Recto: Studies of ribs and the diaphragm. Verso: Studies of architecture and a bird's wing

Recto: a drawing of ribs; a diagram of levels of the diaphragm in respiration with a note on its action. Verso: a note on hydrostatics; an elevation of a fountain; a ground-plan of two courtyards; a study of a bird's wing; slight architectural studies; a pulley, with notes on its action; two architectural elevations; notes on water and the earth. Around 1512 Leonardo spent much time at the family villa of his pupil Francesco Melzi at Vaprio d’Adda, outside Milan. The architectural studies on the verso of this sheet, including two drawings of an ornate wellhead, are probably plans for improvements to the villa. Leonardo continued his anatomical investigations while at Villa Melzi, working mainly with oxen and dogs as his subjects, and here he studies the bones of a bird’s wing. For many years Leonardo had been thinking about how to construct a flying machine, but he had little understanding of aerodynamic lift, and most of his designs involved a man operating huge flapping wings. At lower left he reduces the bird’s wing to a simple arrangement of hinged rods, possibly wishing to emulate the mechanics of the wing in his flying machine. Text adapted from Leonardo da Vinci: A life in drawing, London, 2018