Today, a strange parable of appearance and reality.
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.
Roller skates are odd
gadgets, if you think about it. Each skate is a
small four-wheeled platform. A single roller skate
isn't enough to provide a stable base. After all,
you can't really stand on a skate. When you move
forward, you fall from an unstable perch on one leg
to catch yourself on the other.
In that sense, roller skates are like bicycles. The
modern safety bicycle was finally perfected in 1885
after 50 years of experimentation. You're never
stable on a bike. You're constantly just starting
to fall and correcting your motion.
So the four-wheeled roller-skate platform is only
an illusion. Eliminate the illusion -- put the
wheels in a single row -- and you gain fluidity and
control. All you lose is the stability you never
had in the first place. Of course, when you do
that, you get the in-line roller blade -- something
you see everywhere today.
Now the surprise: The first roller-skate patent was
issued in 1819. The patent drawing shows three
wheels in a line. The roller blade came before the
four-wheeled platform skate!
Yet it was 1981 before Scott Olson founded
Rollerblade, Inc., in Minnetonka, Minnesota. Olson
wanted to keep up his ice hockey skills during the
summer. Since that beginning, roller blades have
gone through a dizzying series of experimental
designs. They're now made with from two to five
wheels and complex arrays of bearings and braking
Leo O'Connor writes about this design profusion in
Mechanical Engineering magazine.
Roller-bladers cruise at around ten miles an hour
-- a lot faster than the old roller skates. An
expert will reach 50 mph on a downhill run. Once
released from the idea of a platform, we've become
drunk on a new concept of motion. Yet there's an
odd historical continuity in the story of the
Eighteen years after the modern bicycle took its
form, Orville and Wilbur Wright took the concept of
instability to Kitty Hawk, North Carolina. There,
in the coastal dunes, they finally removed the
flawed concept of stability from the airplane. They
created an unstable airplane whose motion had to be
controlled in flight. Only then did they succeed
where everyone else had failed.
And I'm left puzzled. Why did it take a century?
It's a reminder of the way we hamstring invention
by assuming illusory constraints. Just think: we've
used no more than the illusion of stability to
protect generations of children -- as they ride
about with skinned knees, on their four-wheeled
I'm John Lienhard at the University of Houston,
where we're interested in the way inventive minds