Today, let's tilt at windmills. The University of
Houston's College of Engineering presents this
series about the machines that make our
civilization run, and the people whose ingenuity
created them.
Don Quixote dwelt in the
twilight of the age of chivalry in the fourteenth
or fifteenth century, but he was a creature of the
late sixteenth-century author Cervantes. Early in the story,
Quixote cries,
Look there, my friend Sancho Panza,
where thirty or more monstrous giants present
themselves,
all of whom I mean to engage
in battle and slay!
He points to an array of power-generating windmills
that dot the Spanish landscape. Windmills had
rapidly come into wide use in Europe beginning in
the late twelfth century. That was two hundred
years before Quixote and four hundred years before
Cervantes. For years we wondered whether Crusaders
brought windmills to Europe from the Holy Land or
vice versa. Today we're pretty sure they originated
in the Middle East. But a new form of windmill
suddenly appeared in Northern Europe right around
AD 1180.
European waterwheels were the primary energy source
when windmills arrived. Windmills were more
complex, and they were at the mercy of the
sometimes fickle winds. But they delivered more
power than waterwheels, and they ground grain where
there were no streams -- in the Spanish plains, for
example. Windmills provided the power to drain the
Dutch Lowlands below the level of any
streams.
By 1760 windmills had reached an astonishing level
of sophistication. Automatic regulators controlled
the speed of rotation; they adjusted the pitch of
the fan blades for maximum power at a given wind
speed, and they turned the fan so it always faced
directly into the wind. When windmills were used to
grind grain, controllers regulated the pressure of
the millstones on the grain.
But it was also in the 1760s that Watt began
developing a vastly improved steam engine. As the
eighteenth century closed, engineers stopped
pouring their energies into windmills, and they
turned to steam. James Watt was the Quixote who
really slew the windmill.
Of course windmills didn't go away. Today they're
still the power supply of choice for isolated use
away from commercial electricity. We use them to
fill cattle-watering troughs on the prairie, for
example. As railways opened the West, every
whistle-stop installed a windmill-supplied water tower to
refill steam-engine boilers.
Now we're seeing a new interest in wind power.
Latter-day engineers are concocting a dizzying set
of improvements to make windmills serve electric
power generation. The modern propeller-bladed
windmill is three or four times as efficient as an
advanced eighteenth-century mill, and far more
powerful.
But eighteenth-century windmills remain a forgotten
glory. Did you know that the variable-pitch
propellers used in those mills over two hundred
years ago are an invention that airplane designers
didn't rediscover until the 1930s?
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
George, B., Reaping the Wind. American Heritage of
Invention & Technology, Vol. 8, No. 3, Winter
1993, pp. 8-14.
Kealey, E., Harvesting the Air: Windmill
Pioneers in Twelfth-Century England. Berkeley:
University of California Press, 1987, Chapter 7.
Mayr, O., The Origins of Feedback Control.
Cambridge, MA: MIT Press, 1970.
Righter, R. W., A Few Words About This Picture.
American Heritage of Invention &
Technology, Vol. 7, No. 1, Spring/Summer 1991,
pp. 28-31.
White, L., Jr., Medieval Technology and Social
Change. New York: Oxford University Press,
1966, Chapter 3.
This episode is a considerably revised version of
Episode 29.
For more on windmills, and for additional reference
material, see Episodes 537, 552,
607, and 766.
From the October, 1896,
Scribner's Magazine
Artist's sketch of an actual windmill on the
Quixote's plains of La Mancha
The Engines of Our Ingenuity is
Copyright © 1988-1998 by John H.
Lienhard.
Previous
Episode | Search Episodes |
Index |
Home |
Next
Episode
