Catapults, hoisting cranes and a bridge over deep water
Notes on a counterweight catapult, a composite beam, timber clamps and gear-driven lifting gear
The sheet is filled with engineering sketches: counterweight catapults, cranes and hoists with large toothed wheels and pinions, clamps for binding timbers, and men erecting a bridge. Leonardo notes that a catapult shoots in the direction from which its arm departs and that a counterweight should strike the ground rather than hang on the rope. A geared detail is labelled with 200 teeth, one braccio and 1200 pounds. A bridge is designed to span water too deep for supporting posts, so that it touches the banks with only its two ends, while composite beams are to be glued with pitch, bole and hot brick.
On this page
Firing direction of the catapult
For a catapult ready to fire, Leonardo notes that it shoots in the same direction from which its arm departs. The remark ties the launch of the projectile to the swing of the throwing arm.
The counterweight should strike the ground
On another catapult he instructs that the counterweight must not remain resting on the rope as it falls, but should strike the ground so that the rope is left slack. The note governs the release and the free travel of the falling weight.
Geared detail of the catapult
A detail names the wheel, pinion and counterweight, marked with 200 teeth, a notch, one braccio and 1200 pounds, with a part that stops the pulling. It specifies the gearing that spans and locks the machine.
Clamp gripping chained timbers
At the left a figure shows a stirrup or bracket that clamps together timbers chained end to end. It secures the joint of the composite members.
Composite beam glued with pitch and bole
A composite beam is to be glued together with pitch, bole and hot brick. The recipe joins shorter members into a single longer beam.
Bridge that touches only the two banks
Where the water is too deep for the supporting timbers to reach the bed, Leonardo makes a bridge that touches the banks with only its two extremities. Men are shown erecting it, with an instruction to bind it wide.