In 1825, Thomas Drummond invented the Drummond light. This consisted of a cylinder of calcium oxide or lime, heated in a hot hydrogen-oxygen flame and put in front of a reflector or behind a lens. The result was a glaring white light visible from a great distance.

Drummond, a lieutenant in the Royal Engineers, was working with the Ordnance Survey in Ireland and used his invention to measure distances accurately. His light was later used in lighthouses and also in the theatre as a spotlight to draw attention to the principal artiste.