On Blow and Motion: percussion through air and water
Concussion that kills nearby animals, jerked versus continuous motion, and the sound of a blow
This text-only page extends Leonardo's science of percussion. He claims that a blow struck on a stone surrounded by air or water causes the death of the nearby animals, that grain packed by a blow occupies less space, and that a cord is harder to drag straight over the ground than when coiled. He then treats motion in jerks as greater than continuous motion, and explains how a dense suspended body struck by a dense blow fills the surrounding air with sound — deeper in tone the greater the volume of air around it.
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Percussion transmitted through water
A blow given to a stone surrounded by air or water is the cause that all the nearby animals die. Likewise a dense body struck by a powerful blow presses the surrounding air or water and kills the little animals enclosed against its surface.
Grain compacted by a blow; a coiled cord easier to pull
Grain placed in its receptacle occupies less space when struck by a blow. And far more difficulty is found in moving a cord drawn in a straight line over flat ground than one drawn when wound into a round form.
Jerked motion is greater than continuous motion
Motion that is overcome by resistance, if it proceeds in jerks, will be greater than continuous motion.
The sound made by a blow on a suspended body
The denser a suspended, freely movable body is, and the denser the body that strikes it, the more it fills the surrounding air with the sound of the blow; and the greater the volume of air around it, the deeper the voice with which it fills that air.