Today, we ring the Liberty Bell. 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.
Some technologies are so
evocative! Bells, for instance: The ghostly
Shropshire Lad hears the bells that once called his
love to church, called her to wed him -- then
called her to his funeral. Finally he screams, "Oh
noisy bells, be dumb! I hear you." Edgar Allan Poe
celebrates the "tintinnabulation that so musically
wells from the bells bells bells" -- from sleigh
bells, alarm bells, wedding bells. Bells signal the
turnings and changes of our lives -- from the first
hour of school to hailing a new government.
The Liberty Bell is a microcosm of political and
technological history. It was also a kind of
laboratory for both politics and technology. The
technology of bell-making pushes foundrymen to
their limits. Bells took their familiar modern form
in the 13th century -- with a flattish top, concave
sides, and a somewhat thickened lip; but they've
always been hard to make. For one thing, the shape
is hard to cast. Bronze of 77 percent copper and 23
percent tin seems to be the best metal to use. That
mix strikes a delicate compromise between tone
quality and brittleness. The bronze Liberty Bell is
3 feet high, and it weighs a ton.
It was actually made long before the American
Revolution. It was ordered from an English bell
foundry in 1752 to celebrate Pennsylvania's 50th
anniversary. Yet its inscription from Leviticus
foresaw its role: it says,
Proclaim liberty throughout all the land unto all
the inhabitants thereof.
The English bell cracked even before it
was put in its tower. So a Philadelphia foundry
undertook to recast it. They tried make it less
brittle by using extra copper, but that bell had a
dull sound. So they put the tin back in and cast the
third and final bell. It first rang in 1757 at a
meeting in which the legislature sent Ben Franklin to
England with a list of grievances. From then on it
rang the great events of the Revolution -- it was
muffled to toll a death knell for English taxation --
it called rebel meetings -- it celebrated victories.
But it didn't ring on the 4th of July. The 4th was
merely an intended date. The actual proclamation
was delayed until July 8th. Then the bell did
indeed ring out. And it went on signaling the great
events of our land until 1835. Finally, as it
tolled the death of Chief Justice John Marshall, it
cracked.
But it was now 78 years old. It was a creature of
trial and error. It started out English and saw us
through to an established America. It followed an
odyssey of political change. In the end it became
the perfect national symbol.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
