Water Spouting from Siphons of Different Nozzles
Three siphon tubes, and why a thin nozzle spouts as high as a thick one
Three water-filled siphons are drawn in a row across the top of the sheet: an inverted U with two equal openings at the same height, and two J-tubes whose lower spouts grow successively narrower. Leonardo argues that a siphon of uniform width, wetted along its whole height, will make water spout up to the same height whether it issues from a thin or a thick nozzle. His reason is that thin water is driven by a thin part of the column and thick water by a thick part, so the driving force is matched in each case.
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A thin nozzle spouts as high as a thick one
If the siphon has uniform width and is touched by water throughout its height, water issuing from the bottom and guided upward by the nozzle's lips will spout as high from a thin nozzle as from a thick one. The thin stream is driven by a thin part of the water column and the thick stream by a thick part, so each is driven equally.
Three siphons compared
Across the top of the page stand three water-filled siphons. The first is an inverted U with two equal openings at the same height; the second and third are J-tubes whose lower spouts grow successively narrower, yet throw water up to the same height.