Fritz Gassmann was born on July 22, 1899, in Zurich, Switzerland, and died there on April 9, 1990. Gassmann qualified as a primary schoolteacher in 1919 and went on to study mathematics at the Swiss Federal Institute of Technology (ETH Zurich). This culminated in a mathematics Ph.D. in 1925 and in his habilitation in geophysics in 1928, enabling him to lecture at the institute. Gassmann’s interest in geophysics began when the field was still in its infancy and he was in a two-year stint as an assistant at the Swiss Meteorological Institute, in the Department for Earthquake Studies.
From 1928 through 1942, Gassmann had a remarkable dual career. While lecturing in geophysics at ETH, he also taught mathematics at Aarau Canton High School, where he became rector in 1937. In 1942, Gassmann was elected associate professor of geophysics at ETH, allowing him to concentrate full time on research. From 1952 through 1969, he was a full professor at ETH and head of its Geophysics Department, which he had founded in 1934.
Throughout his career, Gassmann published research on a wide variety of topics, including elasticity and elastic waves, earthquake analysis and applied seismology, gravimetrics, and earth magnetism. His main interest, however, was in seismology and seismic prospecting. In 1960, Gassmann and his coworker, Max Weber, published a textbook, Einfuehrung in die angewandte Geophysik (Introduction to Applied Geophysics).
Most of Gassmann’s papers were written and published in German, and because of that and his reluctance to attend conferences, recognition for his
Figures & Tables
In this chapter, we give a brief synopsis of each of the classic papers referred to in this collection. Where relevant, we reproduce the basic equations, recast in modern notation. Supporting works also are referred to. They are listed in the “General References” section.
Table 1 is a quick outline of the key contributions of each paper reprinted in this book.
Robert Hooke, “Potentia Restitutiva, or Spring” (Oxford, 1678)
The article by Robert Hooke, “Potentia Restitutiva, or Spring,” contains the statement of the proportional relation between stress and strain universally referred to as Hooke’s law. Although the English language has evolved somewhat since 1678, the article does not require translation. Hooke describes a variety of experiments, accompanied by illustrations, confirming the stress/strain relation over a wide range of applied loads. He emphasizes the great generality of his results.
Based on his experimental work from 1660 onward, Hooke first published his law in 1676 in the form of an anagram in Latin,
which he later revealed to be “ut tensio sic vis.” Roughly translated, this means “as the force, so is the displacement” (Love, 1911; Boyce and DiPrima, 1976).
In his treatise, Hooke examined the behavior of springs, so his first casting of the equations dealt with the restoring force on a spring, for a given displacement: