from E.Voss 19 May 1989; Birth year (in: Histoire généalogique et héraldique des pairs de France:11: 12. 1831, https://books.google.com/books?id=-MIElz1osd4C&printsec=frontcover#v=onepage&q=de%20Foucault&f=false ) & Death year (in Poiret, Hist. Philos. Pl. Eur. 3: 406. July 1826) (via David Hollombe)