00:00Mechanical devices that harness the energy of wind were used as early as in ancient Persia, in the 9th or 10th century.
00:09The most advanced form of windmill was developed in the Netherlands in the 17th century.
00:14Windmills were typically built on natural or artificial elevations, where the wind flow was undisturbed.
00:20Dutch windmills were usually built of wood, adobe, bricks, or stone.
00:25Their conical roof provided lower air resistance.
00:29The roof or cap was placed on a movable mechanism that allowed it to be rotated so that the sails always face the wind.
00:36The internal space of a windmill usually consisted of a few, usually three, floors.
00:42The cap housed the brake wheel, one of the most important components of the mechanism.
00:48The aerodynamic force that arose on the sails was converted into the rotary motion of the wind shaft.
00:54The brake wheel, connected to the wind shaft, transmitted its rotation to the upright shaft.
01:00The upright shaft drove three axles through transmissions of the great spur wheel and the stone nuts.
01:07The axles drove the millstones, which were placed on the second floor, also called the stone floor.
01:13The millstones were part of the windmill that ground the wheat or other grains.
01:17They were covered with a casing made of stone or wood.
01:20The flour was then transferred to flour chests, placed on the bottom floor through pipes.
01:26The bags of flour were moved between the floors by mechanical lifting devices, while workers used ladders.
01:33Windmills were once commonly used throughout Europe, but their importance declined at the time of the Industrial Revolution.
01:39Many windmills have recently been restored for their historical value.
01:44Of the 10,000 windmills in use in the Netherlands in the 19th century, about 1,000 are still standing.
Comments