4. First case study – the subdivision of the light - HM Treasury

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F05 Ch4 Subdivision of the light.doc 05/04/2006 19:34:00 Technological roulette – a multi-disciplinary study of the dynamics of innovation in electrical, electronic and communications engineering. 4. First case study – the subdivision of the light Lamps of this type took at least a minute to reach operating conditions and, under critical conditions, were provided with one or more carbon filament lamps which were coupled to the heating coil circuit and extinguished when the solenoid operated. The Nernst lamp was manufactured in ratings of 16 to 250 candles. It was positioned between the arc lamp and the ordinary incandescent lamp and could perform certain lighting tasks more effectively than either. Its efficiency advantage over carbon lamps led to a fairly wide take-up, both in Europe and the United States. When the Nernst lamp was first introduced and promoted, central-station operators were uneasy about the effect of its greater efficiency on their revenues. They feared that their customers would simply substitute Nernst lamps for carbon lamps completely and that the sale of energy would decline. In practice this did not happen because the Nernst lamp could not satisfactorily replace all carbon lamps, and, in those applications in which it could, users took advantage of its greater efficiency and economy to provide higher levels of illumination rather than to reduce lighting expenditure. By 1912, however, the ductile tungsten filament lamp gave further improvements in efficiency for general lighting purposes and the Nernst lamp was, in turn, superseded, although it was still in use as late as 1926 for specialist applications such as a powerful point light source for instrumentation. Fürst 1926 Nernst applied for German, British, and other patents on his invention in 1897, and patents on a number of improvements issued in 1899. He withdrew from active participation in the final development and commercialisation of his invention and sold the patents to Allgemeine Elektrizitäts Gesellschaft. AEG retained for itself sole selling rights for Germany and some other European countries, but disposed of the patents elsewhere. George Westinghouse obtained the rights for the United States and Canada and set up the Nernst Lamp Company to make the new lamp. This was the only major new incandescent lamp introduced in the United States between 1897 and 1912 that was not controlled by General Electric. Ganz & Company secured the rights for Austria, Hungary, and Italy. The Nernst Electric Light Company, Ltd., was formed in England to acquire the rights for Australia, Africa, Asia, South America, and Central America, whilst the rights for Britain itself were sold to GEC. The validity of the Nernst patents 77
F05 Ch4 Subdivision of the light.doc 05/04/2006 19:34:00 Technological roulette – a multi-disciplinary study of the dynamics of innovation in electrical, electronic and communications engineering. 4. First case study – the subdivision of the light was upheld in Germany but was not seriously challenged outside that territory. Bright 1949, p171 4.6 The arc lamp 4.6.1 Early developments In its simplest form, the electric arc consists of a pair of electrodes connected to an electric power supply. In operation, the tips of the electrodes are brought into contact, completing the circuit and causing a current to flow. The tips which are then separated slightly so that current continues to flow. This maintains the electrodes at white heat. In the form first developed by Davy, the arc was impracticable as a source of illumination. The electrodes were fabricated from wood charcoal and were rapidly consumed by combustion. They had to be repositioned by hand, which often could not be achieved with sufficient precision, with the consequence that the arc was extinguished after a short time. Furthermore, the voltaic pile was not a viable source of current when a durable supply was required. Towards the end of the 1830s, Daniell, Grove and Bunsen developed forms of primary cell and this attracted renewed attention to the possibilities of electric lighting. In 1841, Deleuil attempted to illuminate the Place de la Concorde in Paris by means of charcoal electrode arc lamps. Consumption of the carbons was inhibited by placing them in air-free glass bells, but the proposal was only moderately successful. In 1844, Foucault, who later used a pendulum to demonstrate the rotation of the Earth, effected a considerable improvement by constructing the electrodes from harder retort carbon, which was manufactured from coke, a by-product of the preparation of gas from coal. British patents for the purification of carbon were granted to Church in 1845 and to Greener and 78 Fürst1926 Fig. 4.14 Basic electric arc Furst 1926 Fig. 4.15 Dubosq’s sunrise effect (1849)
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4. First case study – the subdivision of the light - HM Treasury

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