This is a drawn or ductile tungsten filament lamp, introduced in 1911. Notice the single, very fine metallic filament that is very long (about one or two feet in total length) and threaded or strung between two levels of several supports with hooks attached radially around the upper and lower portions of the button rod. This lamp was developed by the famed Schenectady General Electric scientist Dr. William D. Coolidge (1873 to 1975). [See A50]
Because tungsten in nature is such a brittle, delicate material that broke easily, it was believed by many scientists that tungsten could never be made ductile (or, in other words, plastic or malleable) and strong at room temperature [see A27]
. But the industrious Dr. Coolidge thought otherwise and actually spent a good number of years (from 1905 to 1910) working hard and diligently to accomplish the seemingly impossible. Throughout those five years, he performed a large number of experiments with tungsten by combining them with other materials and then selectively hammering, rolling, drawing and heat-treating the combined metals at various temperatures before allowing them to cool down to room temperature and then test them to determine if any of them would retain their hardness. His persistence ultimately paid off. In the end, he found that the repetitive heating and hot swaging of tungsten and then drawing it out through a die would allow it to retain its malleability after it had cooled. He had created a hard but ductile filament that could be shaped in any form at any desired length. Another milestone in the history of lighting was finally achieved. Lamps with these ductile filaments were very bright, lasted longer than any other previous lamps, and could withstand rough handling while mounted in any position. Thus Dr. Coolidge, born before Edison’s first successful lamp, had set into motion the last chain of developments that lead to today’s modern, economical and popular incandescent household light bulb. He lived to see the widespread use of incandescent lighting before he died at the age of 101 in 1975.
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