Windmills are incredibly ingenious devices that are able to convert wind power into useful mechanical work. This is achieved by using large ‘sails’, usually made of wood, imparts rotational force to the main shaft that in turn can be used to power a process, like grinding flour.
The Persians were some of the first people to harness the power of wind when they began building early forms of windmills in Iran and Afghanistan in around the 7th Century AD.
These early windmills consisted of sails radiating from a vertical axis within a building with two large openings for the inlet and outlet of wind diametrically opposite each other. The mills were used to directly drive single pairs of millstones without the use of gears.
They were one of the first means by which civilizations were able to directly replace human beings as the main source of power for a process.
Windmills would become increasingly widespread throughout Europe during the Middle Ages and stayed in use well into the 19th Century.
The development of steam power during the industrial revolution would spark the eventual decline of windmills.