Page:Popular Science Monthly Volume 38.djvu/174

162 briefly alluded to the fact that the earliest known method of obtaining iron from its ores produced a forgeable and weldable metal. We now purpose to describe more fully this primitive process, and to illustrate some of the machinery by which the iron produced was wrought into bars of various sizes and forms. The process illustrated by Fig. 1 (page 147) is with slight modifications still in use in Africa, and from iron produced in this rude way the native Kaffir blacksmiths forge the heads of such "assagais" or spears as were used with deadly effect in the last conflict of the Zulus with England.

The quantity of iron that can be obtained by this simple process as the result of a single operation is quite limited and only sufficient for the forging of implements of very moderate size; but, as mankind gradually improved the conditions of life, the necessity for larger masses of the most potential metallic factor of civilization became more and more urgent, and to meet this demand there was revealed to some receptive and executive intelligence among men the means by which such larger masses of iron could be obtained, and the "Catalan forge" or "blomary fire" supplied for a time the world's needs for an improved process of manufacturing wrought iron. A section of one of these "forges" or "blomary fires" is represented by Fig. 10. The cavity of the hearth d, in the earlier forges, was lined with fire-resisting scone (usually some variety of sandstone); but later, fire-bricks were used, and still later, iron plates, which in the more recent "blomaries" have been made hollow and kept cool by a circulation of water. The tuyère, b, was placed from seven to eight inches above the bottom of the hearth, and was contrived so that its inclination could be varied at pleasure. The blast was produced