Influence Machines

Influence Machines, in electricity, are machines for the separation of electricity on a large scale. The best known is the Wimshurst machine, which works on the principle of electric induction.

It consists of two circular plates of glass or ebonite placed close together and made to rotate in opposite directions on the same axis. On the outer face of each plate small radial discs of tinfoil are fixed, in number from ten t'o eighteen usually. Tracing the course of one such disc suffices to explain the course of all. It has at one moment a small positive charge, and induces a negative charge on the disc facing it and passing round on the opposite plate in the reverse direction. After performing this induction the given disc discharges itself into one receiver by means of a small metallic brush, and, travelling round further, is charged negatively by induction from a disc on the other plate. It then does duty in acting inductively for the production of a positive charge, and is then discharged into a receiver that collects the negative charges. Being then charged positively, it is in the primary condition of the cycle of changes, and the process is repeated. Positive charges accumulate on one receiver, and negative charges on the other. [Electricity.]