RCIN 912688 and RCIN 912716 are fragments of a larger sheet depicting a water-clock, though the mechanism is obscure. The body of the clock is seen in plan at lower left, a cluster of 24 tubes of uniform height and increasing diameter, to be filled by a steady flow of water such that after one hour the first would be full, after two hours the second would also be full, and so on. At top right (RCIN 912716) a figure is striking a large bell mounted over the device, though it is not apparent whether he is a living being who would simply observe how many tubes were full, or some sort of automaton. Two alternative and technically simpler designs at lower right (RCIN 912716) consider dividing the body of the clock into 300 equal chambers (the sum of the numbers 1 to 24). Leonardo had mentioned water-powered musical devices in his plans for the garden of Charles d’Amboise (RCIN 912591), an erudite reference to the amusements of antiquity described by Heron of Alexandria (see RCIN 912690, 912691), and it is quite possible that these designs were for the same project.

Text adapted from Leonardo da Vinci: A life in drawing, London, 2018