Key-operated grappling hooks, pivot motion and hammer percussion
Unequal motion of hooks about a pole, and whether a stiff or a bending handle strikes harder
The tong-like drawings at the top study how points move about a central pole: moving f toward c sends x toward t, and moving e toward b is impossible without breaking the pole. Turning a key draws the hooks d and f together, but their motions are unequal in force and speed because line a c is shorter than line b a, becoming equal only when the key's point comes below at r. Lower on the page Leonardo asks whether, of two hammers of equal weight, the one with a stiff handle or the one with a handle so thin it bends gives the greater percussion, and captions treat the fastening of the trunnions of short cannons and the seating of a wheel's cord.
On this page
Motion of points about a fixed pole
Moving from the centre downward, as f toward c, drives x toward t; moving d toward a drives x toward r, so moving d and f equals moving a c. To move e toward b would be impossible without breaking the pole, because moving e is as much as moving b, which is the pole itself. It is a study of leverage about a pivot.
Key-drawn grappling hooks with unequal motion
Turning the key downward brings the hooks d f together, but their motions are unequal in force and speed because line a c is much shorter than line b a. By the fifth proposition of the sixth, a b moves its hook more and with more effort, while a c does the opposite. Only when the key's point comes below at r are the motions of the hooks equalized in motion and power.
Does a stiff or a bending handle strike harder?
Two hammers of equal weight and shape are swung by the same power from handles of equal length. One has a thick, rigid handle; the other a handle so thin that it bends during the motion. Leonardo asks which of them delivers the greater percussion.
Fastening the trunnions of short cannons
A caption labels the fastening of the trunnions of the cortaldi, a type of short cannon. A neighboring line notes a way of seating the cord of a wheel. These brief headings tie the pivot studies to gun and machine mountings.