Kim Williams invited me to publish a selection of conferences which I had presented at various occasions during my stay at the UCL and elsewhere. She selected some papers which refer to topics on the history of science, especially on the history of mechanics. My occupation with the history of science began through the mathematician Andreas Speiser, my uncle, at the time the General Editor of the Opera Omnia of Leonhard Euler, who invited me to edit volume III, 5 of the Opera, containing Euler s work on physical optics. I accepted this offer with great pride and indeed, the task gave me much...