Water, air and fire forced through tubes by wind
Why driven matter divides on impact, unlike a ball that falls back down its own path
The top of the sheet shows a row of tubes (canne) labelled with eight experiments in which water, air, or fire is driven through a tube by the force of wind, together with a blowpipe shooting a ball and a rocket cast upward. In the text below, Leonardo argues that matter driven into a contrary element does not retrace its path on returning, because the more resistant medium divides the weaker driving force and shatters it, as a bombard's ball is broken against a fortress wall, whereas a ball shot straight up in still air falls back into the very hole it left. He ends with the demonstration of a lighted torch at a blowpipe's mouth, whose flame narrows to a sharp point when air is drawn through. A short heading above the lower paragraphs is visible on the sheet but is not part of the transcription.
On this page
Eight tubes driving water, air and fire by wind
A row of tubes at the head of the page is labelled with eight cases: water or air driven up a tube by wind, water falling down a tube, a ball shot from a blowpipe, fire drawn or driven through a tube, fire forced downward, and a rocket cast through the air 'by force of multiplication'. Each drawn tube corresponds to one caption.
Water and air exchanged between their elements through a tube
Several of the captions concern water and air moving through a tube: water driven up into the air by wind, water falling from high to low, and air driven down into the water by a tube and the force of wind. These are the water-and-air members of the eight-tube series.
Driven matter divides on impact; a ball returns to its own hole
Leonardo reasons that air or water driven perpendicularly up a tube by wind will not keep the line of its first motion on returning to its element, because the resistance of the penetrated medium overcomes the weaker driving force and divides it, so that it falls back in minute parts. A ball shot straight up in still air, by contrast, cannot be divided by the air and so falls back into the very hole from which it departed.
The bombard ball against living-stone walls as a model of percussion
The scattering of driven matter is likened to the ball cast by a bombard or mortar against the walls of resisting fortresses of living stone, which breaks apart and falls back equally in minute pieces. The comparison serves the physics of percussion rather than a siege design.