A Wimshurst Machine
The Wimshurst Machine consists of two varnished glass plates revolving in opposite directions. On the outside of each of these plates are cemented a number of tinfoil "sectors," arranged radially. Two conductors at right angles to each other extend obliquely across the plates, one at the back and the other at the front. These conductors each terminate in brushes of tinsel which electrically excite the "sectors" as the plates revolve. The electricity is collected by a set of "collectors" arranged in a somewhat similar manner to the collector on the cylinder electric machine.
The Glass Plates are each eighteen inches in diameter. Purchase two panes of clear glass twenty inches square from a glass dealer. The white glass is far preferable to the green glass and will make the best electric machine. The plates should be of the thickness known as "single light" and should be perfectly free from wavy places, bubbles, or other imperfections.
Fig. 34.—Paper Pattern for laying out the Plates.
The work is first laid out on a piece of stiff paper twenty inches square as a pattern. Describe a circle four inches in diameter. Using the same center, draw other circles, making them respectively eight, sixteen, and eighteen inches in diameter. Then mark sixteen radial lines, from the center, making them equal distances apart, as shown in Figure 34.
Fig. 35.—Plate with Sectors in Position, and a Pattern for the Sectors.
Lay one of the glass panes over the pattern and cut out a glass circle eighteen inches in diameter, or perhaps you may be able to have a glazier do the cutting for you and so save considerable trouble and possible breakage. Two such plates should be made.
The Sectors are cut from heavy flat tinfoil according to the pattern shown in Figure 35. They should be made one inch and one-half wide at the wide end and three-quarters of an inch at the other end. They are each four inches long. Thirty-two such sectors are required. The easiest way to make them is to cut out a pattern from heavy cardboard to serve as a guide.