These notebooks?originally loose papers of different types and sizes?were largely entrusted to Leonardo's pupil and heir Francesco Melzi after the master's death.[125] These were to be published, a task of overwhelming difficulty because of its scope and Leonardo's idiosyncratic writing.[126] Some of Leonardo's drawings were copied by an anonymous Milanese artist for a planned treatise on art c.?1570.[127] After Melzi's death in 1570, the collection passed to his son, the lawyer Orazio, who initially took little interest in the journals.[125] In 1587, a Melzi household tutor named Lelio Gavardi took 13 of the manuscripts to Pisa; there, the architect Giovanni Magenta reproached Gavardi for having taken the manuscripts illicitly and returned them to Orazio. Having many more such works in his possession, Orazio gifted the volumes to Magenta. News spread of these lost works of Leonardo's, and Orazio retrieved seven of the 13 manuscripts, which he then gave to Pompeo Leoni for publication in two volumes; one of these was the Codex Atlanticus. The other six works had been distributed to a few others.[128] After Orazio's death, his heirs sold the rest of Leonardo's possessions, and thus began their dispersal.[129]

Some works have found their way into major collections such as the Royal Library at Windsor Castle, the Louvre, the Biblioteca Nacional de Espana, the Victoria and Albert Museum, the Biblioteca Ambrosiana in Milan, which holds the 12-volume Codex Atlanticus, and the British Library in London, which has put a selection from the Codex Arundel (BL Arundel MS 263) online.[130] Works have also been at Holkham Hall, the Metropolitan Museum of Art, and in the private hands of John Nicholas Brown I and Robert Lehman.[125] The Codex Leicester is the only privately owned major scientific work of Leonardo; it is owned by Bill Gates and displayed once a year in different cities around the world.

Most of Leonardo's writings are in mirror-image cursive.[

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