_Packing_—The stuffing boxes should be carefully packed and the gland brought up firmly against the packing; screwing up the gland by hand should be sufficient. Large sizes of suction and discharge pipe are desirable, because the friction of the water in the pipes thus reduced makes the pump work easier. POWER PUMPS POWER DRIVEN PUMPS. By _a power-driven pump_ is meant one actuated by Belt, Rope-transmission, Gear, Shafting, Electric-motor, Water-wheel, Friction, or by direct connection to a power shaft. It thus becomes very frequently a question which apparatus is most desirable. These are classified, thus— 1. Single power pumps, 2. Duplex power pumps, 3. Triplex (triple) power pumps, 4. Quadruplex, etc. Where the sizes still further increase they are named from the number of barrels or water cylinders, but when of much larger size than the Triplex they come under the classification of pumping engines. Where power can be had from a shaft in motion there is no pump so economical as the power or belt driven pump. This fact is shown by the rapid increase in the number of applications of this type of pump: the reduced cost of manufacture in making the teeth of the gear wheels, the use of automatic machinery, the production of interchangeable parts have tended to produce a high grade of machine at an attractive price. The energy expended in operating the power driven pump is obtained at the same economy as that required by the machinery in the mill or factory, and as a modern automatic cutoff engine will develop a horse power with considerable less steam than the direct acting steam pump the cost of the power required by the power driven pump is correspondingly less; it participates in the economy of the steam engine using from one and a half pounds of coal to five or six pounds per H. P. per hour. For this reason the power driven pump is oftentimes the more economical, and especially where shafting is adjacent to the location of the pump, or can be conveniently arranged by simply adding another length of shafting with the necessary pulleys, or even by cutting suitable openings through the walls for the belts. _Single, duplex and triplex power pumps_ are described and illustrated upon the succeeding pages; power pumps are built with one, two, three, four or five cylinders and for either high or low pressure or general service, and their sizes, capacities, and the materials they handle are no more numerous than their combinations in erection. The portion of this work devoted to power pumps should be especially interesting and instructive to the attendants operating steam, compressed air and power driven pumps. Particular attention has been given to _single-cylinder steam pumps_ because of the great variety of steam-actuated valves to be found in practice, each differing from the other in one or more essential features.