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7/29/2019 A History of Windmills
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A History of Windmills
* A windmill is a machine which converts wind energy into rotational energy. It does this by using
sails or blades. Originally windmills were made for milling grain. Later the windmill was adapted for
other industrial uses.
* The earliest known windmill was designed by the Greek engineer, Heron of Alexandria in the first
century AD.
* The first practical windmills had sails that rotated around a vertical axis. They were invented in
eastern Persia in the ninth century. These windmills were made of six to twelve sails covered in reed
matting or cloth material. They were used to grind grain or draw up water. They were in use across
the Middle East and Central Asia, and later spread to China and India. Horizontal windmills were also
built in Europe during the eighteenth and nineteenth centuries. * This is Hooper's Mill in Margate,
Kent.
* The earliest type of European windmill was the post mill. Its sails rotated around a horizontal axis,
unlike the ones from the Middle East. It was named the post mill because of the large upright post
on which the mill's main structure is balanced. By mounting the body this way, the mill is able to
rotate to face the wind direction. This was essential for windmills to operate economically in North-
Western Europe, where wind directions are variable.
* By the end of the thirteenth century the tower mill had been introduced. Only the cap of the tower
mill is rotated rather than the whole body of the mill. Tower mills are also found around the
Mediterranean Sea but they have a fixed cap. They are built with the sails facing the prevailing wind
direction.
* The smock mill is an improvement of the tower mill where the tower is made of a wooden
framework, called the "smock." The smock is usually octagonal. The smock is thatched, boarded or
covered by other materials.
* Windpumps are used extensively on farms in the central plains of the United States and in
Southern Africa and Australia. The windpump was invented by Daniel Halladay in 1854. At their peak
in 1930, an estimated 600 000 windpumps were in use.
* A windmill used to generate electricity is called a wind turbine. The first turbines were built during
the 19th century by Professor James Blyth in Scotland. As the twenty-first century began, concernsover global warming and fossil fuel depletion led to an interest in all available forms of renewable
energy. Worldwide there are now many thousands of wind turbines. *
7/29/2019 A History of Windmills
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n Geskiedenis van Windmeulens
n Windmeul is n masjien bekeer wind-energie aan rotasie-energie. Die windmeul bekeer dit met
seile of lemme. Windmeulens was oorspronklik om maal te graan.Dit was later vir ander industrile
gebruike aangepas.
Die vroegste bekende windmeul was ontwerp deur die Griekse ingenieur, Heron van Alexandria in
die eerste eeu n Christus.
Die eerste praktiese windmeulens het seile wat oor 'n horisontale as draai. Hulle was in ooste Persi
in die negende eeu uitgevind. Hierdie windmeulens het ses tot twaalf seile bedek met riet mat of lap
materiaal.