ABSTRACT
Up to the end of the nineteenth century artificial light, or light derived from sources other than daylight, was associated with heat, for whilst Sir Humphry Davy had demonstrated the ‘arc lamp’ as early as 1810, its use as a practical light source had been restricted to providing large amounts of light, as for example in lighthouses. It was not until Swan and Edison developed the carbon filament lamp, or the light bulb as it became known (using a tungsten filament), towards the end of the century that light from electricity became a practical reality.
