Page:Popular Science Monthly Volume 40.djvu/48

38 three inches thick and 115 inches wide, or sheets of an inch thick and 117 inches wide, and of course any intermediate dimensions of any length, and of a weight not exceeding six tons. This mill can turn out five thousand net tons per month.

Fig. 70 is a view of the hydraulic shears in the "slabbing-mill" of the Homestead Steel Works.

The men in the picture will assist the mind of the reader in forming a correct idea of the magnitude of this ponderous piece of mechanism, whose purpose is to cut into the required lengths the "slabs" as they come from the "slabbing rolls." The lower knife is stationary, and the movement of the upper knife in a vertical plane is insured by guides on the "housings" of the machine. The upper knife is actuated by a water pressure of about three thousand tons, and the shears are capable of cutting a section 24" X 48" of hot metal. The "slabs" are taken to the plate-mill, reheated, and rolled to the required dimensions. The above description of some of the machinery in use m the Illinois Steel Works and in the Homestead Steel Works must serve for illustrating the ponderous character of the mechanism of a modern "steel plant," as it is plainly impossible m this paper to speak of details which would require a volume to adequately

The "Bessemer process," as for many years conducted, could only deal successfully with iron which contained a very small quantity of phosphorus; this being the case, a very large proportion of the world's make of that metal was useless for the manufacture of steel; and therefore it was evident that any improvement by which such iron could be made available would have great value. This fact stimulated inventors to endeavor to