WATER METERS 



729 



time the outlet 0, from the first compartment, which is on the 

 opposite side of the drum to S, is brought by the rotation below 

 the water level in the compartment, and discharges the water into the 

 trough T in which the drum rotates, and from which it flows away to 

 the discharge pipe. The height of the trough may be adjusted as 

 required, and as the volume discharged per revolution depends on the 

 depth of the immersion of the drum, this enables the discharge per 

 revolution to be adjusted. The number of revolutions of the drum, and 

 hence the volume passing the meter, may then be recorded on a suitably 

 engraved dial. 



When used for domestic supply purposes, discharge takes place into a 

 cistern from which the water is led over the building. An inlet valve on 





FIG. 350A. 



the supply pipe not shown in the sketch is then opened by a ball valve 

 when the water level in this cistern is lowered. 



Another meter of this general type is shown in Fig. 350A. The appara- 

 tus consists of two tanks of equal size carried on knife edges at B. Each 

 tank is fitted at one end with a syphon pipe C, and at the other with a 

 weight D. The liquid to be measured flows through the inlet pipe E 

 along the movable guide channel F into whichever tank happens to be 

 in operation. 



The weights D are so adjusted that until the tanks are full up to the 

 height marked G, they remain in a horizontal position, but as the weight 

 of liquid increases by the continued flow, the tanks come into the position 

 shown by the dotted line, when the liquid flows through the syphon pipe. 

 After the syphon has been started and the level of the liquid in the tank 

 has fallen sufficiently, the tank tilts back again to its original position, by 



