Today, we meet the King, his mistress, and a smart young astronomer. 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.

King Charles II took yet another mistress in 1670. She was a dark-haired beauty from Brittany in France. She bore him a son two years later, and he made her the Duchess of Portsmouth. The Duchess was the King's clear favorite. Some wondered if she might not be a French spy in the English court.

By now a scientific question was gathering importance. This was the age of navigation. European ships were ranging the oceans. It was easy enough for navigators to fix their latitude. But no one knew how to find their ship's longitude. That was the uncertainty that almost killed Columbus, 180 years earlier.

The King had recently created the Royal Society to advance science. Now the Society urged him to build an observatory. We needed better astronomical data to solve the longitude problem.

The proposal was foundering in red tape. Then the Duchess produced a friend from Brittany. He was an amateur astronomer named St Pierre. Once in the English Court, he claimed he could calculate longitudes.

In December, 1674, the King set up a Royal Commission to study St Pierre's method. It included Christopher Wren and Robert Hooke. Those were heavy hitters. But, for astronomical advice, they turned to a young man named John Flamsteed.

Flamsteed saw that St Pierre's method was inherently inaccurate. Worse yet, he'd taken it from two other astronomers, long dead. And when Flamsteed questioned St Pierre, he found the fellow didn't even understand the method he was proposing.

Flamsteed reported to the King that we'd have to get longitudes by another method entirely. Then we'd only do it when we had far better data on locations of stars and planets.

Flamsteed's answer to St Pierre made it crystal clear that England urgently needed the observatory. King Charles reacted. That very day he signed the warrant to build the Greenwich Observatory. He set up the world benchmarks for longitude and time.

So the Duchess's friend St Pierre went back to France. We don't hear from him again. Yet he and the King's mistress had precipitated one of the important scientific projects of all time. Ten years later, the King elevated another mistress to the aristocracy. He made her -- and not the Duchess -- Countess of Greenwich.

So the King and his court swirled about and played their roles. But in the midst of it all was quiet John Flamsteed. And it was he who really redirected history.

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

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Howse, D., Greenwich Time and the Discovery of Longitude. New York: Oxford University Press, 1980, Chapter 2.