An apparatus for development of high tension electricity by contact
action, brought about by friction.

It consists of a plate or cylinder of glass mounted on insulating
standards and provided with a handle for turning it. One or more
cushions of leather are held on an insulated support, so as to rub
against the plate or cylinder as it is turned. A metal comb or combs are
held on another insulating support so as to be nearly in contact with
the surface of the glass plate at a point as far removed as possible
from the rubbers. The combs are attached to a brass ball or round-ended
cylinder, which is termed the prime conductor.

In use either the prime conductor or cushions are connected by a chain
or otherwise with the earth. Assume it to be the cushions. As the
machine is worked by turning the plate, the glass and cushion being in
contact develop opposite electricities. The glass is charged with
positive electricity, and as it turns carries it off and as it reaches
the prime conductor by induction and conduction robs it of its negative
electricity. Meanwhile the cushions negatively excited deliver their
charge to the earth. The action thus goes on, the prime conductor being
charged with positive electricity.

If the prime conductor is connected to the earth and the cushions are
left insulated, negative electricity can be collected from the cushions.

In some machines both prime conductor and cushions are kept insulated
and without ground contact. Electrodes connecting with each are brought
with their ends close enough to maintain a sparking discharge.