ROBERTSON CARBON FILAMENT BULB, 1920's

Robertson Carbon Filament bulb 80 Volt 8 Candle Power
Within a very few years, the Robertson Lamp had proved itself by far the most successful in the UK marketplace. In spite of this lamp being the most expensive on the market, the factory was producing and selling 4 million lamps per year by 1904. The statistic is significant because at the beginning of 1904 the thermionic valve had not been invented, many of the materials, technologies and processes that would be needed for valve making were already in place by virtue of the effort expended on establishing manufacturing of the electric lamp.

A0695