It was formerly customary to run the shell practically vertical to the top, putting brackets in the inside to support the hopper ring and other brackets on the outside to carry the wheelway for the filling barrows.

In early days the hopper ring was not even bolted down to the brackets, but with the greater frequence of violent slips which followed immediately upon the introduction of large percentages of fine ore into the burden, it was soon found necessary to have a more substantial construction. This was begun by making the brackets of steel instead of cast iron and bolting the hopper and hopper ring to them. Finally Mr. Julian Kennedy pointed out the general weakness of this construction and the necessity of holding the top of the furnace down until the violence of the slip had passed by. In fact he claimed that by preventing the sudden release of pressure at the top the violence of the slips could be much diminished, and he was the first to introduce the coned top shown in Fig. 163 in which the shell is drawn in to support the hopper ring directly, thus making a much better and tighter joint between the hopper and the shell and giving a construction of sufficient strength to resist all ordinary slips and explosions.

The great mass of brickwork formerly put in above the bottom of the hopper is in fact perfectly worthless as it has no heat-resisting functions to perform and only serves to make a joint between the hopper and the furnace shell, and generally a very poor joint it was, having to be supplemented by clay packing, and accompanied by more or less leakage of gas, particularly during the blowing-in periods of the furnace when the gas is most deadly. The elimination of this construction has also resulted in putting the gas outlets further up toward the top of the furnace where they belong, somewhat as shown in Fig. 170, which is an elevation of the furnace shown in Fig. 163 and shows the location of the gas outlets more clearly.

The wheelway of the hand-filled furnace is of course entirely eliminated as such, in modern mechanically-filled furnaces, but an operating platform is provided, generally about as shown in Fig. 163.