STATIONARY ENGINES.

231

or three, as the inner pair, outer pair, or both pairs are thrown outof gear. The sewage is discharged into a wrought-iron trough,

~f £ “

1

Fig. 146.—Pumping Engines at Crossness. One-half Side Elevation.

through hinged leather-faced valves, which are suspended fromwrought-iron shackles, and fitted with wrought-iron back and frontplates. Each valve is 12 inches by 18. As has been before stated,substances which might prevent the proper action of the valves are