Today, a look at black American inventors before the Civil War. 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.

The slave population in the American colonies reached a maximum of a quarter-million in 1754. But it dropped off as we approached, and fought, the Revolutionary war. For a while, people thought slavery might die out entirely.

But technology intervened. Eli Whitney patented the cotton gin in 1793. Suddenly we could turn a profit on this terribly labor-intensive crop. From then until the Civil War the slave population increased to the astonishing level of 4,000,000.

The grand irony of all this is that the person who provided Whitney with the key idea for his gin was himself a slave, known to us only by the name Sam. Sam's father had solved the critical problem of removing seeds from cotton by developing a kind of comb to do the job. Whitney's cotton gin simply mechanized this comb.

The technologies of the Old South, of course, flowed from the people who were doing the jobs that had to be done. The story of Sam was repeated in different ways over and over. Slaves invented technology, but they couldn't patent it. In 1858, the United States Attorney General -- a man named Black -- ruled that, since slaves were property, their ideas were also the property of their masters. They had no rights to patents on their own.

So our knowledge of slave contributions comes to us in anecdotal forms. The paper trail is very thin. For example, various claims are made about the contributions of a slave named Jo Anderson who worked with Cyrus McCormick on the development of his reaper. It's hard to find out where Anderson ended and McCormick began. However, author Robert Hayden finds a better-documented case in Southern newspaper reports during the Civil War. They tell about one of Jefferson Davis's slaves who invented a new screw propeller for steam-driven ships. He couldn't patent it, of course; but it served the South during the war that was fought to keep him a slave.

The first patent to a black freeman was given in 1834 to Henry Blair for his new seed-planter. But records of patents, even to freed blacks, are rare before the Civil War. For one thing, black inventors usually put their patents in the name of a white lawyer. That improved chances for acceptance of their invention.

The lesson in this is that disenfranchised minorities look unproductive because they have no franchise. Historians of technology are just beginning to see that the slave inventors we know about are only the tip of a very large iceberg.

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

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Hayden, R. C., Black American Inventors. Reading, Mass.: Addison-Wesley Pub. Co., 1972.

James, P.P., Enslaved Inventors, Hidden Contributors. The Real McCoy: African-American Invention and Innovation. 1619-1930, Washington, DC: Smithsonian Institution Press, 1989, Chapter Three.

For more on this business, see Episode 1076.

This was a very early episode in this series. As it turns out, the story of Whitney getting his cotton gin idea from Sam is probably apocryphal. For a more recent account of the develop of the cotton gin, see Episode 2494.