William David Coolidge

• Born: October 23, 1873
• Birthplace: Hudson, Massachusetts
• Died: February 3, 1975
• Place of death: Schenectady, New York

American engineer and physicist

Coolidge is best remembered for developing the ductile tungsten filament for lamps in 1911 and for creating the Coolidge tube, which improved the operation of Wilhelm Conrad Röntgen’s X-ray machine. He was also instrumental in developing polymeric materials and silicones that became essential components of electronics after World War II.

Primary fields: Electronics and electrical engineering; physics

Primary inventions: Ductile tungsten; Coolidge tube

Early Life

William David Coolidge was born in Hudson, Massachusetts, a town about twenty-five miles from Boston, on October 23, 1873. The son of Albert Edward Coolidge, a small farmer and shoemaker, and Mary Alice Shattuck Coolidge, a dressmaker, William was descended from an illustrious family that had arrived in Boston in 1630 and numbered among its members Calvin Coolidge, the thirtieth president of the United States. William, nicknamed Will, received his primary education in a humble one-room school where a single teacher worked hard to educate students of all grade levels together. The limits of his education, however, did not keep him from excelling; he showed exceptional abilities not only in his studies but also in sports and other outdoor activities, such as hiking and fishing. Fascinated by photography, Coolidge built his own camera while he was still in elementary school and outfitted a darkroom in his parents’ house; this childhood passion remained his most enjoyed hobby over the entire course of his life.

After finishing elementary school, Coolidge went on to Hudson High School, where he excelled in mathematics and physics, graduating as valedictorian of his class of thirteen students. Because of his family’s limited financial resources, after graduation he took a job in a factory that manufactured rubber garments instead of going to college. Fortunately, a friend suggested that he apply for a scholarship at the local college known as Boston Tech, which was, in fact, the Massachusetts Institute of Technology (MIT). His excellent high school grades combined with his mechanical and electrical skills won him the award, and in September, 1891, at age seventeen, Coolidge entered MIT. Studying electrical engineering, chemistry, physics, and modern languages, he was immediately impressed by his chemistry professor,Willis R. Whitney, who in turn was delighted to have such a dedicated student.

During the summer of his junior year at MIT, Coolidge earned an internship at Westinghouse Electric in Pittsburgh, Pennsylvania. His experience at Westinghouse taught him that he was not well adapted to conducting engineering research in a company setting; he was much better suited to laboratory experimentation. When he graduated in 1896, with the encouragement of Professor Whitney, Coolidge applied for a scholarship to go to Leipzig, Germany, to study physics under the guidance of Gustav Wiedemann and Paul Drude. Accepted into the program, he financed his adventure through a combination of a scholarship and money borrowed from a friend. The investment turned out to be a good one; in just three years, Coolidge completed his studies and received his doctorate in physics.

Life’s Work

With his impressive record at Leipzig, where he had earned his Ph.D. with the highest possible grade, Coolidge was offered a teaching position in the Physics Department at MIT. For the next five years, he taught, assisted professor of chemistry Arthur Amos Noyes, and continued to work with his mentor, Whitney.

Whitney was in charge of the new General Electric (GE) Research Laboratory in Schenectady, New York, and so was able to offer a position there to Coolidge, whose potential for research he had cultivated and highly respected. After a successful negotiation in which Coolidge secured a salary that was twice what he had been earning at MIT and gained the right to use half his time (and the laboratory’s equipment) for his personal research, Coolidge accepted the position. Beginning in 1905, one of his first projects focused on improving Thomas Alva Edison’s lamp; his work resulted in the creation of a light bulb that was three times more powerful than Edison’s. The profits that General Electric realized from this extremely popular innovation more than justified both Coolidge’s salary and the company’s massive investment ($116,000) in the construction of the laboratory.

Financially secure in his new position, on December 30, 1908, Coolidge married Ethel Woodward, the daughter of the president of a local bank. Their marriage produced two children, Elisabeth and Lawrence, but ended in tragedy when Ethel died in 1915 of an infectious disease. Soon after, Coolidge hired Dorothy Elisabeth MacHaffie, a nurse, to care for his two young children. Within a year, Coolidge married her.

At the laboratory, Coolidge continued to search for ways to improve the light bulb, experimenting with different substances to be used as filaments, until a lamp using tungsten was produced in Austria. Although the tungsten filament produced a very bright light, researchers in Europe and at General Electric were confronted with a major problem: The brittleness of the filament rendered the bulb extremely fragile. After three years of intense research, Coolidge discovered a method to make tungsten ductile (capable of being drawn out into a very thin wire or thread) at room temperature through the addition of 1 percent of thorium. The result was a flexible, durable filament that was so thin that a single pound of tungsten made a wire 8.5 miles long and would be sufficient to produce twenty-three thousand bulbs. This new incandescent lamp was produced in 1911.

Two years earlier Whitney had hiredIrving Langmuir, who had worked on heat transfer in gases at high temperatures. Langmuir suggested that Coolidge could double the light output of his bulbs by replacing the vacuum previously used with an inert gas. The collaboration between Langmuir and Coolidge resulted in the production of General Electric’s best-selling Mazda C light bulb.

