The Blow, Pulleys, and Jets of Wine and Water
Mechanics of the blow with hydraulic tests of wine and water jets, and a star-shaped aperture
This folio interleaves Leonardo's mechanics of the blow with hydraulic experiments. Under repeated headings of "Blow," "Weight and force," and "Perspective," he asserts that a hammer-blow severs an iron where steady weight never could, that the blow outruns any motion already present in the struck body, and that a hanging weight pulls a pair of pulleys off their perpendicular. Two water studies close the page: gauging how much wine remains in a vat from the reach of its jet, and a proposed apparatus of a water-skin fitted with many equal spouts to derive a rule for the arcs of falling streams. A star-shaped aperture is offered for casting patterned sunlight.
On this page
The blow cuts an iron where weight and force cannot
The blow will cut the iron placed on the anvil at the point a, whereas weight or force would never do it.
A hanging weight draws the pulleys off their perpendicular
The weight c-d makes the little wheels a-b leave their perpendicular line and rise, drawing close to the beam that supports them, so that the line b-n falls at equal angles upon the angle a-b-d.
The blow outruns motion already in the struck body
Because the blow is swifter than motion, the thing touched by the blow, though it is in motion, obeys the effect of the blow before it obeys the caused increase of its motion.
Sunlight through a star-shaped aperture
If you make the sun's rays pass through the star-shaped aperture, you will see beautiful effects of perspective in the impact made by the sun that has passed through.
Gauging the wine drawn from a vat by its jet
One can tell how much wine has been drawn from a vessel, knowing only its diameter. Catch the jet where its curve straightens: receive a at n, then b at m, and set the plumb-line f where the inner wine borders the vessel; as much as a-o enters into o-p, so much f-n enters into f-m, if the holes and wood are equal.
A water-skin with many equal spouts to test jet arcs
To make a rule for these motions, use a bag full of water with many spouts of equal bore set in a line. As much as c rises higher than d, so much the middle of the arc d is found farther beneath its perpendicular at h; the spouts should rise on a level plane, be of equal length, then be bent to different positions.