I have had placed in my hands by B. B. Woodward, Esq., F.S.A., the Queen's Librarian, a Map of the World, which he has found in Her Majesty's Library at Windsor, in the collection of papers in the handwriting of Leonardo da Vinci. Mr. Woodward's object in sending it to me was that I might ascertain as nearly as possible the date of its construction, from the nature of the geographical information which it contained. It was evident at a glance that, apart from the value attaching to it from its connection with so illustrious a name as that of Leonardo da Vinci, the map possessed an intrinsic interest in connection with the history of geography and cartography, inasmuch as it not only belonged to a period fertile in geographical discoveries, though scantily represented by maps which have come to our knowledge, but contained delineations of a stage in those discoveries not represented at all in any map with which I am acquainted. Independently of this, it happens to possess some special points of priority of information, which have led me to think it desirable to submit it, with the following notice of its contents, to the attention of the Society of Antiquaries.