French physicist (1791–1820), and co-discoverer, with Pierre Dulong, of Dulong and Petit's law, which states that, for a solid element, the product of relative atomic mass and specific heat capacity is approximately constant. ALS in French, one page, 8 x 10.5, October 31. Letter to Marquis de Lafayette regarding his relative in the Navy. In part, “My relative—Prosper Dumont…there yesterday Sunday. When he left your house, he received an important letter following which his trip to the United States…I ardently wish that you would not have had taken care of this also since the recommendations that you were kind enough to promise me will now be useless to him. In case that you would have had the kindness to write for him I also extend my sincere thanks…I always regret to take you away to take care of me or my relatives concerning public affairs in which your intervention is more necessary to me than ever and it would be for me true sorrow to have abused needlessly of these precious moments. Please General, accept our apologies as well as the tribute of my tender veneration that I personally convey to you.” In very good condition, with light mailing folds and some edge wear, creasing, and paper loss to right edge, lightly affecting several letters of text. RR Auction COA.
