When the earlier editions of this book were published, I was aware of the existence of a collection of documents relating to La Salle, and containing important material to which I had not succeeded in gaining access. This collection was in possession of M. Pierre Margry, director of the Archives of the Marine and Colonies at Paris, and was the result of more than thirty years of research. With rare assiduity and zeal, M. Margry had explored not only the vast depository with which he has been officially connected from youth, and of which he is now the chief, but also the other public archives of France, and many private collections in Paris and the provinces. The object of his search was to throw light on the career and achievements of French explorers, and, above all, of La Salle. A collection of extraordinary richness grew gradually upon his hands. In the course of my own inquiries, I owed much to his friendly aid; but his collections, as a whole, remained inaccessible, since he naturally wished to be the first to make known the results of his labors. An attempt to induce Congress to furnish him with the means of printing documents so interesting to American history was made in 1870 and 1871, by Henry Harrisse, Esq., aided by the American minister at Paris; but it unfortunately failed. In the summer and autumn of 1872, I had numerous interviews with M. Margry, and at his desire undertook to try to induce some American bookseller to publish the collection. On returning to the United States, I accordingly made an arrangement with Messrs. Little, Brown & Co., of Boston, by which they agreed to print the papers if a certain number of subscriptions should first be obtained. The condition proved very difficult; and it became clear that the best hope of success lay in another appeal to Congress. This was made in the following winter, in conjunction with Hon. E. B. Washburne; Colonel Charles Whittlesey, of Cleveland; O. H. Marshall, Esq., of Buffalo; and other gentlemen interested in early American history. The attempt succeeded. Congress made an appropriation for the purchase of five hundred copies of the work, to be printed at Paris, under direction of M. Margry; and the three volumes devoted to La Salle are at length before the public.