Sylvestre-François LACROIX (1745-1843), mathematician. - Autograph letter signed to the mathematician Louis Puissant (1769-1843). 1 p. in-8. Address on the back. He sends him a letter from M. Strum so that he can write his report. - Autograph letter signed to the bookseller Michaud. 2 pp. in-8. 30 May 1811. Letter about the articles he is writing for the Biographie universelle (Barrow, Bernoulli, etc.).