I don't think the final "s" in Descartes is pronounced. See, e.g., https://youtu.be/K9qK7qNgXS8 and http://ceadserv1.nku.edu/longa/classes/2009fall/mat305/resources/pronunciation.html
Also, your first mathematician would more commonly be called "von Mises" rather than just "Mises". (Just like we speak of von Neumann rather than of Neumann.)