The manuscript by Leonardo da Vinci, of which a complete English translation is here offered (so far as the writer is aware, for the first time), is known as the " Codice sul Volo degli Uccelli e Varie Altre Materie " (Codex on the flight of birds and other matters). It is a small note-book of some 30 pages, and measures about 8.4 inches by 6 inches. It was written at Florence in the year 1505, between March 14th* and April 15th. f A close study of this manuscript has been made by G. Piumati+ in a very fine edition containing an excellent facsimile of the original note-book, together with (a) a printed copy folio by folio of the old „ Italian script in which it was written, (b) a rendering into modern Italian, and (c) a French translation by C. Ravaisson-Mollien.