A windmill is a type of working engine. It converts the wind's energy into rotational energy. To do this it uses vanes called sails or blades.

The energy made by windmills can be used in many ways. These include grinding grain or spices, pumping water and sawing wood. Modern wind power machines are used to create electricity. These are called wind turbines by engineers or wind mills by the average person. Before modern times, windmills were most commonly used to grind grain into flour for making bread. The windmill has been in history for many years.

History 

An organ powered by a windwheel was written about in the 2nd century AD by the Greek engineer Hero. It could have been the first machine in history that used wind power. Vertical axle windmills were used in eastern Persia (Sistar) by 60 AD. Horizontal axle windmills were invented in Northwestern Europe in the 1180s. This is the type often used today.

Early history 
The first windmills had long vertical shafts with rectangle shaped blades. They existed in Persia in the 9th century. There is a story about a windmill and the second caliph Umar (634\644 AD). It is not known if this is a true story. These windmills were made of six to twelve sails. The sails were covered in reed matting or cloth. They were very different from European versions. A similar type of vertical shaft windmill with rectangle blades can also be found in 13th century China. They were used for irrigation.

How they work

The blades or sails of the windmill are turned by the wind. Gears and cogs makes the drive shaft inside the windmill turn. In a windmill used for making flour, this turns the grinding stones. As the stones turn, they crush the wheat (or other grain) between them. In a windmill used for pumping water, turning the drive shaft moves a piston. The piston can suck up and push out water as it moves up and down. In a windmill used for generating power, the drive shaft is connected to many gears. This increases the speed and is used to turn a generator to make electricity.

Windmills in culture and literature 

Miguel de Cervantes' book Don Quixote de La Mancha has an important scene in which Don Quixote attacks windmills. He thinks that they are violent giants. Because of this, La Mancha and its windmills are famous. This is also the origin of the phrase "tilting at windmills". It means an act of uselessness.  "Moulin Rouge" translated directly from French, and means Red Windmill.

Gallery

Related pages 
 Renewable energy
 Renewable resource
 Land reclamation
 Watermill

Footnotes

Further reading 
 A.G. Drachmann: "Heron's Windmill," Centaurus, 7 (1961), pp. 145–151
 Hugh Pembroke Vowles: "An Enquiry into Origins of the Windmill", Journal of the Newcomen Society, Vol. 11 (1930-31)

Other website 

 Windmills at Windmill World
 The International Molinological Society (TIMS)
 All About The American Water Pumping Windmill
 Norfolk Mills
 Britannica
 1st English Post Windmill, Virginia
 Poldaw Windpumps , intended principally for applications in developing countries.

History links 
 Windmillers' Gazette
 History of the Traditional American Farm Windmill
 windmillworld: history
 American Wind Power Center - An American water pumping windmill museum in Lubbock, Texas USA.
 Shattuck Windmill Museum Thirty-nine water pumping windmills used on the plains; in Shattuck, Oklahoma
 Illinois Windmills—history and archives for the Dutch windmills in the state.

Theory
 Wind Power and Windmills

Tools
Wind energy