In 1925 Lehmann became an assistant to the geodesist Niels Erik Nørlund, who assigned her the task of setting up seismological observatories in Denmark and Greenland.
In a paper titled P&apos; (1936),[REF] Lehmann was the first to interpret P wave arrivals-which inexplicably appeared in the P wave shadow of the Earth's core-as reflections from an inner core, for example from the strong 1929 Murchison earthquake [REF].