Today, a lesson in shameless grandeur and simplicity. 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.

We call the confluence of the Harlem and the East Rivers in New York City Hell's Gate. Dramatic, I suppose, but why not! A bridge opened over Hell's Gate in 1917. It's an arch of iron girders. The arch thickens at each end. It thins toward the center. You get a feeling of buoyancy looking at it.

Othmar Ammann, who designed the bridge, caught Hell for it. This, says writer Christopher Bonanos, was an age of ornament, gravity, solidity, and dignity. Ammann's design was imperfect in some ways. But its simplicity, lightness, and freedom signaled a new era in design.

Ammann had finished an engineering degree in Switzerland in 1902 and had come here soon after. Now -- in 1930 -- he was hard at work on two really grand bridges that're sure to carry his name far into the 21st century.

One was the Bayonne Bridge -- an expanded version of his Hell's Gate triumph. It's a huge graceful arch of open structural steel. The other was the longest suspension bridge up to that time. It's the George Washington Bridge with its 3500-foot span.

The George Washington Bridge also has open structural steel towers. At first they were to've been faced with stone, but the Depression required cost cutbacks. Had Ammann meant all along for that great steel span to stand naked at the north portal of New York City? He never would say.

Whatever Ammann's intentions, the outspoken modern architect Le Corbusier called it the most beautiful bridge in the world. Meanwhile, Ammann kept tying New York to land. He built the Bronx-Whitestone Bridge. He built the Throgs Neck Bridge.

When Ammann died at 86 he'd just finished his last masterpiece. For the second time he'd given us the world's longest suspension span. The Verrazano Narrows Bridge is a plain study in grace, with a 4300-foot central span.

He created a radical new deck design for the Verrazano Bridge to keep it from galloping in the wind. The deck thins toward its edges to guide wind around it. Ammann's work was meticulous. The towers are an inch and a half wider at the top to keep gravity's force dead-vertical -- despite Earth's curvature.

So this remarkable 19th-century engineer left his stamp on bridge-building down through the 20th century. He helped shape a new attitude toward design. Ammann was born ten years before the Eiffel tower was built. And he showed us the steel at the heart of design. Writer Bonanos says that he expressed structure without shame. It is that shameless joy in naked function that touches us. It is the simple grandeur of open steel against the sky.

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

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Bonanos, C., The Father of Modern Bridges. American Heritage of Invention and Technology, Summer 1992, pp. 8-20.