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