- published: 30 Mar 2014
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A windmill is a machine which converts the energy of wind into rotational energy by means of vanes called sails or blades. Originally windmills were developed for milling grain for food production. In the course of history the windmill was adapted to many other industrial uses. An important non-milling use is to pump water, either for land drainage or to extract groundwater with windpumps. Windmills used for generating electricity are commonly known as wind turbines.
The windwheel of the Greek engineer Heron of Alexandria in the 1st century AD is the earliest known instance of using a wind-driven wheel to power a machine. Another early example of a wind-driven wheel was the prayer wheel, which was used in ancient Tibet and China since the 4th century. It has been claimed that the Babylonian emperor Hammurabi planned to use wind power for his ambitious irrigation project in the 17th century BC.
The first practical windmills had sails that rotated in a horizontal plane, around a vertical axis. According to Ahmad Y. al-Hassan, these panemone windmills were invented in eastern Persia as recorded by the Persian geographer Estakhri in the 9th century. The authenticity of an earlier anecdote of a windmill involving the second caliph Umar (AD 634–644) is questioned on the grounds that it appears in a 10th-century document. Made of six to twelve sails covered in reed matting or cloth material, these windmills were used to grind grain or draw up water, and were quite different from the later European vertical windmills. Windmills were in widespread use across the Middle East and Central Asia, and later spread to China and India from there.
I spend too much time raiding windmills
We go side by side laughing until it?s right
There?s something that you won?t show
Waiting where the light goes
Take the darkest hour break it open
Water to repair what we have broken
There?s something that you won?t show
Waiting where the light goes
Maybe anywhere the wind blows
It?s all worth waiting for
Pull on the borders to lighten the load
Tell all the passengers we?re going home
I spend too much time seeking shelter
World without end couldn?t hold her
There?s something that you won?t show
Waiting where the light goes
And anyway the wind blows
It?s all worth waiting for