Early History of Magnetic Resonance

In the title of this report, emphasis should be given to the word early. Some readers may even believe that "Pre-History" would be a better title than early history. The report will cover the period from 1921 to the first nuclear resonance absorption experiments of Purcell, Torrey and Pound and the first nuclear induction experiments of Bloch, Hansen and Packard even though from some points of view the history of magnetic resonance can be said to begin with the experiments that end this report. My interest in the history of magnetic resonance began with preparations for my Ph.D. final examination in 1939. Since mine was the first Ph.D. thesis based on nuclear magnetic, resonance, I feared that my examining committee would ask searching questions as to the origins of the ideas of magnetic resonance and of the molecular beam technique we used to detect the resonance transitions.