80 SMALL WATER SUPPLIES. 



case a pump larger in size than is absolutely neces- 

 sary, and working at a consequent lower rate of 

 speed, is in all cases an advantage. 



For the purpose of description a vertical treble 

 ram pump has been chosen, as made by Messrs. 

 Frank Pearn Co., because it is typical of the class 

 of engine, and a single or double ram pump has the 

 same essential features. It is illustrated in figs. 62, 

 63 and 64, while a horizontal pump is shown in figs. 

 65 and 66, designed for an electric drive. The pump 

 barrels are of close-grained cast iron, together with 

 the valve chambers, and vacuum vessels are formed 

 in one having a trough which collects leakage from 

 the glands. The valves and seats are of gun-metal, 

 and the type shown in fig. 60. The rams are of the 

 trunk type in small sizes of gun-metal, and large 

 sizes cast iron lined with gun-metal. They work 

 through neck rings and cast-iron glands packed with 

 hemp soaked in tallow. The crank shaft is of forged 

 steel, and works in gun-metal bushes of the usual type. 

 The connecting rods are of forged steel likewise ; 

 the air vessel is of cast iron. This class of pump is 

 also commonly known as a three-throw pump. In 

 order to give the reader a better idea of this class of 

 machine, a similar type is shown in fig. 67, taken 

 from a photograph. This class of pump may be 

 driven in a variety of ways, discussed later on, but 

 it must run slowly, and that is the reason of the 

 pulleys, gearing, and counter shaft shown. There is 

 now on the market a very good pump which has 

 been designed to run at high speeds, and so avoid 

 the wear, tear and noise of gearing and the necessity 

 of belts, etc. It is made by Messrs. Daniells & Co., 



