Near the top of each of the working chambers, A, A, and of the vacuum chamber, J, is a small tapped hole, into which is screwed a brass air check-valve, so that its check hangs downward. The air check-valves in the chambers, A, A, allow a small quantity of air to be automatically admitted above the water, and ahead of the steam, separating the steam and the water upon their first entrance, thus preventing condensation, and forming an air piston, which is always new and tight. The air check-valve in the chamber, J, likewise admits air automatically, which serves to cushion the ram action of water consequent upon the alternate filling of the chambers, A, A.
Fig. 557.
Fig. 558.
Fig. 559.
Fig. 560.
