TheGassmannstory.PDF

The Gassmann story PETER GRETENER, University of Calgary, Alberta, Canada Fritz Gassmann published his classic paper “Elastic waves in our times. through a packing of spheres” in GEOPHYSICS in 1951. At that Gassmann, contrary to many colleagues, never sat next time I was a member of a motley group of Gassmann’s to God. He was a shy man and played his cards close to his graduate students—one mathematician, one theoretical chest. As a result, some of the following comments are some- physicist, one experimental physicist, one civil engineer, what speculative. and two geologists (there was no undergraduate geophysics Gassmann’s interest in geophysics was triggered by a program in those days)—who were blissfully unaware of two-year stint, after graduation, at the Swiss Federal Earth- its fundamental significance. This is hardly a surprise con- quake Service. Later he taught mathematics at the Aarau sidering our inexperience. high school (most high-school teachers in Switzerland had The broad background of our graduate student group PhDs), and Gassmann continued his activities in geophysics proved helpful in many ways. Just two incidents may illus- as a hobby. In 1928 he started giving lectures on geophysics trate the point. The other geologist had to deal with a well- at the Swiss Federal Institute of Technology (ETH). In 1942 rounded clastic sediment, and he figured that he should be he was elected associate professor and head of the Institut able to deduce the grain size distribution from just a single für Geophysik at ETH. For a country almost devoid of nat- thin section or polished surface. He enlisted the help of