Helmut Landsberg, born February 9, 1906 in Frankfurt/Main and educated there, received his Sc.D. in Geophysics (1930) under the guidance of Beno Gutenberg, who in those days opened new pathways to seismology. After Gutenberg left, in 1931, for Pasadena/ Cal., he became responsible for the seismic observatory at the Little Feldberg (801 m) in the Taunus Mountains. I remember us as a group of freshmen walking with him through the bright green spring forests up to his broad hill, in order to have a closer look at these highly sensitive instruments measuring the minute motions of the solid rocks underfeet, triggered by far-distant crustal movements or by the roaring waves at the Norwegian coast. Already at this time he impressed all of us by his pertinent sarcastic, but never offending remarks and his good sense of humour.
His scientific interests were quite broad, as was then the habit of the University of Meteorology and Geophysics at Frankfurt, headed by Franz Linke, himself pioneering in atmospheric radiation and electricity, and bioclimatology. So he tried with us the multitude of new instruments developed at this time to count condensation nuclei and atmospheric ions, to measure infrared and ultraviolet radiation and the atmosphere's cooling power on man. In touch with the physician W. Amelung he developed also there his interest on bioclimatology which he maintained until his death. This successful occupation at a lively multi-faceted institute came suddenly to an end, when -during a period of very high unemployment and economic crisis -Nazi forces took possession of the Government. At his own risk, Linke tried seriously to protect him, to hide him during several months at the lonely observatory but realizing very truly the situation he decided to emigrate (1934) to the United States.
After some difficulties he found a suitable position at Pennsylvania State College. In contrast to many of his colleagues, he maintained his links to Linke -several of his papers and reviews were published in his 'Bioklimatische Beibl~tter' of the 'Meteorologische Zeitschrift' until 1940. Here we read with amusement his essay (1938, pp. 66-68) on bed temperatures, when he measured, during 100 nights in fall and early winter, maximum and minimum temperatures in his bed, in comparison to the temperatures outside in a well ventilated room.
The most important one of his many publications at this time was his comprehensive, well-founded paper on 'Atmospheric Condensation Nuclei' (Ergebnisse der kosmischen Physik 3, 1938). Since 1935, the German Weather Servive initiated a network of Aitken measurements in this country; we expected then (but in vain) to obtain an objective index of atmospheric pollution. When comparing these data, Landsberg's masterful review was of considerable help. It was only after the war, when Christian Junge, also from the Frankfurt Institute, found a solution in putting the particle size spectrum into Climatic Change 9 (1986) 261-262. ~) 1986 by 1). Reidel Publishing Company.