{HEAD ~ a lid} closing {TAIL ~ the outlet} of the outer chamber when the inner chamber is in the first position 
closing
{ HEAD ~ a lid } closing { TAIL ~ the outlet } of the outer chamber when the inner chamber is in the first position
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH