Introduction of Wind Power
During the reign of Caliph Ummar (634-44) began the use of wind as a source of power in Islam. A Persian came to the Caliph and said he could build a mill operated by wind, so the Caliph ordered him to have one built. Wind-power became widely used in Islam to run mill stones for grinding corn, and also to draw up water for irrigation. Descriptions and drawings of Islamic windmills exist in a large abundance.
`A millstone is attached to the end of a wooden cylinder, half a metre wide, and 3.5 to 4 metres high, standing vertically in a tower open on the north east side to catch the wind blowing from this direction. The cylinder has sails made of bundles of ush or palm leaves (which reminds of the modern European windmill), attached to the shaft of the axle. The wind, blowing into the tower, exerts strong pressure on the sails, so turning the shaft and millstone.'
The windmills were erected on substructures built for the purpose, or on the tower of castles or on hilltops. Early windmills for grinding corn were, indeed, two storey buildings; in the upper storey were placed the millstones, and in the lower one, a wheel driven by the sails-six or twelve in number and covered with fabric-which turned the upper millstone. The walls of the lower chamber were pierced by four vents with the narrower end towards the interior, like the loopholes of a fortress so as to direct the wind on to the sails, and increase its speed.
In Europe, the oldest text in relation to windmills is a French act of 1105 granting a religious community the right to establish one of these apparatuses, called molendinam ad ventum (moulin a vent in French: windmill in English).
by: FSTC Limited, Fri 10 January, 2003