On December 26, 1861, German geophysicist Emil Johann Wiechert was born. Wiechert made many contributions to both fields, including presenting the first verifiable model of a layered structure of the Earth and being among the first to discover the electron. He invented the “inverted pendulum” seismograph, (an improvement still incorporated in today’s instruments), with which he was able to detect some of the Earth‘s inner structure. He suggested the Earth has an inner, dense core of nickel-iron metal which had settled to the center like iron settles from slag on the hearth of an iron mill.
Emil Wiechert attended the University of Königsberg and earned his Ph.D. in 1889. One year later, Wiechert received his Habilitation in Physics and by 1896, he had achieved the title of Professor. While still at Königsberg, Emil Wiechert investigated the nature of X-rays. He managed to became the first scientist to discover that cathode rays are made up of particle streams. While he was able to measure the Mass-to-charge ratio of these particles, Wiechert failed to explain that these particles were a new type of elementary particle – the electron.
In 1896, he published the first verifiable model of the Earth’s interior as a series of shells. Wiechert concluded that difference between the density of the Earth’s surface rocks and the mean density of the Earth meant that the Earth must have a heavy iron core. In 1914, building on Wiechert’s foundations, Beno Gutenberg as one of Wiechert’s students discovered the three-layered Earth.
During the late 1890s, Emil Wiechert was invited by Felix Klein to found the world’s first Institute of Geophysics. There, Wiechert also became the world’s first Professor of Geophysics. During his career, Wiechert wrote numerous scientific papers and pioneered a work on how seismic waves propagate through the Earth. Further, Wiechert developed an improved seismograph and created the field of geological prospecting using small, artificially-created earthquakes.
References and Further Reading:
- Emil Wiechert Short Biography
- Emil Wiechert (1861–1928): Esteemed seismologist, forgotten physicist
- Emil Wiechert at Wikidata