Bullard, Sir Edward (1907-1980), an English geophysicist, made a major contribution to the study of Earth’s magnetism and the generation of heat inside the planet. He theorized that Earth’s magnetic field results from convection currents in the molten (melted) part of Earth’s core. Convection currents are patterns of circulation in a fluid that result from the tendency of warm material to rise and cool material to sink. Bullard suggested that convection currents in the core produce electric currents that generate the planet’s magnetic field. See Magnetism (Earth) .
Bullard carried out important geophysical research in the 1930’s. This work led to the first useful measurement of heat flow from Earth’s interior in 1940. During World War II (1939-1945), he was an experimental officer with the Royal Navy, working on degaussing (neutralizing the magnetic field) of ships to protect them from German magnetic mines (see Gauss ). In 1946, he became professor of physics at the University of Toronto, where he developed his theory of Earth’s magnetism. From 1950 to 1955, he was director of the United Kingdom’s National Physical Laboratory in London. He used the laboratory’s early computer to make numerical calculations concerning his theory of Earth’s magnetism. In 1955, Bullard became assistant director of the Department of Geodesy and Geophysics at Cambridge University. He became professor and head of the department in 1964. The department achieved a high international reputation under his leadership. He retired in 1974 and moved to La Jolla, California, where he continued his research at the Scripps Institution of Oceanography, University of California.
Edward Crisp Bullard was born on Sept. 21, 1907, in Norwich, England. He attended Clare College of Cambridge University, where he graduated in physics in 1929 and earned a doctorate in geophysics in 1935. From 1936 to 1943, he was Smithson Research Fellow of the Royal Society, one of the world’s foremost scientific organizations. In 1941, Bullard became a Fellow of the Royal Society. He was knighted in 1953. Bullard gave his name to the geophysical laboratories at Cambridge University and to a fracture zone under the Atlantic Ocean. He died in La Jolla on April 3, 1980.
