DeepEarthScience

A colleague of mine pointed me to a PhD dissertation of Petrus van Galen. He wrote this dissertation in 1830 and two copies can be found in the Tresor of the TU Delft Library. The title of this dissertation is “ Disputatio Mathematica Inauguralis d e Pendulo Ejusque Applicatione ad Telluris Figuram Determinandam ”. Loosely translated: A Mathematical Essay about the Pendulum and its Application to Determine the Figure of the Earth. Of course, as soon I heard about this, I made an appointment with the librarian responsible for the collection in the Tresor for a viewing session. I also found a  link  in Google books, showing almost the complete dissertation, but I wanted to smell the old pages. Furthermore, the appendices of the dissertation were not scanned properly, so the data, that Petrus van Galen used, were not yet available to me. A week later, I cycled to the Library (appointed as one of the 10 most beautiful libraries of the world and known very well t...

On a cold winter day, 21 November 1934, professor Vening Meinesz turned on his pendulum apparatus. Just a few minutes ago, the submarine K-XVIII dived to a depth of 30 meters [1]. A t these depths, t he motion of the surface waves was dampened such that it did not influence the delicate measurements done by the professor. This particular observation would mark the 500th measurement, observing the tiniest changes in the Earth's gravity field. This new gravity dataset would reveal many new mysteries of our home planet and would be the life’s work of Vening Meinesz. It is all documented in scientific publications of four volumes called  Gravity Expeditions at Sea , followed by a fifth volume with gravity observations done by his students. Along these expeditions, the professor had brought his specially designed pendulum apparatus, or folklorised by the sailors on board the many submarines: Het Gouden Kalf  (the Golden Calf). The pendulum apparatus of Vening Meinesz, also kn...