Today, we wonder about theaters, computers, and the deus ex machina. 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.

Two Greek words swirl about the things we make. One is techni. Techni is the art and skill of making anything from an engine to an etching. It's a wonderful word. It acknowledges that engineers and artists are yoked in the same enterprise.

The other word is mechane, from which we get machine. It's a less noble word. It tells of devices -- of gears, pulleys and such. Mechane tells of manipulation, while techni tells of art.

The word mechane comes down to us in the Latin expression deus ex machina, or "god out of the machine." That's what we call any cheap theatrical device. An unexpected god steps out of a clever stage machine to save the hero at the last second. A fairy godmother appears in a puff of smoke to pay the mortgage.

But good stagecraft is far more than cheap stunts. Every set designer who's ever done Faust or Samson has wondered how to carry Faust down into Hell or how to bring the temple down on Samson. Think about the staging demands of Wagnerian opera.

Now I thumb through my latest issue of Mechanical Engineering. I scan articles on heat pipes, turbofans, fibre optics, and, right along with all that, computer-aided theater-set design.

The New York Metropolitan Opera recently staged Bela Bartok's opera Bluebeard's Castle. The set designers changed Bluebeard's ship into a spaceship. Worse yet, they wanted us to approach Earth from space. They did that by heaving a huge wall of stone back to reveal Earth girdled by swirling clouds. The wall had to stay rigid. If it fluttered, so would the illusion. The task was formidable. In the end, it was solved by a group of engineers armed with the latest tools of computer design.

Of course, those same engineers have also tackled Wagner. The Flying Dutchman's ship must descend from the dark sky to set its cursed captain on the stage. Then it must rise back into the mist. Easy enough if you're willing to paint a ship on a backdrop, lower it, and let the captain walk out through a door in the side! But modern opera-goers demand better, and they get it.

Stages are large, and so are the sets that fill them. Designing a set goes far beyond specifying what it'll look like. Sets pose terrible structural problems. The Dutchman's ship may not satisfy physics, but the machinery of storytelling must.

Theater sets are illusions. Computers also deal in illusion. Yet they are techni. They are the stuff of our dreams. Computers manipulate what we first dream. The theater hones our vision of reality by mirroring our dreams. Neither welcomes the lesser god of mechane, sprung from a secret box.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Paulsen, W.C., Engineering Theatrical Magic. Mechanical Engineering, Vol. 112, No. 8, August 1990, pp. 28-30 and Cover.

Paulsen is vice president of Algor Interactive Systems, Inc., in Pittsburgh, Pennsylvania -- the company who did the designs I allude to above. They use the techniques of Finite Element Analysis (FEA) to do the structural design required in a large variety of stage designs.

The expression deus ex machina comes from the older Greek expression o apo mechanes theos, which also means "god out of the machine."