The windmill is a simple device used over the years for many valuable purposes: grinding grain, driving saws, pumping water, driving electric generators, and charging storage batteries. The windmill harnesses natural wind energy for human use--the whirling propeller shaft transmits its rotary motion through gears, converting it into power that people can use.

Windmills go far back in history. Nearly 4,000 years ago the Babylonian emperor Hammurabi (1792-1750 B.C.) used them for irrigation. About 200 years before Christ, Hero of Alexandria described a windmill in his writings. By 1000 A.D. these machines were in practical usage throughout Europe. In 1105 a French convent built both a water mill and a windmill.

It was the Dutch who made the most extensive use of windmills. Inhabitants of the Netherlands faced a drainage problem for centuries. Their land was actually a series of marshes separated from the...