The last years at the institute

World War II breaks out not long after the publication of P' and this means that the seismological stations in Greenland come under American control. It becomes difficult to maintain contact with international colleagues and in terms of research it is a flat time for Inge Lehmann and seismology.

The only real man

After the war, she can resume her international connections and the success of P' and the discovery of the Earth’s inner core in 1936 means, among other things, that Inge Lehmann can now work as a lecturer all over the world.

The Australian-American professor of seismology Bruce Bold later characterises Inge Lehmann as an absolutely central figure for international seismology in the period after P'. 

But back at the institute her relationship with the director Niels E. Nørlund gets worse and worse.

They both have big personalities and Lehman, in particular, is no diplomat. For example, it can hardly be well received that she refers to herself as “the only real man in the place”.

All in all, Inge Lehmann has an increasingly strained relationship with the Geodetic Institute and 25 years later – in 1978 - when she is asked to write an article for a festschrift in celebration of the institute’s 50^th anniversary, she flatly refuses.   

Invitation to the United States

In 1951, Maurice Ewing from the Lamont Geological Observatory in New York visits Inge Lehmann and the seismological stations in Copenhagen.

He invites her to Lamont, where she will help research a new surface wave called Lg.He is a close friend and values her unique talent in reading seismograms. 

Inge Lehmann leaves the following year, in 1952, and spends several months busily occupied with describing the new wave and she brings European seismograms to compare with the American observations.

Recognition

In this way, she demonstrates significant variations in the European and American measurements and it turns out to reflect differences in the Earth’s upper mantle beneath the continents.

In the United States, Inge Lehmann experiences recognition in a way that she is not used to back home in Denmark. Seismology had been an entirely new field when she started as Denmark’s first seismologist 27 years earlier, but by the early 1950s the field was established and they realised, the Americans in particular, how valuable seismological studies could be in relation to researching, among other things, subterranean nuclear tests.

Inge Lehmann is treated like a queen in the United States. She travels by military aircraft and Maurice Ewing does everything to get her over there and make sure she has a good stay.

Was she slighted?     

The story goes that Inge Lehmann applies for a position as a professor of geophysics at the University of Copenhagen the same year as the trip to the United States, in 1952 – but she is passed over.  

Perhaps it is because she is a woman or perhaps it is because at 64 she is too old and too close to retirement – which in any case is the official explanation from the Niels Bohr Archive.

In any case, it is Bohr’s candidate that is chosen and the relationship between the great researchers, Inge Lehmann and Niels Bohr, remains unclear.

But by the following year, she had at least had enough of her work and the Geodetic Institute and in 1953 she stops as state geodesist and retires – five years early.