Brunelleschi demonstrates his 3-speed reversible ox-driven hoist

Among the machines that Brunelleschi invented to achieve his architectural vision for the dome was a 3-speed, reversible, ox-driven hoist. We know about this ingenious machine because a young Leonardo da Vinci made a sketch of it decades later as it stood abandoned in the work yard next to the cathedral. Credits: Many thanks to Professor Mark Cutkosky (Brunelleschi) and the Stanford team of students who built the scale model.