idly to the left, the ball was drawn in between it and the scroll, the teeth on each preventing its slipping; and, as it was carried around by the movement of the drum, the constantly narrowing space caused the ball to be subjected to great pressure, which expelled the liquid cinder and at the same time forced the ball Fig. 28.—Plan of the Rotary Squeezer. to assume before it was ejected from the machine the form of a cylindrical bloom. In order that the squeezer should accommodate balls of considerable variation in weight, and at the same time exert a powerful end-pressure or "upsetting" during the operation of shingling, a very heavy ring of cast iron (shown in the plane A B, Fig. 27) was made to rest upon the upper end of the mass of metal as it passed through the machine; this ring was kept in position horizontally and guided in its movement vertically by the upper part of the spindle of the drum b. The finished "bloom" was discharged from the "squeezer" at the right-hand side of the opening in the "scroll" through which the "ball" originally entered, and such was the rapidity of the operation that the "bloom" retained sufficient heat at its close to permit of its being passed directly through the "rolls" and rolled into "billets" or "muck-bars" without reheating.
The modern form of the above-described machine differs somewhat from that shown in the illustrations in the arrangement of its driving-gear, but the general principles embodied in the original construction are still retained. Large numbers of Burden Rotary Squeezers "are in use in the rolling-mills of the world, and it may fairly take rank as one of the most important improvements in the manufacture, of iron that have had their origin in America.
Coincident with the improvements in apparatus and methods for producing wrought iron, the general advancement of all the arts, and especially those relating to the manufacture of machinery, created a demand for forgings of a size impossible of execution by the ancient trip and helve hammers; and as a means of supplying this need for uncommonly heavy forgings, the