Today, necessity, invention, and the Siege of
Paris. 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.
So is necessity the
mother of invention? The four-month Prussian siege
of Paris in 1870 offers some clues. Telegraph lines
had been cut, and Paris couldn't communicate with
the rest of the world. Necessity demanded a
solution.
Parisians wished they could fly over the enemy's
lines. In fact, two usable forms of flight did
exist: carrier pigeons and balloons. Balloons could
get out, but where they went was uncontrollable and
only vaguely predictable. And there was no way to
guide a balloon into Paris from outside. Carrier
pigeons couldn't be sent anywhere; they could only
find their way back to Paris.
The obvious trick was to fly both messages and
crated pigeons out of Paris in balloons by night,
and to send microfilmed messages back by carrier
pigeon. Several pigeons had to be sent with
duplicate messages because enemy soldiers shot as
many as they could.
In 1871, James Glaisher added that story to the
second edition of his book about ballooning,
Travels in the Air. The situation in Paris
fairly screamed for creative invention, but
Glaisher is quite explicit in saying there was no
time for that. He says,
... there was no time to originate fresh
constructions or introduce new principles. The old
invention as it stood was to be stimulated into
success, if success were to be had.
So Parisians went to work. They set out to build
balloons the same way they'd always built sporting
balloons. The Post Office commandeered two train
stations for factories, while trains stood idle.
Precious silk was the fabric of choice for
balloons, but for mass production they had to use
calico. To make the cloth airtight they painted it
with linseed oil and lead oxide.
The Northern Station had the new sewing machines. Workers at
the Orleans station had to stitch the gasbags
together by hand. Landlocked sailors went to work
painting, varnishing, twisting cables, and then
flying the finished balloons. They thrived on the
work. It was like being back amongst the sails on
their ships.
The balloons were filled with coal gas. That was a
mix of light gases -- not as light as hydrogen,
which was hard to come by, but lighter than hot
air. And a coal-gas-filled balloon didn't need a
reheating flame that would attract enemy fire.
From September through January, sixty-two one-way
flights left Paris. It was old technology, serving
grave necessity -- a heroic effort. But it left
behind all kinds of new questions about flight.
Glaisher finishes by looking at the claim that
progress and invention spring from the exigencies
of war. He concludes that it's very far from being
universally true.
Necessity had been a mother all right, but not of
invention. Her real children were the focus,
determination, and action that held Prussia at bay
until an armistice could be signed.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
Glaisher, J, Flammarion, C., de Fonvielle, W., and
Tissandier, G., Travels in the Air. 2nd and
revised ed. London: Richard Bentley & Son, 1871.
See especially the Preface to the Second edition.
For more on balloons in the siege of Paris, see
Episode 1132.
I am grateful to Margaret Culbertson, UH Art and
Architecture Library, for bringing the Glaisher
book to my attention and for making it available to
me.
Early photo of the first balloon leaving Paris
during the siege
Frontispiece of the Glaisher book: Mirage and
Luminous Aureola
The Engines of Our Ingenuity is
Copyright © 1988-1999 by John H.
Lienhard.
