A great hinged valve and water-bellows with cloth flaps
Flap-valves regulating flow through a pipe, doubled and single cloth, and bellows kept on salt water
The page details a large valve apparatus: a rounded chamber fitted with a bank of hinged flap-valves (uscioli) opening into a wide pipe, drawn with a tall duct at the left and bellows figures below. Notes on either side state that the flow is more abundant the less the little doors descend, and that the total opening of the doors is made equal to the width of the pipe. A detail shows the cloth (tela) of the valve doubled between n m and single between c b, warning that the doubled cloth must not rub against itself; a further caption describes bellows kept on salt water so they do not rot.
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Flap-valves sized to the width of the pipe
The flow will be more abundant the less descent the little doors have, and the whole space of the little doors is made equal to the whole width of the pipe. The rounded chamber carries a bank of hinged flaps opening into the wide duct.
Doubled and single cloth of the valve
Between n m the cloth a is always double, and between c b it is single; care must be taken that where it is double the two layers do not rub one against the other, but stay as close together as possible.
Bellows kept on salt water
The figures of water-bellows carry the note that the bellows are kept upon salt water so that they do not become corrupt or rot.