Fig. 13.—Savery’s Engine, a. d. 1702.
L is the boiler in which steam is raised, and through the pipes O O it is alternately let into the vessels P P.
Suppose it to pass into the left-hand vessel first. The valve M being closed, and R being opened, the water contained in P is driven out and up the pipe S to the desired height, where it is discharged.
The valve R is then closed, and the valve in the pipe O; the valve M is next opened, and condensing water is turned upon the exterior of P by the cock Y, leading water from the cistern X. As the steam contained in P is condensed, forming a vacuum there, a fresh charge of water is driven by atmospheric pressure up the pipe T.
Meantime, steam from the boiler has been let into the right-hand vessel P, the cock W having been first closed, and R opened.
The charge of water is driven out through the lower pipe and the cock R, and up the pipe S as before, while the other vessel is refilling preparatory to acting in its turn.
The two vessels are thus alternately charged and discharged, as long as is necessary.
Savery’s method of supplying his boiler with water was at once simple and ingenious.