The catalogue of the library of Count Paul Riant, published in two parts at Paris in 1899, also contains the titles of a great number of books and pamphlets which relate to the subject under discussion. Most of this material has been transferred to the Ottoman collection of the Library of Harvard University, through the generosity of Messrs. J. R. Coolidge and A. C. Coolidge,—a gift, it may be added, that has made the preparation of the present treatise possible. There are also many titles on early Ottoman history in the catalogue of Charles Schéfer’s Oriental library (published at Paris in 1899), from which the same donors have contributed 445 volumes to the Harvard Ottoman collection. The list given in the _Cambridge Modern History_, i. 700-705, in connection with Professor J. B. Bury’s chapter on “The Ottoman Conquest,” is fuller than most of those just mentioned. It omits some valuable authorities, however, such as Schiltberger, Menavino, Ramberti, and Busbecq. It is possible to get contemporaneous views of the Ottoman Empire at a date earlier than the beginning of the sixteenth century, though they are all incomplete. The first accounts go back to the battle of Nicopolis in 1396. Froissart (_Chroniques_, ed. Lettenhove, xv. 319 ff., Brussels, 1871), in a description of the battle and succeeding events which was based on accounts given by Jacques du Fay and Jacques de Helly, gives some idea of the Turkish army and the sultan. A better account for the present purpose is that by Johann Schiltberger (translated into English by J. B. Telfer, and published by the Hakluyt Society as _The Bondage and Travels of Johann Schiltberger_, London, 1879). Schiltberger, then a youth of sixteen, was taken prisoner at Nicopolis, and after serving as slave to Bayezid I for six years, was captured by Timur at the battle of Angora, 1402. He was retained as captive, not without important responsibilities and wide journeys, for twenty-five years longer, when he succeeded in escaping. It is a matter for regret that he says very little of his life at the sultan’s court, since he held a position which corresponded to that of page in later times.