Percy L. Spencer
Percy L. Spencer was an American inventor and engineer, best known for his development of the microwave oven. Born in 1894 in Maine, Spencer faced significant hardships in his early life, including the loss of his father and abandonment by his mother. He left school at a young age to contribute to his family’s income and eventually self-educated himself in electrical engineering. During his service in the Navy, Spencer honed his skills as a radio engineer, which led to a successful career at Raytheon, where he initially worked with vacuum tubes.
His pivotal moment came when he discovered that microwave radiation could cook food, after noticing a candy bar had melted in his pocket during an experiment. This serendipitous finding spurred him to develop the first microwave oven, which was introduced to the public in 1947 as the Radarange. Spencer held over 150 patents by the end of his career and was recognized as a leading expert in microwave technology. Despite his lack of formal education, he was inducted into the National Inventors Hall of Fame in 1999, highlighting his significant impact on modern cooking and food preparation. Spencer’s work exemplifies the transition of military technology to consumer use, fundamentally changing dietary habits and culinary practices.
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Percy L. Spencer
American electrical engineer
- Born: July 9, 1894
- Birthplace: Howland, Maine
- Died: September 8, 1970
- Place of death: Newton, Massachusetts
Spencer is best known as the inventor of the microwave oven, one of the most popular household time-, labor-, and energy-saving devices of the twentieth century.
Primary fields: Electronics and electrical engineering; household products
Primary invention: Microwave oven
Early Life
The childhood of Percy Lebaron Spencer was one of tragedy and deprivation. He was born in a Maine farming community in 1894. His father died when he was eighteen months old, and his mother abandoned him soon afterward, leaving the young Spencer with an impoverished aunt and uncle. At age twelve, Spencer left elementary school to work in a local paper mill to bring much-needed extra income into his household. Four years later, after learning that the mill was to become electrified, he volunteered to assist with installing the electrical system, which provided him with a practical education in electrical engineering.
Inspired by reports of the efforts of wireless telegraphers to rescue victims of the Titanic disaster in 1912, Spencer developed an interest in radio, a technology then in its infancy. Joining the Navy as a teenager, he feigned a formal education by teaching himself from textbooks in order to gain admission to radio school. Spencer excelled as a radio engineer and was appointed supervisor of a crew of naval radio operators during World War I. Following his discharge from the Navy, Spencer went to work in the burgeoning radio industry, taking a job with the Radio Corporation of America (RCA) in 1918. In 1922, the Raytheon Company, an early manufacturer of radio components, hired Spencer at the suggestion of his brother John, an engineer with the company.
Life’s Work
During his time at Raytheon, Spencer worked extensively with vacuum tubes, an essential component of early radios. In 1925, after leading radio manufacturer RCA increased the operating voltage of its radios, rendering Raytheon tubes obsolete, Spencer quickly developed a tube compatible with the new radios, saving the most profitable product manufactured by the company and facilitating Raytheon’s growth during the 1920’s. During the 1930’s, he developed a more efficient vacuum tube for radios that helped sustain the company during the Great Depression. Driven by a seemingly insatiable curiosity, Spencer developed a reputation as a tireless worker who often spent hours in the laboratory dismantling and reassembling parts and devices to familiarize himself with their inner workings and to devise ways of improving them. Devices or materials that other engineers discarded as waste were often a source of inspiration and knowledge for Spencer, who in the course of his research discovered that broken vacuum tubes were capable of emitting large amounts of concentrated photoelectric energy, a discovery that aided the development of cathode-ray tubes for televisions in the 1930’s.
During World War II, Spencer worked extensively with radar, a technology still in its experimental stages that involved long-distance detection of airplanes, artillery, and other objects through the use of concentrated electromagnetic waves fired over long distances that would reflect from the objects and reveal them as images on a display screen. The key component of these radar devices was a magnetron, a high-powered vacuum tube from which electromagnetic waves were emitted. As the war intensified, an increasingly urgent demand for the deployment of radar units in the field went unfulfilled because of the slow nature of the production process. At the behest of U.S. and British military forces, Spencer developed a method of mass-producing magnetrons through an innovative laminating process that enabled the tubes to be fashioned rapidly from thin sheets of metal. This process resulted in a dramatic increase in the use of radar units by Allied forces toward the end of the war. In the process of improving production techniques, Spencer also made several improvements to radar devices that rendered them more accurate and effective. In addition, he drew upon his knowledge of radar to develop the proximity fuse, a small radarlike device that could be placed in artillery shells to ensure their detonation at the proper distance from their targets. For his efforts, the Navy presented Spencer with its highest civilian honor, the Distinguished Public Service Award.
