The genesis of incandescent lamp manufacture

The Victorian engineers displayed considerable ingenuity in overcoming technical problems and successfully manufactured the first carbon filament incandescent lamps. Apart from Swan and Edison, many others shared in this achievement. The materials and scientific knowledge at that time were limited; this article reviews the key steps that were made in manufacture-particularly in producing homogeneous filaments-in an amazingly short space of time. Some ideas ´withered on the vine´, some survived and yet others have been recycled. The conversion of recorded candlepower into lumens is not straightforward and the performance of early lamps has often been overestimated. Calculations have been made using surviving filament data, coupled with modern information on carbon filaments and fibres, to obtain from first principles the luminous efficacy of these early lamps