CHAP, iiij PUMPS. 59 



it is therefore named the air-reservoir. The velocity with which the 

 water escapes from the hose depends on this pressure, and as this only 

 varies slightly if the air-reservoir is of sufficient capacity, it follows 

 that the discharge from the jet is nearly constant. 



A steam fire-engine consists of a steam-engine, pump, and boiler, 

 fixed to suitable framing, and mounted on wheels and springs. There 

 is a box to contain hose and implements, which also serves as a seat 

 for the firemen and driver. The whole machine is of the lightest 

 possible construction consistent with strength and durability, and is 

 readily drawn by a few men, or, for greater distances, by a pair of 

 horses. 



FIG. 41. Hand fire-engine with lever. 



Steam fire-engines comprise three classes : Land, Floating, and 

 Fixed. The appearance of the Land steam fire-engine is now familiar 

 to all the dwellers in our large towns, most of whom have seen it in 

 its rapid progress to a fire, drawn by horses, and carrying its com- 

 plement of firemen with hose and implements. 



Floating steam fire-engines are a desirable acquisition in ports and 

 docks, where warehouses and stores of goods are in proximity, to 

 water. They are made self-propelling, or are placed in a vessel to be 

 moved about by steam-tugs. 



Fixed steam fire-engines are placed in manufactories, or other 

 places where steam boilers are already in use, the steam from which 

 is available both day and night for working the engine. 



