Today, we read a 400-year-old book on dams. 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.
Historian Garcia-Diego tells
about a remarkable book in the Madrid Library. It's
called the Turriano Codex, although Juanelo
Turriano -- who's name is on it -- wasn't the real
author. Whoever the author was, it's a magnificent
treatise on hydraulics, written in the 1560s. Book
IX of the Codex describes weirs, or river dams, and
it's a surprise.
But first let's locate the year 1560. In Spain,
Miguel de Cervantes -- the man who wrote Don
Quixote -- was a teenager. In England, Queen
Elizabeth had just been made queen. And in Italy,
Leonardo Da Vinci had died 40 years earlier. The
period we call the Renaissance was a century old.
The book and its illustrations are remarkably
detailed, and it displays an astonishing command of
civil engineering. In fact, the next large treatise
that really extended the subject was written by the
U.S. Bureau of Reclamation in 1938. And there the
kinship with the Turriano Codex is clear.
Book IX of the Codex shows scores of ways to
accumulate water, to divert it to other locations,
and to control flooding. Here are several kinds of
structural wooden frameworks for shaping both stone
and earthen weirs. There's a quick-and-dirty forest
weir made of local vegetation -- meant to handle
only one flood. We see masonry gravity weirs --
single-arch, double-arch, and joined-arch weirs.
Every kind of dam or weir imaginable.
This is not a Da Vinci sketchbook -- it doesn't
represent the author's flights of fancy. What we
see isn't invention, but a report on technologies
that were solidly in place. Da Vinci made
analytical sketches to show how he thought
whirlpools worked. This author reports what
whirlpools and eddies are known to do to dams and
how to combat that damage. A serious practical
engineer is relating the accumulated ingenuity of
his age. He shows us a kind of technocratic
innocence when he furrows his brow and tells us:
Weirs must need be built in all sincerity of
mind; nor should those who have the charge of
building them be burdened with a concern for gain,
lest they [do not] do what they should; for such
works demand great lavishness in materials ...
I suppose we all might be warned to work
with a "sincerity of mind." Yet there's a dreamlike
quality in his advice that we utterly abandon any
"concern for gain" when we do it. But those views
aside, it's a delicious surprise to learn how
complete the technologies of water management had
become by the time Queen Elizabeth was taking the
throne of England.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
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