small thickness we may, of course, use (6’), and since then F’ tends 
to infinity, E may be neglected; therefore 
- d 
A’ _ 2mé ah f = 
are Nats af — sin? 
) 7 ae h=o0 
oy 
= 4m0 
i 
h? h=o 
me 
47? af sin *9 dg 
a* Ag® 
= 4m - 
Th h=o0 
= 0 - 
Since then the attraction is 0 if A = 0 it will be small if h is 
small, and will continuously grow with h. 
