The Codex, which bears the mark 699 in Lord Leicester’s library, probably arrived there after being bought by Thomas Coke, later Lord Leicester, during one his stays in Italy during his youth. Born in 1697, he took possession of Holkham in 1707, and before he was twenty years old had already stayed many times in Rome, where he was (to recall the dates which are more certain) in February and March 1713, from March to June of 1714, from June to September of 1716, and from January to April of 1717. At that time he used to look for rare and antique things with the help of the sculptor and restorer Cavaceppi, who may have put him in touch with the owner of this Codex, Giuseppe Ghezzi; since one may suppose that this painter (the father of Pier Leone, famous for his caricatures), dying at a great age in 1721, sold him the manuscript directly. Ghezzi, modestly informed, it appears, on the contents of the Codex, but only vaguely aware of its value, busied himself to sell it, as appears from the boasting nature of the frontispiece to the Leicester manuscript and from some notes, written by an unknown hand (they could be by the same hand that wrote the frontispiece now mentioned) and contained in a notebook in the Milan State Archive. Here, Bonelli found them and published them in the year-book of the Vinci Collection , thus providing useful information on the history of the manuscript: “In the Life of Leonardo described by the French Raffaele Du Fresne it is said that the opportunity of the Naviglio della Martesana there provided the grounds for writing about the nature of the weight of and motion of water with various designs of wheels, and mills, and water machines to raise the water and regulate its flow”. “This book, hand-written backwards from right to left, in the fashion of Leonardo, has been found this year 1690 by Sr Giuseppe Ghezzi in a chest of manuscripts and drawings of Guglielmo della Porta, sculptor of the sepulchre of Paul III who as a youth, we know, was a pupil of Gio Tomaso della Porta, his uncle, who taught him to copy various studies of Leonardo da Vinci, which he must have had many of, giving them to his nephew to study, and it is no wonder that Gio Tomaso was a pupil of the sculptor known as the Hunchback of Milan, a contemporary of Leonardo”. “S.r Ghezzi has appropriate esteem of it and knows that its true home would be the Milan Library along with that on light and shade which Sr Lando intended to give to Sr Card. Federico Borromeo. The P. r. should be most pleased at such glory, but to purchase it and donate it, finds himself short of money to buy a study of water, so that it must wait until such money is made”. The information, found in this document, on how Ghezzi came to be in possession of the manuscript, is even more pertinent (despite the omissions and inexactitudes which it gives rise to) perhaps in the light of the facts that the prank by which a previous inscription on the frontispiece already mentioned was scraped