Windmills are engines powered by wind which produce energy. The energy produced can power mechanics to grind, pump, saw or hammer. Modern machines, known as wind turbines, are used to generate electricity.


Windmills receive motion from the impulse of the wind. The structure of windmill is a conical or pyramidal tower of considerable height, with a conical or hemispherical dome. There are two kinds of windmills, the vertical and horizontal. In the former, the wind is made to act upon sails or vanes, generally four in number, attached by means of rectangular frames to the extremities of the principal axis or wind-shaft of the mill, ulii.ii is placed nearly horizontal, Bo that the sails, by the action of the wind, revolve in a plane nearly vertical, giving a rotatory motion to the driving-wheel fixed to the wind-shaft, and thus conveying motion to the vertical shaft and the machinery connected with it.

The extremity of the wind-shaft must always be placed so as to point to the quarter from which the wind blows,. To effect this some mills have a self-adjusting cap, which is turned round by the force of the wind acting upon the fan or flyer, attached to the projecting framework at the back of the cap. The Windmill-cap is the movable upper part of a windmill which turns to present the sails in the direction of the wind.

By means of a pinion on its axis, motion is given to the Inclined shaft and to the wheel on the vertical spindle of the pinion a, this latter pinion engages the cogs on the outside of the fixed rim of the cap; by these means the ftails are kept constantly turned to the wind, the head of the mill moving slowly round the moment any change in the direction of the wind causes the fan to revolve. In the horizontal windmill the wind-shaft is vertical, so that the sails revolve in a horizontal plane. The effect of horizontal windmills, however, is considered to be far inferior to that of the vertical kind. The effect of windmills depends greatly upon the form and position of the sails.

Large examples

  • Post Windmill
  • Smock Windmill
  • Tower Windmill

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