Furnace has a melting section and {HEAD ~ a withdrawal section} bounded by {TAIL ~ side walls} of refractory material which extend to a glass outlet formed by an overflow edge remote from the melting section 
bounded by
Furnace has a melting section and { HEAD ~ a withdrawal section } bounded by { TAIL ~ side walls } of refractory material which extend to a glass outlet formed by an overflow edge remote from the melting section
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH