What wearable rescue device did Leonardo da Vinci design as a pyramid-shaped parachute?

Leonardo da Vinci designed a pyramidal parachute as a wearable rescue device. In a manuscript note, he described a linen canopy supported by a wooden frame and shaped like a pyramid, intended to let a person descend safely from a great height.

His proposal is associated with the Codex Atlanticus and is usually dated to around 1485. Leonardo estimated that a structure about 12 braccia wide and 12 braccia deep could support a person during a descent. The braccio was a historical Italian unit, so the exact modern conversion varies.

Leonardo did not demonstrate the parachute. In 2000, British adventurer Adrian Nichols constructed and tested a replica, reporting a successful descent, although he used a modern release method for safety. The design differs from a modern parachute, whose flexible canopy is normally packed and deployed after a jump.