There are a few quite important features not found in pumps of usual construction. The pumps are composition fitted throughout, the water cylinder bushings and plungers and linings to stuffing-boxes are of composition, the piston and valve rods, made unusually heavy, are of Tobin bronze. The mixture of the copper and tin composing the plungers and bushings varies for the two so as to prevent their cutting. Owing to the very high speed at which these pumps are liable to be run during a fire, all the working parts are made excessively strong, and the valve area and water passages are larger than usual. The interior of each Underwriter pump is treated with a rust-proof coating, and every precaution taken so that the pump will start instantly after an indefinite period of disuse. Figs. 307 and 308 exhibit two somewhat varying but acceptable forms of the duplex steam pump. _Among the attachments included in an outfit_ for the underwriter pump may be mentioned: an elbow or tee for the suction connection with a large suction air chamber, a set of brass priming pipes with special gate and check valves for the same, an automatic water pressure relief valve fitted to a cone and overflow pipe, a steam gauge and a special water gauge with duplex spring, each of which in the Underwriter Pump is mounted on an ornamental plate rigidly attached to the machine. [Illustration: FIG. 308.] Straightway hose valves for the proper number of streams are placed in the neck to a very large discharge chamber, and there is also a large discharge opening for connection to the system of hydrants and sprinklers. A stroke pointer is attached which travels between graduations marked on the yoke, indicating the length of stroke which pump travels, a one-point sight feed cylinder lubricator, a capacity plate with enamelled face giving instructions for operating, etc., is attached to each machine. SPECIFICATIONS OF THE National Board of Fire Underwriters FOR THE MANUFACTURE OF STEAM FIRE PUMPS AS RECOMMENDED BY THE National Fire Protection Association. EDITION OF 1904 THE NATIONAL STANDARD PUMP. This pump is merely a pump of the well-known “duplex” type, built in a very substantial manner, and with certain improvements suggested by the experience of inspectors with Fire Pumps. The principal points of difference between the National Standard Pump and the ordinary commercial pump are: _1st. Its steam ports and water passages and air_ chamber are made much larger than in common trade pumps, so that a larger volume of water can be delivered in an emergency without water hammer. _2nd. It is “rust proofed” that it may start instantly_ after disuse, by making its piston rods and valve rods of Tobin Bronze, instead of steel; its water pistons, stuffing boxes and rock-shaft bearings of brass, instead of cast iron. Its valve levers are made of steel or wrought-iron forgings, or of steel castings.