Determine the shape of the Earth 200 years ago with gravity
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 to me due to th