William David Coolidge was born in Hudson, Massachusetts, the son of a farmerand a dressmaker. As a young boy, he worked in a shoe factory to help support his family. After attending public schools, Coolidge funded his own collegeeducation by borrowing money and earning scholarships and fellowships. Witha degree from the Massachusetts Institute of Technology (MIT), Coolidge wentto Germany to study physics. After earning his Ph.D. with high honors, he returned to MIT to do research. Although Coolidge was content there, he was lured in 1905 to General Electric Company's research laboratory, which offered todouble his MIT salary. Coolidge had avoided a career in industry after experiencing factory work, but General Electric (GE) promised him freedom to pursue his own interests as well as the company's commercial research goals. As itturned out, he remained at the lab for his entire career, like his GE colleague Irving Langmuir.
In just a few years, Coolidge solved one of the greatest technological problems of the time--developing a superior filament for incandescent light bulbs.Early electric light bulbs used carbon filaments, which were not only delicate to handle but were also limited in the amount of light they could produce.Scientists knew that tungsten, the metal with the highest melting point, would perform better than carbon; but because tungsten is brittle, no one could figure out a way to make filaments from it. Coolidge invented a process for making tungsten ductile, or capable of being drawn into fine wire for filaments. Modern electric light bulbs are still manufactured this way. Continuing hisresearch with tungsten, Coolidge invented an X-ray tube that is still used by doctors and dentists today. His revolutionary tube was based on a tungsten"target," which is bombarded under high vacuum by a stream of electrons to produce X-rays. Coolidge's tube allowed much more precise control over the X-ray wave length and could also accommodate much higher voltages. Patented in 1913, the Coolidge tube introduced X-ray technology into the worlds of industryand medicine. During World War I, Coolidge collaborated with Langmuir on thedevelopment of the first successful submarine detection system. Coolidge frequently incorporated many techniques used in nuclear research to produce a total of eighty-three patents. In 1932 he became director of GE's lab, earningrespect for his modesty and calm authority. He postponed his retirement until1945 in order to work throughout World War II. Coolidge lived to the age of102, continuing to enjoy hobbies such as travel and photography.