at this critical period of the process that the person in charge of the operation judges of the proper time to "turn down" the "vessel" and cut off the blast. When that time arrives, the vessel is turned with its body in a horizontal position, and a certain weight of a metal called spiegeleisen is added in a molten state, and the converter is then turned still farther down into the position shown in Fig. 58, and its contents poured into a casting ladle H, attached to the end of the arm of a crane, G. This ladle is provided with a, "tap-hole" in its bottom, which can be closed by a valve attached to the lower end of the spindle L (Fig. 59). Of course, the interior of the ladle as well as the valve and its spindle are made of the best fire-resisting material obtainable. The spindle L is raised or lowered to open or close the "tap-hole" by means of a lever, N (Fig. 58), which operates a vertical slide-bar to the upper end of which the spindle L is attached. The crane-arm G is attached to the upper end of a cylindrical ram or post capable of moving upward as well as rotating in a hydraulic cylinder, E. The ingot molds (of which one is shown at K) are placed in a circle, whose center is that of the cylinder E, and are filled in succession by swinging the crane about the same center. The molds K are made of cast iron, and are smaller at the top than at the bottom, in order that they may be readily "stripped" off the ingots of steel.
The apparatus shown in the above-described figures was the invention of Henry (now Sir Henry) Bessemer. It is remarkable for its ingenuity and perfect adaptation to the needs of the new process, and, notwithstanding the lapse of over thirty years and the accumulated experience of multitudes of metallurgists and engineers, substantially the same apparatus is to-day in use in every Bessemer steel-works in the world. Of course, there have been many changes and some improvements in details, but its essential features remain as they were planned by their inventor thirty-six years ago—the converters still turn on their trunnions and receive their air-blast as has been described; the casting-ladle continues to be attached to a hydraulic crane and to discharge its contents through a valve-closed "tap-hole" in its bottom; hydraulic cranes are still used to rapidly handle ingots and molds; and these foundation facts of ingenious design promise to continue in use for all time as enduring evidences of great originality in the selection and adaptation of means to ends, and fairly entitle their inventor to a foremost place among the mechanicians of the century.
[To be continued.]
