Today, we think about guns, catapults, and human
ingenuity. 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.
No engine of our ingenuity
is more basic than the lever. It takes a hundred
different forms. One's the catapult -- a lever with
two unequal arms. At the end of the short arm is
either a rope or a large counterweight. At the end
of the long arm is a sling. To hurl a projectile,
you either pull the rope or release the
counterweight.
Catapults grew out of a labor-saving gadget -- the
counterbalanced bucket. A bucket on the long arm
was partly balanced by a weight on the short arm.
You gently forced the bucket down. Then you only
had to lift part of the weight of water.
A story survives from 400 BC. The counterbalanced
bucket was common by then. Yet one elderly Chinese
refused to use it. As he hauled a pail back and
forth, watering his garden, he complained about the
counterbalanced bucket. It was a cunning device, he
said, and people who use cunning devices have
cunning in their hearts. Maybe he had a point. The
Chinese soon made this work-saver into a savage war
machine.
Dating the catapult is hard to do. Chinese writings
use the word phao to describe anything
explosive -- a rock leaving a sling, or a gun or
firecracker. It's hard to be sure just what
phao means when we see it. We know
Chinese catapults were common by the 2nd century
AD. But they could've been around long before --
even while that old man watered his garden 600
years before.
The catapult stayed in China until the 1200s. The
Romans built a great armory of siege engines, but
they never used catapults! Every Roman throwing
machine was based on the bow and arrow. All their
artillery looked like slingshots and crossbows.
Meanwhile the Chinese threw stones as heavy as a
man. They threw them 300 feet. They flung fire,
arrows, and finally explosives at their enemies.
Chinese ships, armed with catapults, set out to
invade Japan in the 13th century. When a storm
stopped them, the Japanese called it a
kamikaze -- a divine wind.
By then, Arabs had the catapult. We probably got it
from them during the Crusades, but we only used it
for a little while. We soon gave it up for another
Chinese invention. In the 1300s, we took up
firearms. It was then -- just then -- that a
Chinese poet wrote this about the catapult:
The crags of the mountains, rounded by craft,
Are made to fly forth from the catch of a
machine;
Through wind and clouds they ride upon their
way,
Like shooting stars they thunder through space --
So this chapter in human ingenuity ends with a
strange image: a poet celebrating the genius of the
catapult in the very moment it gives way to a far
more terrible engine of war -- the gun.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
For the simplicity's sake, I've used the familiar
word catapult. Historians prefer to use
the French word trebuchet. The correct
term for the counterbalanced lifting device is
swape. The swape lets you divide the
force of lifting in two. Typically, to lift 80 pounds
of water, you would push the bucket down into the
water with a 40 pound force. Then it would take a 40
pound force in the other direction to lift the filled
bucket.
My source on this is the great scholar of Chinese
technology, J.H. Needham, who is also author of a
five-volume series on Chinese technology:
Needham, J.H., China's Trebuchets, Manned and
Counter Weighted. Humana Civilitas: Sources
and Studies Relating to the Middle Ages and the
Renaissance, Vol. I, On Pre-Modern
Technology and Science (B.S. Hall, D.C. West,
eds.). Malibu: Undena Publications, 1976.
I am grateful to Pat Bozeman, Head, Special
Collections, UH Library, for drawing my attention
to this uncatalogued source and making it available
to me. For more on the trebuchet and for links to
trebuchet websites, see Episode 593.
This medieval trebuchet, and other historical
images, may be found on an excellent trebuchet
website at: http://www.iinet.net.au/%7Ermine/gctrebs.html
The Engines of Our Ingenuity is
Copyright © 1988-1997 by John H.
Lienhard.
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