Today, we find a 2000-year-old computer on the ocean
floor. 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.
Just before Easter in 1900,
six Greek sponge divers and their crew were blown off
course in the Mediterranean between the islands of
Kythera and Crete. They dropped anchor by the tiny
island of Antikythera, just southeast of Kythera.
So they decided to dive into those unfamiliar waters
to see if they could find sponges. What they did find
was the badly decomposed hulk of a trading ship
that'd sunk around 80 BC -- just before Cleopatra,
just before Imperial Rome.
This was the first ancient wreck ever found. So the
Greek government sent the sponge divers back on a
navy ship. They dove 140 feet down into the wreck.
This was before scuba apparatus and breathing tanks!
They dove for a year, bringing up statues, amphoras,
and other trade goods. By the time they were done,
one diver had died and two were permanently crippled.
As newspaper stories about the find turned into
yesterday's news, scholars began looking closely at
one item -- a badly corroded set of brass gears,
cased in a wooden frame. But, in 1900, we didn't know
how to preserve ancient wood when we took it out of
the sea. The frame soon collapsed and broke apart.
They figured the gadget had to've been some kind of
navigational astrolabe, and the fragments lay there
in the museum. In 1973, Yale historian Derek de Solla
Price finally published a monumental seventy-page
study of the item. When he did, our whole view of
ancient Mediterranean technology had to change.
From what we can read of the inscriptions on the gears
we see this was a small planetarium, designed to calculate
and display the position of the sun and moon. Its complex
gear train was, in fact, a sophisticated analog computer.
To
learn all that, de Solla Price used every tool of the
metallurgist, radiologist, and engineering
kinematician. The differential gear train in this old
computer reminds me of the classic Model-T Ford
transmission.
The gear teeth themselves are triangular. That's not
very good gear design. Historians know that gearing
was first invented in Hellenistic North Africa only
about 200 years before. But they'd long assumed that
the Greek knowledge of gears was primarily
theoretical. Well, far from it! We'd been fooled
again because so few original artifacts survive. Old
brass gears have long since corroded or been melted
down and reused.
But the heroic factory gears of WPA art and Charlie
Chaplin's Modern Times weren't so modern
as they once seemed to be. Now the great marvel of
the late 20th century, the computer itself, turns out
only to be a new wine in -- a very old skin.
I'm John Lienhard at the University of Houston, where
we're interested in the way inventive minds work.
(Theme music)
