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No. 1268:

Today, let us find our light. 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.

Sir Humphry Davy gave a famous series of lectures on natural philosophy at the Royal Institution of London starting just after 1800. Davy was enormously influential, and he returned again and again to the theme of light. Light and seeing were scientific fixations in the first half of the 19th century. That age produced dioramas, magic lanterns, photography, the first electric lighting (long before Edison), and public gas lighting.

Michael Faraday followed Davy in those lectures, and, in the early 1820s, a young member of the Royal Engineers, watched him do a demonstration. When Faraday turned an oxygen-hydrogen flame on a lump of quicklime, the heated lump emitted a brilliant light.

Drummond saw a new use for that fluky behavior. Setting distant markers for surveyors could radically improve the accuracy of geographic surveys. In 1825, Drummond set a limelight marker on a mountaintop near Belfast. It was so bright it could be seen in Donegal county, sixty-six miles away.

By now Drummond's limelight has become our metaphor for the glow of public approbation -- for being seen. That metaphor took shape in 1837, when limelight systems became sufficiently streamlined that they could be moved into the theater.

Just before Davy's first lectures, the English had begun obtaining domestic gas from coal and leaving behind clean-burning coke. By 1837, all major theaters were being lit by coal gas. After thousands of years with little change, gas lighting was now flooding stages with light -- far cheaper than the old candelabras and lanterns. And that created a craving for still more light.

Limelight finished the transformation of the theater. It cast the light of high noon on stages. Lenses and filters gave it the warmth that it lacked. It lasted until the new electric lighting systems arrived in the late 1800s.

But limelight found other uses as well. The military used it to illuminate enemies at night. During the siege of Charleston, the Union Navy focused limelight on Fort Sumter while they pounded it into rubble. Ships found one another by night. During the 1870s and '80s, workmen under the East River dug the caissons for the Brooklyn Bridge by limelight.

By 1952, when Charlie Chaplin made the movie Limelight, the word itself lingered only as a metaphor. "Find your light," an old actor tells the narrator in the play, Fantastiks. That means seek the center of the light that'll show you to the world. It means, "Find that same limelight beam which first cut through the night -- all the way from Belfast to Donegal."

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

(Theme music)

Penzel, F., Theatre Lighting Before Electricity. Middletown, CT: Wesleyan University Press, 1978.

Rees, T., Theatre Lighting in the Age of Gas. London: The Society for Theatre Research, 1978.

Beal, D., The Limelight. American Heritage of Invention and Technology, Fall, 1997, pp. 38-41.

For more on arc lights and early electric lighting systems, see Episode 11.


Picture of an unspecified type of stage lighting (probably arc lighting) ca. 1904
From Electricity in Everyday Life, 1904, provided by the Linda Hall Library