Studies of ropes, knots and timber joints under strain
How cords wear and loops tighten, and how nailed versus lashed beam-joints hold
The verso gathers studies of ropes and timber joints and the forces on them. Notes observe that when one cord moves against a still one the still cord wears more, that two cords touching in motion wear each other, and that loops always cut the cord, especially where the bend is sharp, while the more the ends of a loop are pulled the tighter it grips. Further notes treat carpentry: trestles nailed at the front pull free through the leverage of their length, a bolt (chiavarda) should back up the lashings like a buckle's tongue, and a beam-joint whose angle is opened grows weaker when nailed but stronger when first bound with cord. The drawings show knotted and bent cords, cord wound round a stick, two lashed sticks and a bolt, several lettered a, b, c and so on.
On this page
Wear of ropes rubbing in motion
When one cord moves and the other stays still, the still cord wears away more than the moving one. The motions of two cords that touch one another are the cause of their wearing away.
Loops cut cords and grip harder when pulled
The loops always cut the cords, most of all where their angles or bends are of great curvature. And the more the ends of the cord making a loop pull, the more it tightens the thing surrounded by that loop.
Leverage loosens nailed trestles
All the fronts of trestles fixed with nails are easy to separate from their feet, because of the leverage that their length produces, with the counter-lever fixed upon their nailing.
Bolts should back up the lashings
Bolts (chiavarde) should be there in addition to the lashings, like the tongues to the buckles.
Nailed versus corded beam-joints
The more the angle of a beam-joint is opened beyond its first arrangement, the weaker it becomes when fixed with nails; but when the joint is first bound with cord, opening the angle instead strengthens it.