|THE DEVELOPMENT OF AMERICAN INDUSTRIES SINCE COLUMBUS.|
II. IRON MILLS AND PUDDLING-FURNACES.
IN these days of steam-engines, railways, and steam navigation — telegraphs, telephones, and electric lights — it is hard to understand a civilization which in literature and the fine arts has not been surpassed, yet had none of the above-named essentials of modern fast living and rapid work, and which possessed no better methods of manufacturing iron than those already described.
It will be evident to the most superficial observer that these methods were not calculated to produce merchantable bar iron either rapidly or cheaply, and this fact would be the more manifest as the bars or rods decreased in size. Therefore, as the requirements of trade were mainly for bars and rods of moderate dimensions, from which to forge nails, draw wire, and manufacture multitudes of the smaller articles of hardware for which the settlement of new countries had created a growing demand, nothing could have been more natural than that the efforts of mankind to meet the requirements of the time should have resulted in the invention of the "slitting-mill." We have no precise information as to the date of this invention, and none whatever respecting its inventor. It is very probable that the slitting-mill was invented in Sweden, and carried thence into Germany, Belgium, and England, whence it found its way to the colony of Massachusetts Bay, where the first "slitting-mill" used in America was put in operation some time prior to 1731. Swedenborg, in his De Ferro (1734), speaks of "slitting-mills" in Sweden, Germany, Belgium, and England, but does not refer to their origin, and says nothing whatever of grooved rolls. Slitting-mills were introduced into England as early as 1697.
A "slitting-mill" comprises two principal mechanisms, which are well illustrated by Fig. 17, which, together with Figs. 16 and 18, we have taken from Recueil de Planches sur les Sciences et les Arts. Paris, 1765. In Fig. 17 will be seen —
1. A pair of plain cylindrical rolls, C D, placed the one above the other, each receiving motion, independent of the other, from a water-wheel, there being one on each side of the mill, whose shafts are seen at E and O. These rolls could be adjusted so that the distance between their adjacent surfaces might be varied within certain limits. These rolls equalized the thickness of the rough forged bar and prepared it for the next operation.
2. The "slitting-mill" proper, seen between the letters N and