Abstract
MESSRS. Philips Lamps, Ltd., are introducing a new lamp which has an efficiency of about eight times that of a gas-filled lamp taking the same power. A description of the lamp is given in the Electrical Times for July 14. In the new lamp an electric discharge passes through a rare gas ‘filling’ with a small quantity of metallic sodium. There is an oxide cathode with one or two anodes. The bulb of the lamp is in the shape of a cylinder, which has to be heated up to a certain temperature sufficient to vaporise the sodium. The lamp is enclosed in a second cylinder, which accelerates the heating and keeps the temperature constant. The discharge and consequently the emission of light depend mainly on the sodium vapour. The colour of the light is yellow and practically monochromatic. This colour is favourable to good visibility and therefore the lamp is very suitable for street lighting. A photograph taken at night is shown of a long length of road in Holland illuminated by the new gaseous lamps. It has been noticed that drivers of fast cars when entering the newly lighted part of the road switched off their headlights unasked. Hence there is no ‘dazzle’ the elimination of which is one of the greatest problems of night driving. The candle-power of the lamps is 500-600 for the smallest size made, which take 100 watts. These lamps will be useful where colour is of minor importance. For domestic use a whiter light is more desirable.
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A High-Efficiency Gaseous Lamp. Nature 130, 124 (1932). https://doi.org/10.1038/130124a0
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DOI: https://doi.org/10.1038/130124a0