Leatherless water-driven bellows, in four parts
A rotating bellows without leather, worked by water and air, turned by a man on its stairs or by falling water
The page works out in detail a bellows without leather, drawn in four separate parts and again complete. It is kept half full of water (M N); as it turns, N rises to meet a vent S T, and water flowing from N to M forces an equal volume of air out to make the blast. A detail shows the vent o held open by a spring n and shut again by the opposite base. Leonardo advises building it of oak coated inside with turpentine and pitch, filling it with salt water so it does not spoil, and turning it by the counterweight of a man walking up its stairs, or by falling water.
On this page
Bellows drawn in four parts, with labels
The bellows is shown taken apart into four pieces, with lead weights (piombo), the marked casks R F and M N, and the pivot on which it turns on the pipe. Lengthening the passage of water from one cask into the other, to equal the bellows, makes it blow much harder.
Vent o held open by spring n
A detail of the valve: the vent o carries a spring n that keeps it open, and once the channel S T has passed, the opposite base forces it to stay shut.
How water displaces air to make the blast
The lower half stays full of water, M N; in the continuous turning, N rises to the vent S T in the outer casing and meets the hole o of cask N. As water passes from N to M, an equal volume of air enters at o and an equal volume leaves cask M, and the air driven from M by the water is what makes the bellows blow.
Materials, sealing, and drive
It should be made of oak to resist the water over time and coated inside with turpentine and pitch so the upper, dry part does not open when idle. The fixed base below channel S T stays still while the rest turns within it like a box in its lid. Fill with salt water so it does not corrupt; it may be driven by a man walking up its stairs or, usefully, by falling water.