In the months following the development of ductile tungsten, Coolidge explored its application to a variety of problems, employing it to replace platinum in telegraph keys, auto ignitions, and other equipment controls. His most significant discovery, however, came when he used the tungsten to make a source of X rays that was dramatically more dependable than previously available sources. Wilhelm Conrad Röntgen, a German physicist, had discovered X rays in 1895, and Coolidge had met Röntgen briefly when he was studying in Leipzig. There was a certain parallel between the development of the bulb Coolidge had worked on and the bulb that Röntgen used to produce X rays. Coolidge’s idea, for which he received a patent in 1913, was to replace the low-pressure gas in Röntgen’s X-ray-generating tube with a vacuum in which a thick tungsten filament, when heated by an electric current, would generate a continuous and ample stream of electrons. This invention, which became known as the Coolidge tube, was hailed as a breakthrough that could produce electrons “in the same quantity every second as a ton of radium.” The value of the Coolidge tube in improving X-ray diagnosis was immediately recognized by both physicians and the scientific community. Coolidge received the Rumford Prize of the American Academy of Arts and Sciences in 1914 for his experimental achievements on “ductile tungsten and its application in the production of radiation.”

With the onset of World War I, Coolidge and the GE Research Laboratory plunged into the vital scientific support of the war effort. Coolidge’s development of portable X-ray machinery immeasurably improved battlefield diagnoses of injuries and saved countless Allied lives, but his greatest contribution came when GE, the Submarine Signalling Company, and Western Electric collaborated to produce an effective submarine detection system based on sealed rubber binaural listening tubes—“C tubes”—that Coolidge produced. Supplied with these devices in 1918, Allied navies were able to end the dominance of German U-boats in the Mediterranean, an important factor in the ultimate Allied victory.

On November 1, 1932, after the economic pressures of the Great Depression had overwhelmed the retiring Willis Whitney, Coolidge became director of research at the GE Research Laboratory, where he took on the challenge of ensuring the laboratory’s survival in hard times. Through remarkably careful management, Coolidge succeeded, and by 1940, as the economy improved, he began to envision his own retirement. Unfortunately, world events interfered, and Coolidge decided to stay at his post for the duration of World War II. A member of President Roosevelt’s Advisory Committee on Uranium, Coolidge was involved in the development of the atomic bomb, bringing valuable practical engineering skills to the project. Coordinated with other institutions through the government’s Office of Scientific Research and Development, Coolidge and the GE Laboratory also contributed to the development of microwave radar as well as radar and radio countermeasures.

With the end of the war finally in sight, Coolidge finally retired on January 1, 1945. Retirement, however, did not end his intellectual activity. Blessed with remarkably good physical and mental health, Coolidge continued to visit the GE Laboratory, advising the next generation of researchers there until shortly before his death, at 101 years of age, in 1975.

Impact

Coolidge is remembered for his development of ductile tungsten and for the invention of the Coolidge tube, which revolutionized radiology; he is also remembered for his development of essential technological applications that helped to win both world wars. During his lifetime, Coolidge was awarded eighty-three patents and received numerous prestigious honors, such as the Washington Award of the Western Society of Engineers (1932), the John Scott Award granted by the City Trusts of the City of Philadelphia (1937), the Faraday Medal of the Institution of Electrical Engineers of England (1939), the Duddell Medal of the Physical Society of England (1942), the Franklin Medal of the Franklin Institute (1944), the first K. C. Li Gold Medal for the Advancement of the Science of Tungsten by Columbia University (1951), the Röntgen Medal (1963), and the Climax Molybdenum Wedgwood Medallion (1973). In 1972, Coolidge was the first recipient of an annual award named in his honor, the William D. Coolidge Award, presented by the American Association of Physicists in Medicine.

Even though Coolidge made such essential discoveries, he always stressed that they had been the fruits of intense labor by a team of researchers at the laboratory and could not possibly be attributed to his work alone. He was regarded by his colleagues as an honest, quiet, modest, and energetic man.

Bibliography

Evans, Harold. They Made America: From the Steam Engine to the Search Engine—Two Centuries of Innovators. Boston: Little, Brown, 2004. Chronicles the work of seventy American inventors and entrepreneurs, focusing on the impacts of their work and their roles as visionaries on the modern world.

Hughes, Thomas. A Century of Invention and Technological Enthusiasm, 1870-1970. Chicago: University of Chicago Press, 2004. Provides comprehensive information about inventors in the United States and the roles that prominent laboratories, such as General Electric Research Laboratory, have played in their discoveries.

Liebhafsky, Herman. William David Coolidge: A Centenarian and His Work. New York: John Wiley & Sons, 1974. Presents a detailed, complex portrait of Coolidge and his family, drawing on the scientist’s personal journals and papers. Particularly interesting are the notes that Coolidge took daily in his laboratory.

Miller, John. Yankee Scientist: William David Coolidge. Schenectady, N.Y.: Mohawk Development Service, 1963. Provides biographical information as well as discussion of Coolidge’s achievements and inventions.

Van Dulken, Stephen. American Inventions: A History of Curious, Extraordinary, and Just Plain Useful Patents. New York: New York University Press, 2004. Presents brief overviews of a large number of American inventions from two centuries of U.S. Patent Office records. Includes illustrations.