One way valves in {TAIL ~ the bottom} of {HEAD ~ the dipper} allow water to pass into the dipper 
One way valves in { TAIL ~ the bottom } of { HEAD ~ the dipper } allow water to pass into the dipper
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH