LAMPS LIT BY DARKNESS

Sun (Auckland), Volume II, Issue 560, 12 January 1929, Page 14

LAMPS LIT BY DARKNESS

LONDON’S LATEST WONDER For nine months the street lamps in Sheen Common Drive, Barnes, London, have been lighted by the agency of darkness and put out bv the action of daylight. Local residents have been unaware of the wonder at work in their thoroughfare. On a recent evening I watched the miracle happening, says a London newspaper man. As darkness fell the lamps, one by one, lighted up simply because a selenium cell attached to them had been influenced by the fading light. The apparatus is technically known as a light-sentitive selenium bridge. This is an apparatus which when connected across an electrical circuit lowers its electrical resistance if subjected to light—artificial or daylight. In the case of the street lamps in Barnes the mechanism switches the lamps on and off according to whether the selenium bridge is influenced by light or darkness. “The bridges affixed to the lamps in Sheen Common Drive,” said Mr. C. S. Davidson, chief engineer to the Barnes L’rban District Council, “have not failed during the nine months we have been using them. We have kept the matter secret at the request of Radiovisor Patent. Ltd., which supplied them. The selenium bridges are affected equally by fog as by dark- j ness.’’