110 On the Generation of Statical Electricity. 
nected by across piece, furnish supports to the axis which turns 
between the glass pillars; these are placed one inch apart. 
The rubbers (C) (C’) have glass backs one inch broad, and one 
and a half inches deep, and are about two feet long, moving be- 
tween the glass pillars, which, by means of brass caps or sockets 
and screws, cause the rubbers to maintain the proper degree of 
pressure. af 
The positive prime conductor (P)(P), is composed of tw 
branches, one on each side of the cylinder, each of which is four 
inches in diameter, and three feet long; these are joined at their 
farther extremities by a cross tube of two inches in diameter, 
which has a branch one inch in diameter, and six inches long, 
terminated by a ball two inches in diameter. The cross piece 
should be movable in the sockets of the prime conductor. 
The negative prime conductor (N) (N) is four inches in diame- 
ter, and three feet six inches long, supported by the two pairs of 
glass pillars; it is connected to the top rubber by means of a 
brass rod (R) one half inch in diameter, which is loosely insert- 
ed in a hole in the rubber which communicates with the amal- 
gam. ‘The rod can be withdrawn, and by this means the upper 
conductor becomes insulated from the rubber, and may be con- 
nected to the positive prime conductor, of which it will then 
form a part. The latter conductor is supported by four glass pil- 
lars, (G)(G)(G)(G), eighteen inches long each. The amalgam 
of the lower rubber communicates with a Leyden jar or the ta- 
ble by a chain or wire (W), which also is connected to the upper 
rubber when the negative electricity is not wanted.* The crank 
(T) gives the motion to the cylinder. The many advantages of 
a machine arranged in this manner become evident on reflection ; 
it is sufficient in this place to observe, that if made after the 
manner directed, it will equal in power two large plate machines 
(the diameter of each plate being three feet) constructed after the 
common method, and using the ordinary rubbers. 
Prime Conpuctors.—Having already extended this paper be- 
yond the original intention, the remainder of the subject will be 
concisely treated. Prime conductors of the ordinary form should 
be of such size as to hold on their surfaces electricity of the same 
* By applying a detached row of points communicating with the ground, and 
near to the glass between (A) and (C), both conductors will be charged at the 
same time,—one with positive and the other with negative electricity. 
