The Department of Terrestrial Magnetism of the Carnegie Institution in Washington, D.C., was established in 1904 to solve two puzzles: the origins of the geomagnetic and the geoelectric fields. For the first, the DTM gathered data on secular variation, magnetic “storms,” and similar phenomena. By the 1930s the program had produced masses of observations but no solutions.
Under the leadership of E. A. Johnson and A. G. McNish, DTM in the late 1930s took up a new and promising approach—the use of paleomagnetic results to resolve two major disputes. One centered on the origin of the geomagnetic field; the other, on the possibility of continental drift. By the 1940s DTM had become the preeminent center for research in paleomagnetism. By the late 1950s that research had virtually ceased at DTM. Elsewhere, such a program in the hands of others was by then achieving considerable success.