Narrative of a battle at the bridge, with pulley studies
A prose account opening with Niccolo Piccinino's oration, paired with diagrams of ropes, wheels and weights
Two sheets are mounted together. The upper one carries a vivid prose narrative of a battle: a cast-list of Florentine captains, the opening oration of Niccolo Piccinino to soldiers and exiles, the Patriarch scouting the country from a hill, a vision of Saint Peter issuing from a cloud, and cavalry sent to check the onslaught. The lower sheet turns to mechanics, with rows of pulley-and-weight diagrams and notes explaining the four ways a rope-and-pulley can make a load hard to move and how the supporting rope bears double the weight it sustains.
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Opening of a battle narrative: Piccinino's oration
After naming the Florentine captains, the text directs that the action 'begin with the oration of Niccolo Piccinino to the soldiers and the Florentine exiles,' then show him mounting armed on horseback followed by forty squadrons of cavalry and two thousand foot. The Patriarch climbs a hill at dawn, sees Piccinino approaching from Borgo San Sepolcro in a great dust, prays with joined hands, and a cloud opens with Saint Peter speaking to him.
Four ways a rope-and-pulley resists motion
Drawing a weight with a rope running over a pulley can be made difficult in four ways: when the rope is not even, when the wheel is not round, when the hole receiving the axle is not round, or when the axle itself is not round. Each defect adds friction to the raising of the load.
A rope in a pulley system bears double its load
In a system of pulleys with weights, Leonardo notes that the length of the rope supporting the weight is, in every part, forced by a power double that of the weight it sustains, and the more so as motion is created and as that motion is faster. The numerals beside the wheels tally the multiplied purchase of the tackle.