River waves against the wind; surface and bottom currents
Why river waves rise higher against the wind, plus a note that ten small blows are weaker than one great blow
Notes and diagrams on how river water behaves when the wind blows against the current: the waves rise higher, the surface flow is checked, and the doubled bottom current scours the channel. A marginal figure distinguishes surface water (a) from bottom water (b), and a perspective section shows water spreading where the ground is less level. A separate opening note observes that ten one-pound blows do not equal a single ten-pound blow.
On this page
Ten small blows are weaker than one great blow
Ten blows of one pound each add up to ten pounds of blow, yet together they do not deliver as much impact as a single blow of ten pounds. The note isolates the difference between accumulated small impulses and one concentrated percussion.
Waves rise higher where a river runs against the wind
River waves running against the wind's course stand higher than others because the wind drives back the surface. The checked surface water finally falls beneath the rest and sinks, joining the bottom current, which must therefore double or the river would overtop its banks.
Surface water (a) and bottom water (b)
A labelled wave figure marks a as the water of the surface and b as the water running along the bottom. An obstacle set on the bank at mid-height of the current is said to be the ruin of the middle of the opposite bank.
Water spreads where the slope is less straight
A perspective section of undulating, descending ground shows water crossing surfaces of varying level. Where the path is less straight, the water spreads out more widely.