Three Ball-Launching Devices: Impetus, Collision, Percussion
Sketched troughs and supports with balls, illustrating how experience deceives the unwary
The right column carries perspective sketches of ball-launching devices, mounted troughs holding rows of balls on bracketed supports, with a note on how experiences deceive those ignorant of their natures, since things that seem alike are often greatly varied. The left column labels a detail a b c d e, each ball set in the middle of four triangles, and distinguishes three motors of different power and nature: the first works only by impetus, the second by collision, the third by percussion. Leonardo explains how the first varies across its breadth as each ball's driving power grows with the ball's weight, while the four balls thrust by powder will each go awry because of the triangles that box them in.
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How experience deceives the unwary
The right-column note warns how experiences deceive those who do not know their natures, because things that often appear one and the same are in fact of great variety, as the drawings here demonstrate. It introduces the comparison of three differently powered launching devices.
Three motors: impetus, collision, percussion
The detail marked a b c d e (each ball set in the middle of four triangles) shows three motors of differing power and nature: the first acts by impetus alone, the second by collision, the third by percussion. In the first, driving power grows with each ball's weight; in the second the power is equal against every opposing body; the four balls thrust by powder each go awry because of the triangles that box them in.
Perspective sketches of ball troughs on supports
The right margin holds sketches of open troughs holding rows of balls, one resting on a bracketed support with an arm swinging downward. These are the launching mechanisms the notes compare.