Static electricity and lightning are the same thing. A boy can produce static electricity in small quantities by rubbing a glass rod with a piece of flannel or silk. [Illustration: FIG. 1.—A simple Wimshurst Machine which any boy can easily make. P P, Plates; BR, Neutralizes; C R, Collectors; DR, Discharge Rods; J J, Leyden Jars; H H, Insulating Handles; C, Crank; U, Upright; B, Belt.] Rub the rod briskly and then hold it over some tiny bits of paper or specks of dust and watch them jump up to meet the rod, just as if the latter were a magnet attracting small tacks or nails. It is static electricity which gives the rod this wonderful power. If you rub the rod briskly and then hold it close to your cheek, you will feel a slight tickling and hear a faint crackling sound. If this is done in the dark you may be able to see a very faint phosphorescent light or even small sparks. The quantity of electricity produced in this manner by rubbing a glass rod is extremely limited and while a number of very interesting and instructive experiments may be performed in this manner, the most spectacular ones are only possible with the aid of a "static-machine". [Illustration: FIG. 2.—The plates for the Static Machine are made of hard rubber and are 7 inches in diameter. Each plate carries sixteen tinfoil sectors.] The most practical form of static machine is that known as the "Wimshurst". It consists of two circular plates made of glass or hard rubber arranged so that by turning a crank, they may be revolved in opposite directions. On these plates are a number of small strips of tinfoil. The static electricity is generated on these tinfoil strips and collected by two metal rods having small pins arranged along them in a row. A simple form of Wimshurst machine which any boy can easily make is illustrated in Figure 1. It will generate considerable static electricity and will make sparks two inches long. *The Plates* on these machines are hard rubber. They are illustrated in Figure 2. Glass is usually used for static machine plates, but has the disadvantage of breaking easily. It is also hard for the young experimenter to cut out circular glass plates and drill them. The author has had very good success with hard rubber. [Illustration: FIG. 3.—The details of the Tinfoil Sector. Sixteen are required for each plate. They are stuck to the plates with shellac.] Two plates are required for the machine. They should be in the form of circles seven inches in diameter and be perfectly true. They need to be only one-sixteenth of an inch thick. The rubber should be perfectly flat and not warped at any point. *The Sectors*, as the tinfoil strips are called, are wedge shaped pieces having rounded ends as shown in Figure 3. They should be cut of heavy tinfoil. Thirty-two sectors are required, sixteen for each plate. They are seven-sixteenths of an inch wide at the top, one inch long and five-sixteenth of an inch wide at the bottom.