50 Fun Facts About Windmills

In which country did the first practical windmills, with horizontally turning sails, appear around the 9th century?

The geographer Estakhri reported them in Khorasan; they had six to twelve reed-covered sails turning round a vertical shaft.

What was the early Persian windmill with lightweight vertical sails on a vertical shaft called?

It was first built to pump water and only later adapted to grind grain.

Which Babylonian ruler is said to have used wind power for irrigation as early as the 17th century BC?

Hero of Alexandria later described a wind-driven wheel powering an organ, though it may only have been a toy or a design idea.

In which triangle of regions did the vertical windmill first appear in the 12th century?

It is unclear whether it owed anything to the Persian horizontal mills that had reached southern Europe a century earlier.

Northern Europe's earliest certain windmill reference, from 1185, comes from a village in which English county?

Weedley stood at the southern tip of the Wolds overlooking the Humber; these first mills ground cereals.

What is the earliest European windmill, whose whole body turns on a large upright timber?

The first ones were 'sunken', with the post buried in a mound; later a trestle, often enclosed in a roundhouse, held it up.

In a tower mill, which part rotates to face the wind?

Because the masonry tower stays put it can be built taller with longer sails, useful even in light winds; it arrived by the end of the 13th century.

What is the small windmill behind the sails that turns a mill's cap into the wind automatically?

Fantails are common in Britain, Denmark and Germany but rare elsewhere; around the Mediterranean some mills had fixed caps because the wind hardly varied.

A smock mill replaces the masonry tower with what?

The Dutch introduced them in the 17th century because they were light enough to stand on soft, wet ground; the name comes from a peasant's smock.

What was the purpose of the hollow-post mills used in the Netherlands from the early 15th century?

The hollowed post let a drive shaft pass down to machinery below while the body still turned into the wind.

Who invented the self-regulating 'patent sails' of connected shutters in 1807?

Before that, the mill had to be stopped so the miller could spread more or less sailcloth over the lattice frames.

How many sails do the majority of windmills have?

Five-, six- and eight-sailed mills were built especially in Lincolnshire and Yorkshire; even numbers let a mill run with a broken sail by removing its opposite too.

In the Netherlands, what does it mean when the sails are stopped in a '+' shape (3, 6, 9 and 12 o'clock)?

An 'X' means closed; a slight tilt with the top blade at 1 o'clock signals joy, and a tilt to 11-2-5-8 signals mourning or warning.

Dutch windmills were set in the mourning position nationwide in 2014 to honour victims of what?

The same signals were used to warn neighbours during Nazi searches in the Second World War.

Inside a windmill, what is the horizontal gearwheel atop the upright shaft, driven by the brake wheel, called?

Lower down, the great spur wheel drives the stone nuts that turn each millstone.

What is the horizontal shaft that carries the sails called?

It could be all wood, wood with a cast-iron pole end, or all cast iron, with the brake wheel fitted between its bearings.

In a pair of millstones, what is the stationary lower stone called?

The concave-rimmed runner turns on top of it, creating a scissoring action that grinds the grain.

Roughly how many wind-powered mills were there in Europe at their peak in 1850?

That was about half the number of water wheels; wind was used where water was scarce, froze in winter or flowed too slowly.

Of the roughly 10,000 windmills working in the Netherlands around 1850, how many still stand?

Most are run by volunteers, and many drainage mills serve as backup to modern pumping stations.

Which Dutch area, with about 600 windmill industries by the late 1700s, is called the first industrialised region?

Its mills sawed timber and processed oil, paint and paper; the Zaanse Schans museum preserves some today.

How many windmills were built around 1740 to drain the Alblasserwaard polder at Kinderdijk?

It is the largest concentration of old mills in the Netherlands and has been a UNESCO World Heritage Site since 1997.

In which year did the Kinderdijk windmills become a UNESCO World Heritage Site?

The name means 'children's dike'; today two diesel pumping stations do most of the real draining.

What is the Zaanse Schans, near Zaandam?

Two of its mills are still on their original sites; the rest were moved there for preservation.

In which novel does the hero attack windmills he believes to be giants?

Cervantes' scene gave English the idiom 'tilting at windmills' for attacking imaginary enemies.

