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William D. Coolidge

William Coolidge (far left)
Born October 23, 1873
Hudson, Massachusetts
Died February 3, 1975 (aged 101)
Schenectady, New York
Residence United States
Nationality American
Fields Electrical engineering
Alma mater University of Leipzig
Massachusetts Institute of Technology
Known for his contributions to the incandescent electric lighting and the X-rays art
Notable awards IEEE Edison Medal

William David Coolidge (October 23, 1873 – February 3, 1975)[1] was an American physicist, who made major contributions to X-ray machines. He was the director of the General Electric Research Laboratory and a vice-president of the corporation. He was also famous for the invention of "ductile tungsten", which is important for the incandescent light bulb.


Early years

Coolidge was born in Hudson, Massachusetts. He studied electrical engineering from 1891 until 1896 at the Massachusetts Institute of Technology (MIT). He went to Germany for further study and received his doctorate from the University of Leipzig. From 1899 to 1905 he was a research assistant to Arthur A. Noyes of the Chemistry Department at MIT.

Ductile tungsten

Coolidge went to work as a researcher at General Electric's new research laboratory in 1905, where he conducted experiments that led to the use of tungsten as filaments in light bulbs. He developed 'ductile tungsten', which could be more easily drawn into filaments, by purifying tungsten oxide. He applied for and received a patent (US#1,082,933) for this 'invention' in 1913. However, in 1928 a US court ruled [2][3] that his 1913 patent was not valid as an invention.

Improved X-ray tube

In 1913 he invented the Coolidge tube, an X-ray tube with an improved cathode for use in X-ray machines that allowed for more intense visualization of deep-seated anatomy and tumors. The Coolidge tube, which also utilized a tungsten filament, was a major development in the then-nascent medical specialty of radiology, and its basic design is still in use. He filed for patent in 1913 and finally it was granted as US Patent 1,203,495 in 1916.


Coolidge was awarded the American Institute of Electrical Engineers Edison Medal in 1927 For his contributions to the incandescent electric lighting and the X-rays art. He rejected this prestigious award in 1926 on the basis that his ductile tungsten patent (1913) was ruled by court as invalid. In 1975 he was elected to the National Inventors Hall of Fame, shortly before his death at age 101 in Schenectady, New York.



  1. ^ Suits, C. G.. "National Academy of Sciences Memorial Biography". National Academy of Sciences. Retrieved 2008-05-09.  
  2. ^ General Electric Co. v. De Forest Radio Co., 28 F.2d 641, 643 (3rd Cir. 1928)
  3. ^ Lakshman D. Guruswamy, Jeffrey A. McNeely, Protection of global biodiversity: converging strategies. Duke University Press, 1998, p.333.
  • M.F. Wolff, "William D. Coolidge: shirt-sleeves manager", IEEE Spectrum, vol. 21, no. 5 (May 1984), pp. 81-85.
  • J.E. Brittain, "William D. Coolidge and ductile tungsten", IEEE Industry Applications Magazine, vol. 10, no. 5 (September/October 2004), pp. 9-10.
  • J.E. Brittain, "Electrical Engineering Hall of Fame: William D. Coolidge", Proc. IEEE, vol. 94, no. 11 (November 2006), pp. 2045-2048.

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