Today, we meet a reluctant explorer. 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.

In 1842, John Fremont, then a young army lieutenant, prepared an expedition out of St. Louis to map the Pacific Northwest. There he took on a German mapmaker named Charles Preuss. Preuss was 39 years old, red-faced, and by the sound of his own diaries, ill-humored as well. They were a badly matched pair. Science writer John Noble Wilford calls Fremont the archetypical Western hero-explorer -- and Preuss the grumbling tenderfoot.

Fremont also added a young guide named Kit Carson to his troop. Then he set off on the first of two journeys that would establish Fremont's and Carson's fame and tell America the shape and reach of its huge forbidding West.

When they came to Wyoming's Wind River Mountains, Fremont dragged his party up the highest peak to make a speech and plant an American flag. That piece of theater was duly recorded in two places. The Eastern newspapers thought it was just grand. In his diary, Preuss grumbled about Fremont's childishness and wished he could be back home with his wife.

Preuss' diary goes on: "... eternal prairie and grass ... I wish I were in Washington ..." he says. Or "I [haven't] formed a very high opinion of Fremont's astronomical manipulations ... I wish I had a drink." Preuss seemed to be as wrong for the job as one could be. But he played perfect counterpoint on Fremont's stage. If Fremont saw the poetry in the unfolding landscapes about him, Preuss saw precise longitudes and latitudes. Preuss's accuracy wasn't going to be jiggled by dreams.

In an odd way, Fremont seemed to understand their relationship better than Preuss did. By some trick of charisma, he dragged Preuss off on a second trip in 1843. This time Preuss gave Congress the definitive maps of the American West. And he did it on the eve of the great American westward expansion. His maps led Brigham Young to Great Salt Lake. They led my great grandfather to California before the gold rush, and thousands more just after.

The Preuss/Fremont collaboration continued through several more expeditions. Finally, in 1853, Preuss reached 50, and his constitution simply couldn't take it any more. He had to quit these adventures. Then it all went bad. Preuss committed suicide a year later. Fremont went on into high politics and was soon seen by the American public as a showman and a fake.

Together, Fremont's dreams and Preuss's technical ability gave us the first real view of Western America. Apart, neither could survive. And so it is with technology. Neither our dreams nor our execution can stand by themselves. We need them both -- we go nowhere if we don't have them both.

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

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Wilford, J.N., The Mapmakers. New York: Vintage Books, 1982, Chapter 13.