One night in 1837 a bright light beamed on a juggler in Covent Garden in London. It was the first use of a Limelight - an intense white beam produced by heating a piece of lime (Calcium Oxide) in a flame burning oxygen and hydrogen.
First discovered in the 1820’s by Goldsworthy Gurney, and demonstrated by Michael Faraday, the application of the light was brought to land surveying by Sir Thomas Drummond. By 1856 limelights were used at Fort Sumter at the beginning of the Civil War, and during the night construction of the Brooklyn Bridge. The first theatrical installation was put to use in London's Princesses Theater.
Operators would sit on bladders of oxygen and shift their weight to control the pressure. Not unlike a bagpipe of light? Not surprisingly, accidents were common. London’s Drury Lane Theater burnt to the ground after a bag burst.
Actors on stage, in the center of the beam were literally ‘in the limelight,’ however the turn of the phrase outside of the theater really caught on around the turn of the century.
Because the light was so intense, and because (reportedly) the light had a slight greenish hue, actors would get ready and rest in a room painted green. This was to allow the actors to adjust their eyes. It’s been said this is the origin of the term ‘green room.’ Although other sources say that ‘green’ is the area of grass where actors would wait to go on stage, the term is still used for the talent preparation room to this day in theater and television production.