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. *

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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.