Spencer continued experiments with the new technology following the end of the war, winning critical peacetime defense contracts that helped to keep his company afloat during the postwar era. In 1945, Spencer, working to develop an improved radar device, conducted an experiment using a high-powered magnetron. During the experiment, he discovered that the candy bar that he was carrying in the pocket of his lab coat had melted. Intrigued, Spencer subsequently placed a quantity of popcorn in front of the magnetron and watched as it quickly popped. He later placed the magnetron inside a metal box to concentrate the waves further and placed an egg beside the box; the egg reportedly exploded in the face of his assistant as the magnetron heated it from within. Spencer had demonstrated that the radio waves capable of detecting metal objects from a distance by bouncing off them were absorbed by most nonmetallic substances, producing heat from within the substances through a process known as dielectric heating, in which microwave radiation accelerates the motion of molecules within a substance and heat is produced by friction from the contact between the molecules.
Intrigued by the promise of his initial experiments, Spencer began working toward development of a workable device for cooking food with microwave radiation. The primary obstacle to developing this device was devising a means of controlling the power emitted by the magnetron to avoid overheating the food being cooked, a problem that Spencer resolved with characteristic resolve and urgency. Having devised a suitable prototype, Spencer filed for a patent for the microwave oven on October 8, 1945. In 1947, Raytheon introduced the Radarange, the first microwave oven marketed to the public. The company paid Spencer a token fee of two dollars for rights to the patent but soon promoted him to vice president, a position that he would hold for the remainder of his life. In 1958, Raytheon honored Spencer by dedicating a research laboratory to him in Burlington, Massachusetts. Spencer Laboratory remained an active research facility until 1965 and was still owned and occupied by Raytheon at the end of the twentieth century.
The holder of more than 150 patents by the end of his career, Spencer remained active in his field following his retirement from full-time research, continuing as a vice president and senior consultant at Raytheon until his death in 1970 at age seventy-six. Many of his obituaries scarcely mentioned his invention of the microwave, citing instead his relatively obscure work in defense and vacuum tube technology. In 1999, Spencer was inducted into the National Inventors Hall of Fame.
Impact
Despite lacking a high school education, Spencer became recognized worldwide as one of the leading experts in microwave technology and the inventor of the most widely known and frequently used device to utilize the technology, the microwave oven. As a self-taught inventor who developed his inventions in corporate laboratories, Spencer is also symbolic of the shift in focus from the individual to the corporation that characterized technological research in the developed world during the early twentieth century. His invention of the microwave oven is an early example of the adaptation of military technology to consumer applications that would become a dominant force in the U.S. economy during the latter half of the twentieth century. By providing humans with an alternative means of preparing food, the microwave oven produced changes in cuisine, diet, and eating habits, creating demand for new products geared toward the new technology such as microwave-safe cookware and foods prepared and packaged for microwave cooking.
Bibliography
Earls, Alan R. Raytheon Company: The First Sixty Years. Charleston, S.C.: Arcadia, 2005. Discusses Spencer’s contribution to the success of the company and the development of numerous products, including the microwave oven.
Gupta, Manoj, and Eugene Wong Wai Leong. Microwaves and Metals. Hoboken, N.J.: John Wiley & Sons, 2007. This microwave engineering text includes images of Spencer’s original patent application, a brief discussion of the invention of the microwave oven, and an overview of practical industrial applications of microwave oven technology.
“How Amana Started Cooking with Electronics.” Electronics 50 (April 14, 1977): 99. The story of how a Raytheon-owned manufacturer improved upon existing technology to develop one of the first viable household microwave ovens in the 1960’s.
Kulman, Linda. “Ode to the Microwave.” U.S. News and World Report, April 7, 1997, 16. This brief historical synopsis of the microwave contains information about Spencer and the microwave oven not mentioned in similar sources.
Murray, Don. “Percy Spencer and His Itch to Know.” Readers Digest, August, 1958, 114. One of the most detailed sketches available on the life and work of Spencer. Discusses his childhood and early career.