When I returned home from China in 1876, I was introduced to Colonel HENRY YULE, at the India Office, by our common friend, Dr. REINHOLD ROST, and from that time we met frequently and kept up a correspondence which terminated only with the life of the great geographer, whose friend I had become. A new edition of the travels of Friar Odoric of Pordenone, our “mutual friend,” in which Yule had taken the greatest interest, was dedicated by me to his memory. I knew that Yule contemplated a third edition of his _Marco Polo_, and all will regret that time was not allowed to him to complete this labour of love, to see it published. If the duty of bringing out the new edition of _Marco Polo_ has fallen on one who considers himself but an unworthy successor of the first illustrious commentator, it is fair to add that the work could not have been entrusted to a more respectful disciple. Many of our tastes were similar; we had the same desire to seek the truth, the same earnest wish to be exact, perhaps the same sense of humour, and, what is necessary when writing on Marco Polo, certainly the same love for Venice and its history. Not only am I, with the late CHARLES SCHEFER, the founder and the editor of the _Recueil de Voyages et de Documents pour servir à l’Histoire de la Géographie depuis le XIIIᵉ jusqu’à la fin du XVIᵉ siècle_, but I am also the successor, at the École des langues Orientales Vivantes, of G. PAUTHIER, whose book on the Venetian Traveller is still valuable, so the mantle of the last two editors fell upon my shoulders. I therefore, gladly and thankfully, accepted Miss AMY FRANCIS YULE’S kind proposal to undertake the editorship of the third edition of the _Book of Ser Marco Polo_, and I wish to express here my gratitude to her for the great honour she has thus done me.[1] Unfortunately for his successor, Sir Henry Yule, evidently trusting to his own good memory, left but few notes. These are contained in an interleaved copy obligingly placed at my disposal by Miss Yule, but I luckily found assistance from various other quarters. The following works have proved of the greatest assistance to me:—The articles of General HOUTUM-SCHINDLER in the _Journal of the Royal Asiatic Society_, and the excellent books of Lord CURZON and of Major P. MOLESWORTH SYKES on Persia, M. GRENARD’S account of DUTREUIL de RHINS’ Mission to Central Asia, BRETSCHNEIDER’S and PALLADIUS’ remarkable papers on Mediæval Travellers and Geography, and above all, the valuable books of the Hon. W. W. ROCKHILL on Tibet and Rubruck, to which the distinguished diplomatist, traveller, and scholar kindly added a list of notes of the greatest importance to me, for which I offer him my hearty thanks.