90 degrees. The angular setting of the bars may be altered between about 60 and 90 degrees, so as to get the most efficient condition of working. In addition to the two bars with their four brushes, there are the two devices for collecting the electricities of opposite sign. Each consists of a U-shaped rod, the limbs of the U embracing the pair of discs from the outside and being provided with a "comb" of sharp points before which the sectors pass. The collecting combs are set on a horizontal line. The direction of rotation of each disc is such that a particular sector, having just passed a comb, turns through an acute angle in order to reach the brush on the cross bar on the same side.
Fig. 5 is a diagrammatic representation of the Wimshurst machine, but for the sake of greater clearness I have substituted concentric cylinders for the parallel discs. The direction of rotation is shown by the arrows. Let the inner cylinder represent the front disc, and the outer the disc at the back. The discs themselves are not shown, only the segments which are represented by the short lines. The cross bar for the front disc is shown by a straight line, that for the back disc by a curved line. This is done merely to
