placed between them. The "gate" g, to which the upper knife is attached, has a vertical reciprocating motion communicated to it by means of the eccentrics e and the rods f, and, as the upper knife h has an inclined edge, the shearing will commence on the right and gradually extend to the left as the "gate" g descends. Shears of this description have been made to cut ten feet in length at one movement of the "gate" g. Such tools are very heavily geared, and are usually driven by a special steam-engine.
The first iron-works in the United States in which iron was puddled and rolled into bars was built by Colonel Isaac Meason, in 1816 and 1817, at Plumsock, on Redstone Creek, between Connellsville and Brownsville, in Fayette County, Pennsylvania. Swank tells us that "Thomas C. Lewis was the chief engineer in the erection of the mill, and George Lewis, his brother, was the turner and roller. They were Welshmen."
We have no exact description of the machinery of this mill, but we are told that, in addition to the rolls, "the mill contained two puddling-furnaces, one refinery, one heating furnace, and one tilt-hammer"; and that "the iron was refined by blast and then puddled." This mill produced "bars of all sizes, and hoops for cutting into nails." The mill was started on September 15, 1817,
Fig. 45.—Train of Rolls for Square and Flat Bar Iron (1817).
and continued in operation until 1824, when it was destroyed by a flood, and never rebuilt. Although we have no details of the roll train used in this mill, it is fair to assume that, as its designers were Welshmen, they followed as closely as possible the practice with which they were familiar. Fig. 45 is an elevation of a train of rolls such as was in common use in England and Wales at the beginning of this century for rolling square and flat bar
