The notebook is written in Leonardo’s distinctive “mirror writing” possibly to preserve his secrets, possibly just because he was left-handed. The eBookTreasures version contains a tool to flip this writing back through 180 degrees.
The collection of notes were bought by Thomas Howard, 2nd Earl of Arundel in the 17th century, were bound and became known as Codex Arundel. The codex then passed to the Royal Society before coming to rest around 1831 in the British Museum Library, now known as the British Library.
These iBooks contain the complete manuscript or selected highlights along with text and audio commentary and the ability to reverse Leonardo’s mirror writing.