CONTINUOUS HEATING FURNACES 139 hottest portion of the chamber where complete combustion can take place before the gases cool below their ignition temperature. FIG. 116. The hot gases drop down toward the ingots or billets and lose their heat by coming in contact with them, and the colder gases then descend fur- ther to the lower level from which they flow to the chimney port. Compare this type of construc- tion with the working system of many contin- uous heating fur- naces of widely known and used designs. Fig. 116 is a photographic demonstration of the circulation of the hot gases (colored kerosene) in a Morgan continuous heat- ing furnace. Fig. 117 is a similar demonstration of the pocket FIG. 117.