[Illustration: THE KITE-BUOY IN SERVICE.] It is best to make rain-kites of oil-skin or paraffine paper, as the ordinary paper or cloth becomes saturated with the dampness and very heavy, thus lessening the buoyancy of the line. So penetrating is the dampness of clouds, even without a rain-storm, that the wooden frames sometimes become warped and the paste seams soak open. DRAWING DOWN ELECTRICITY BY A KITE-STRING. The scientific kite-flyer will find much to tempt him into the field of electricity; and will be able, not only to duplicate Dr. Franklin's historic experiment of bringing down sparks from the heavens, but may go far beyond this, taking advantage of the greater knowledge of electricity at his disposal and the superior apparatus. In the summer of 1885, Alexander McAdie, at the Blue Hills Observatory, got strong sparks at the earth's surface from a wire connected with a kite whose surface had been coated with tinfoil so as to form an electric collector. He also, by the brightness and increased lengths of the sparks obtained, proved that the electric force in the atmosphere is very greatly increased with the approach of thunder clouds; and also that this force increases steadily as the kites reach greater altitude, and _vice versa_. Indeed Mr. Eddy and others who have conducted similar experiments, have found the electric force so strong at certain altitudes as to make the manipulation of the conducting wire a source of considerable danger. On October 8, 1892, Mr. Eddy made an important advance in electrical experiments with kites, by using a collector quite separate from the kites themselves, which were merely used in tandem to support the line on which the collector was swung and raised to any desired altitude. By this arrangement any accident that might befall one of the kites is less likely to ruin the whole experiment.