27, 1901. All four of his grandparents were born in Norway and subsequently emigrated to the United States. His father, Anthony G. Tuve, was president of Augustana College and his mother, Ida Marie Larsen Tuve, taught music there. A next-door neighbor and contemporary was Ernest Orlando Lawrence. The two boys played together and at age thirteen began to build telegraphic and later radio equipment. They were among the early radio amateurs.

After Tuve's father died in the influenza epidemic of 1918 the family moved to Minneapolis, where Merle attended the University of Minnesota, graduating in physics in 1922 and obtaining a master's degree in 1923. Following a year at Princeton, where he was an instructor, Tuve went to the Johns Hopkins University to work for his doctorate. While at Minnesota Merle developed a close friendship with Breit, a theoretical physicist who moved in 1924 to the Department of Terrestrial Magnetism of the Carnegie Institution of Washington. After Tuve's arrival at Johns Hopkins, Breit sought his collaboration in a possible effort to study the ionosphere.

At the time, the electronics equipment available was primitive and relatively insensitive. To demonstrate the existence of the ionosphere it would be necessary to find evidence that radio signals arrived over at least two paths, a ground wave and a sky wave. To take an example: if a receiver were set up 13 miles from a radio transmitter, and if the ionosphere layer were 100 miles above the receiver, two pulses should arrive, a direct pulse and then, a millisecond later, a reflected pulse. If the height of the ionized or reflecting layer were increased or decreased, then the difference in time of arrival of the two pulses would change correspondingly. Tuve devised the necessary detecting equipment and Breit and Tuve were able to use a Naval Research Laboratory oscillator for their source of radiation. They observed



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