Fleming, John Adam (1877–1956)

US geophysicist. Long associated with the Department of Terrestrial Magnetism of the Carnegie Institution of Washington, DC, he designed several geomagnetic observatories. He made important inventions in the field of geomagnetism and contributed to research in solar and lunar physics.

He was born in Cincinnati, Ohio. He joined the Department of Terrestrial Magnetism of the Carnegie Institution of Washington, DC, became its director, and continued to serve as an adviser in international scientific relations after his retirement. During his directorship, he designed geomagnetic observatories in Huancayo, Peru, Watheroo, Australia, and Kensington, Maryland. He took charge of the Institution's World War II contracts dealing with radio communications, ordnance devices, magnetic instruments, and ionospheric research to advance knowledge of the earth's magnetic field. He was one of the first officers of the American Geophysical Union, serving as general secretary and editor of their periodical. He expanded the field of geomagnetism by inventing or modifying both terrestrial and oceanographic geomagnetic instruments, and designing innovative isomagnetic world charts.