Wimshurst

The Wimshurst machine is a two-disk electrostatic generator invented by James Wimshurst in the 1880s. It produces high voltages by induction using two contra-rotating insulating disks with metal sectors, neutralizing bars with brushes, and collector combs, typically connected to Leyden jars for storing charge. The design is a classic example of an influence machine.

In operation, each glass disk carries a pattern of metal sectors arranged around its surface. The disks rotate in opposite directions, driven by a hand crank or motor. Neutralizer bars with brushes traverse the disks and transfer charge between sectors on opposite disks, helping to polarize and multiply the charges. Collector combs adjacent to the disk surfaces collect the accumulated charge and channel it into a high-voltage reservoir, such as Leyden jars. A spark gap or other discharge device provides a visible discharge path when the voltage becomes sufficiently high.

History and significance: James Wimshurst and his collaborators developed the machine in the late 19th century as an improvement on earlier influence machines. It became a standard demonstration device in physics laboratories and contributed to studies of electrostatics and electrical discharge during that era.

Design notes: typical features include two neutralizing bars on opposite sides of the disks, adjustable collector combs, a discharge spark gap, and Leyden jars for storage. Some models include enhancements such as additional discharge controls or auxiliary condensers. The device operates best in dry conditions to minimize leakage.

Today the Wimshurst machine is mainly used for educational demonstrations and historical appreciation, with modern high-voltage equipment largely superseding its practical use.