Boys and girls have flown kites as toys for many years. No one knows who invented the kite. We do know that a flat kite had been used in China for more than 2,000 years. Kites have meant a great deal to the people of China, Japan, and Korea. Not only boys and girls but also grown people fly kites for fun there. Some of their kites, are gaily decorated. The Chinese enjoyed flying kites so much that the ninth day of their ninth month was made Kites' Day and is still a great holiday.

   But kites have been much used for other things besides toys. The ancient Chinese flew kites above their houses to drive evil spirits away. Armies formerly used kites in sending signals from one place to another. Big suspension bridges have been started from lines carried across deep valleys by kites. And weather bureaus have sent weather instruments high into the air by using kites.

   A kite played an important part in one very famous experiment. Benjamin Franklin used a kite in finding out that lightning is a great spark of electricity.

   The United States Weather Bureau succeeded in making kites carry weather instruments more than four miles above the earth. To reach such great heights they used a train made up of several kites.

   Strings are attached to kites so as to hold them at a slant. The wind pushes against the undersurface and at the same time rushes around the edges of the kite and drags some of the air from the upper side. It creates what scientists call a partial vacuum there. The push of the air on the underside is much greater than the push on the upper side and the kite is held in the air. It is held up in the same way that an airplane is held up. The difference is that an airplane has to keep moving rapidly through the air to make the pressure above and below its wings different, while a kite depends on the wind to do this.

   Although wind is needed for kite flying, the best kite-flying days are not the days when there are strong winds. The best days are those with a gentle breeze.