Prologue
The common light bulb of today has been around since Thomas Edison introduced it in the year 1880. It has always been the desire to eliminate, or at least reduce, the bulb blackening that appears in all lamps, and which is one cause of light reduction with time. Two attempts to alter the nature of the darkening in carbon filament lamps will be mentioned briefly. With the advent of the gas-filled lamp in 1913 blackening was reduced somewhat and the location of the discolored area was changed due to the presence of convection currents. Then, a lamp that gives 100% lumen maintenance throughout life, the tungsten-iodine, is reviewed. In addition, biographical sketches of three individuals who were key contributors in the success of the regenerative cycle lamp are presented.