Today, a parable about magical machines and ideas.
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.
You may've heard of Hero's
Turbine. Hero was an engineer in Alexandria during
the first century AD. His turbine was a hollow
metal ball with steam nozzles. You heated it up and
steam jets whirled it around.
Hero's turbine didn't produce power, but it showed
that gases like steam can make things move. His
book, Pneumatica, is filled with such
eerie machines. A temple door seems to open by
magic. Actually it's driven by the pressure of
This was 1900 years ago. Yet Hero offered a
completely modern theory of gases. Gases are made
of atoms, he said. Between the atoms is vacuum.
Hero didn't invent the atomic theory. Long before
him, the Greeks argued about matter. Was matter
made of atoms or was it earth, air, fire, and
water? Now Hero tied atoms to the magic of real
machines. He gave flesh and blood to atoms.
By the Renaissance, earth, air, fire, and water
held absolute sway. Then Leonardo da Vinci read
Hero. Leonardo loved all that machinery. Next, the
alchemists got their hands on Hero. They loved the
magic of his machines. They were no more interested
in his atomic theory than Leonardo was. One
What so intricate, and pleasing withal, as
[Hero's] works, on the air engine, the war engine,
the engine that moveth itself ...
The alchemists had no use at all for
atoms -- only for those lovely old Afro-Roman
machines. So they read and translated the old books.
As they did, Hero's theory found its way to people
who would accept atoms.
Galileo read Hero and became a powerful advocate of
the atomic theory. Torricelli read Hero and
explained atmospheric pressure. Boyle read Hero and
gave us the ideal gas law.
Meanwhile, the alchemists swam in a sea of earth,
air, fire, and water. But all that magic machinery
beguiled them. So they took the wolf into their
fold. Others began using atoms to describe what
they saw in nature. In 200 years we had a modern
atomic theory, full blown; and alchemy finished its
But even before that, we started building steam
engines. That wasn't because of Hero's steam
turbine. It was because Hero's magical engines
caught the fancy of scientists whose beliefs were
ripe to fall. Hero finally convinced us that flimsy
gases could exert the force we needed -- to propel
us into the 20th century.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
Boas, M., Hero's Pneumatica: A Study of its
Transmission and Influence. Philosophers and
Machines. New York: Science History
Publications, 1976, pp. 90-100.
The alchemical quotation is from, Burton, R.,
The Anatomy of Melancholy. New York:
Tudor Pub. Co., 1927. (the original was published
in Latin in 1621.)
For more on the transition from alchemy to modern
science, see Engines episodes 474, 511,
610, 613, 614,
For more on Hero, see Episode 1038.
The Engines of Our Ingenuity is
Copyright © 1988-1997 by John H.
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