Double Bellows with Non-Return Valves
A twin bellows and the flap-valves that keep fire from entering it
The sheet, whose main figure is noted as drawn upside down, shows a double bellows together with a detailed study of its internal flap-valves. A caption explains that when bellows S blows, valve o p opens to drive air through hole n, while valve m c closes hole b, so that the fire cannot pass back into the bellows. The parts are keyed with the letters S, t, n, o, m, c, p.
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Double bellows and its flap-valves (S, o p, m c)
The lower figure is the double bellows; the upper detail shows its internal valves. When bellows S blows, valve o p opens and the air passes through hole n, while valve m c shuts hole b so that the fire cannot be drawn back into the bellows.