The hot water in {HEAD ~ the tank} is maintained at a constant level so that the quantity of water discharged by {TAIL ~ the dipper} is fixed 
The hot water in { HEAD ~ the tank } is maintained at a constant level so that the quantity of water discharged by { TAIL ~ the dipper } is fixed
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH