American inventor who was a pioneer in radiotelephony and a noted teacher of communication engineering.

The second of three sons of a farm family, Pierce grew up on a cattle ranch and fared well enough in the modest rural schools of central Texas to graduate (1893) after three years at the University of Texas, Austin. He taught in rural secondary schools in his native central Texas until 1898, when he won a fellowship to Harvard University. There he turned to physics, and after receiving his Ph.D. in 1900 he studied for a time in the laboratory of Ludwig Boltzmann in Leipzig, Ger.

Pierce returned to the United States and took up teaching at Harvard, where he served from 1903 to 1940. Upon the establishment of Harvard's Cruft High Tension Electrical Laboratory in 1914, he became its director. There he did work that led to the practical application of a variety of experimental discoveries in piezoelectricity and magnetostriction. He developed the Pierce oscillator, which utilizes quartz crystal to keep radio transmissions precisely on the assigned frequency and to provide similar accuracy for frequency meters.

Pierce was an exceptional teacher, and he offered a number of the earliest courses in radio communications. This pioneering teaching, together with his many influential publications on radiotelegraphy and electroacoustics, led to his being credited with building the scientific foundations of electrical communication. His other accomplishments include the mathematical calculation of the radiation properties of radio antennae; invention of the mercury-vapour discharge tube, which was the forerunner of the thyratron; invention of a method of recording sound on film; and work on the magnetostriction of nickel and nichrome, which has important applications for underwater signaling and submarine detection. His later work concerned sound generation by bats and insects, a field in which he was still active and publishing in 1948.

Pierce wrote two classic textbooks, Principles of Wireless Telegraphy (1910) and Electric Oscillations and Electric Waves (1919).