A single acting pump does its work through one end of the cylinder or barrel of the pump.
In double acting pumps the motion of the piston in one direction causes an inflow of water, and a discharge at the same time, in the other; and on the return stroke this action is renewed as the discharge end alternately becomes the suction end; the pump is thus double acting.
Finally pumps may be classified with reference to particular uses to which they are specifically adapted by their form and the materials they are required to handle.
Pumps now raise, convey and deliver beer, molasses, acids, oils, and melted asphalt. They also handle such gases as air, ammonia, lighting gas and even oxygen.
In the orderly progress of the contents of the volume, it will be seen that the main subject, occupying many pages with illustrations, is that relating to “Steam pumps;” those having a steam-end and a water-end and which consist of pump and steam-motor combined. An interesting class under Vacuum-pumps will be found, 1, the combined vacuum and feed; 2, the combined vacuum and circulating and, 3, the combined vacuum and refrigerating pumps.
Under Pumping Engines and the Steam Fire Engine will be found a description of the most brilliant and fascinating of modern scientific and mechanical achievements; these two sections relate to hydraulic engineering in its highest development.
HAND PUMPS.
The theoretical action of a pump has already been described and illustrated;—the practical operation is described in the note below. The subject is important enough to justify the space it takes to present these two descriptions of the action of a pump.
