The Codex Arundel:

On the left-hand page are notes, mainly on the physical behaviour of boiling water, interspersed with sketches of machinery and diagrams. On the right-hand page are notes on the landscaping effects of rivers flowing down mountain peaks, illustrated with pen sketches.

This notebook is not a bound volume used by Leonardo, but was put together after his death from loose papers of various types and sizes. The first section was begun at Florance on 22 March 1508, but the remainder comes from different periods in Leonardo’s Life (1452-1519). Most of these notes, and many others found in different manuscripts, are the raw materials for a book which Leonardo hoped to write on the physical properties and geographical effect of water. They are written in the Italian, and in Leonardo’s characteristic ‘mirror-writing’, left-handed and moving from right to left.

This manuscript was acquired in Italy by Thomas Howard, Ear of Arundel (1586-1646), the greatest English collector of art of his day. In 1681 it was presented to the Royal Society by Henry Howard (his grandson) and transferred to British Museum in 1831.