Wind Mill

A windmill is a machine that converts the energy of wind into rotational energy by means of vanes called sails.[1][2] Originally, windmills were developed for milling grain for food production. In the course of history, the windmill machinery was adapted to many other industrial uses.[3] An important non-milling use is to pump water, either for land drainage or to extract groundwater. Contents [hide] * 1 Windmills in antiquity * 2 Horizontal windmills * 3 Vertical windmills * 3.1 Post mill * 3.2 Hollow-post mill * 3.3 Tower mill * 3.4 Smock mill * 3.5 Sails * 3.6 Machinery * 3.7 Spread and decline * 4 Windpumps * 5 Wind turbine * 6 See also * 7 References * 8 Further reading * 9 External links |
-------------------------------------------------
Windmills in antiquity

Heron's wind-powered organ
The windwheel of the Greek engineer Heron of Alexandria in the first century AD is the earliest known instance of using a wind-driven wheel to power a machine.[4][5] Another early example of a wind-driven wheel was the prayer wheel, which was used in ancient Tibet and China since the fourth century.[6] It has been claimed that the Babylonian emperor Hammurabi planned to use wind power for his ambitious irrigation project in the 17th century BC.[7]
-------------------------------------------------
Horizontal windmills

The Persian horizontal windmill

Hooper's Mill, Margate, Kent, an 18th-century European horizontal windmill
The first practical windmills had sails that rotated in a horizontal plane, around a vertical axis.[8] According to Ahmad Y. al-Hassan, these panemone windmills were invented in eastern Persia as recorded by thePersian geographer Estakhri in the 9th century.[9][10] 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.[11] Made of six to 12 sails covered in reed matting