Springs on Mountain Peaks; Water Falling into a Channel
A polemic against the sea-origin of mountain springs, and the hollows made by falling water
The page opens with a sharp argument against the theory that the springs on high mountain peaks are fed by sea-water pushed up because the sea stands higher than the mountains, urging the theorist to go back and learn from nature. It then turns to a hydraulic observation: water falling into a channel as wide as the falling stream digs a deep hollow in the surface, while a broader basin is protected by return-eddies and a narrower one throws the water upward. A marginal note refers the scouring of a channel bed to a promised ninth book. A small pen sketch at the lower right shows water dropping into a channel.
On this page
Against the sea-origin of mountain springs
Leonardo challenges the claim that water rising to the high peaks comes from the sea, pushed up because the sea stands higher than the mountains. He asks why a single particle of water should be granted licence to climb so high and pierce the earth, while the rest of the water, bordering the yielding air, is not raised to the same height. He tells the theorist to return and learn from nature.
Concavities made by water falling into a channel
Water falling into a channel exactly as wide as the falling stream cuts a deep concavity in the water's surface. If the receiving width is greater, the return-eddies push the water back into the hollow so that little concavity forms. Water narrower than the stream that strikes it is instead thrown upward.
Scouring of the channel bed
A marginal note treats the water that clears away the bed where it plunges, acting with speed and with slowness according to the width, depth or narrowness of the place. Leonardo defers the fuller treatment to a promised ninth book.