{TAIL ~ second mounting means} disposed on said trap for alternately mounting said trap on {HEAD ~ a horizontal wall} of said furnace 
{ TAIL ~ second mounting means } disposed on said trap for alternately mounting said trap on { HEAD ~ a horizontal wall } of said furnace
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH