Machine for Hauling a Tree Trunk from the Water
A rope-and-lever rig with a pawl to raise a submerged trunk onto the bank
Leonardo designs a rig to pull a tree trunk out of the water quickly and easily: ropes are fastened at each end of the trunk and led to a man's hands, while a central lever f g grips the trunk and rolls it up onto the bank m L. A detail shows a pawl (a e b) that keeps the raised load from slipping back. The apparatus is drawn as roller-and-lever assemblies at the upper and middle right; a closing note poses an unrelated optical question about whether a cloud or an equal thickness of water darkens the earth more.
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Rope-and-lever rig to draw a tree from the water
K h is the given tree; a rope fastened at b takes hold of the trunk at n and returns to the man's hands at c, and the like is done from the opposite face. At the same time the lever f g grips the trunk in the middle, and as c pulls, e f is lowered, so the tree climbs onto the bank m L by turning on the lever.
Pawl to keep the raised load from slipping back
In the detail, a e b perform the office of a pawl so that the raised column cannot return backward. The device locks each increment of the heavy lift in place.
Cloud or water: which darkens the earth more?
A closing question asks which would darken the earth more: a large dark cloud interposed between the earth and the sun, or a quantity of water of thickness equal to that cloud, the cloud touching the ground just as the water touches it.