Percussion and rebound: how a blow spends its impetus
Drums with axles of unequal poles, and measured bounce studies
The verso opens with a heading on 'deformity' and the difference of poles (axles) in one and the same body, illustrated by drums (78-81, 85) whose cylinders bear the ratio labels tripla, dupla and prima. Below, Leonardo analyses percussion: a blow struck between more unequal angles is weaker, and of two struck objects the one that bends less takes the greater harm while the first consumes most of the impetus. A quantified example holds that if the impetus is 4 and the first percussion consumes 1, the reflected percussion will be 3, alongside a note on measuring the second bounce upon the cord.
On this page
Drums with axle-poles of unequal diameter
A heading on 'deformity' and the difference of poles in one same body introduces a row of drums whose cylinders bear the proportional labels triple, double and first. They study how differing axle diameters change the mechanical behaviour of one shaft.
A blow between more unequal angles is the weaker
The blow caused between more unequal angles is of greater weakness, yet strikes with more power the object set against the rebound. Of two struck objects the one that bends less is harmed more, while the first consumes the greater part of the impetus so the second stays unharmed.
Impetus 4, first blow spends 1, rebound is 3
If the power of the impetus is 4 and the first percussion consumes one, the reflected percussion will be 3. Leonardo puts a number to the loss of impetus at each impact.
Measuring the second bounce upon the cord
A short caption proposes a test for measuring the second bounce from the first, taken upon the cord. It ties the percussion theory to a concrete measuring arrangement drawn nearby.