What does the idiom 'tilting at windmills' mean?

The town of Consuegra in La Mancha still has a hilltop line of windmills beside its castle.

Which Paris cabaret, founded in 1889, has a landmark red windmill on its roof?

Its name means 'red mill'; it stands on the Boulevard de Clichy below Montmartre, once a hill of real mills.

What was the Oude Molen, completed in 1718?

Early tower mills had not survived the Cape's gales, so the Dutch East India Company's Heeren XVII sent out builders and materials.

Who invented the self-regulating American farm windpump in 1854?

On the Great Plains, windpumps drew water from wells for cattle.

Where was the first electricity-generating wind turbine shown, by the Austrian Josef Friedlander in 1883?

It stood at the north entrance of the Rotunde in the Prater and ran tools and lamps.

Which Scottish academic used a wind machine to light his Marykirk holiday home in 1887?

Months later the American Charles F. Brush built the first automatically operated wind turbine.

Which American inventor built the first automatically operated wind turbine, in 1887-88?

He got his blueprints peer-reviewed by local professors first; he was already famous for arc lights and dynamos in Cleveland.

In which US state was the first megawatt-class wind turbine connected to a utility grid, in autumn 1941?

By 1900 Denmark alone already had about 2,500 windpumps and mills producing some 30 megawatts of mechanical power.

Roughly what share of the world's electricity came from wind power in 2021?

That was up from 3.5% in 2015, with China and the United States adding most of the 100 GW installed that year.

Per a medieval account, which Rashidun caliph discussed windmill technology with a Persian builder?

The story was only written down in the 10th century, so its authenticity is questioned.

Which traveller brought horizontal windmills to 13th-century China after visiting Turkestan in 1219?

They were used for irrigation under the Jurchen Jin dynasty in the north.

What is the simple triangular cloth wound round a spar, common on Mediterranean windmills, called?

In colder climates the cloth of common sails was replaced by wooden slats that were easier to handle when frozen.

What did a drainage windmill typically drive to lift water?

Sawmills instead used a crankshaft to give the saws a reciprocating motion.

Which German engineer applied aircraft aerodynamics to windmill sails in the 20th century?

Several Dutch millwrights did the same; in France, Berton had earlier devised slatted sails the miller could open while the mill turned.

Fowler's Mill at Battersea and Hooper's Mill at Margate were rare British examples of what?

Built in the 18th and 19th centuries, they seem to have been independent inventions rather than descendants of the Persian design.

How many windmills did Cape Town have by 1863?

They stretched from Paarden Eiland to Mowbray; the Oude Molen's name survives on a technical school in Pinelands.

What was the main use of the earliest European windmills of the 12th century?

Windmills later powered paper mills, threshing, oil-seed crushing, wool and paint making and stone-working.

What did the Industrial Revolution mainly replace wind and water mills with?

Windmills nonetheless kept being built in large numbers until late in the 19th century.

Which La Mancha town is famous for the row of windmills beside its castle, linked to Cervantes' knight?

The region is known for dry plains and vineyards as well as its mills.

In Dutch windmill signalling, what does a slight tilt with the top sail at 1 o'clock mean?

A tilt to the 11-2-5-8 position signals mourning or warning, and was used to alert villages during Nazi searches in World War II.

What is the advantage of a windmill having an even number of sails?

Multi-sailed mills with five, six or eight sails were popular around Lincolnshire and Yorkshire.

Which Frenchman invented slatted sails that a miller could open while the mill kept turning?

Before such systems, a mill had to be stopped every time the cloth on the sails needed adjusting.

What is the structure often built around a post mill's trestle to shelter it and add storage called?

The trestle was a later wooden support for the great upright post on which the whole mill body turns.

In a grist mill, the great spur wheel drives which small gears on the millstone shafts?

Post mills sometimes skip the spur gear and use a head or tail wheel to drive them directly.

What mechanism does a wind-powered sawmill use to give the saws a back-and-forth motion?

Windmills also powered paper mills, threshing, and the processing of oil seeds, wool, paints and stone products.

The early Persian windmills had how many sails, covered in reed matting or cloth?

These vertical-axle mills ground grain or drew water and spread from the Middle East to Europe, China and India.