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Page:Popular Science Monthly Volume 38.djvu/167

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greater profit, then more perfect plans were made, and higher furnaces, having greater capacity and more solid walls, were constructed."

The reverberatory furnace had been employed in Europe from the earliest times for the melting of brass and other metals; and for heating them dry wood was the usual fuel. Benvenuto Cellini (about 1547) erected such a furnace for melting the bronze for his statue of Perseus; and he expressly states that he commenced the melting with "pine wood, which, because of the oiliness of the resinous matter that oozes from the pine tree, and that my furnace was admirably well made, burned at such a rate, that I was continually obliged to run to and fro, which greatly fatigued me"; and, after describing various troubles in getting the metal melted, he finally completes that operation by the use of "a load of young oak, which had been above a year in drying."

From a French work on the construction of artillery[1] we take Fig. 4, which is a very spirited illustration of a reverberatory furnace at the moment when the metal is being tapped into the molds. In this figure A is the furnace; B, the furnace-doors, which are made of iron; C, chimneys of the furnace; D, firehole; E, frame of carpentry above the pit, to which is attached the pulleys and other tackle which serve to lower the molds into the pit and remove the castings made; F, pit (made in the earth), in which the molds are placed; G, "runners" with "gates" for the metal; H, workmen who split the wood and carry it to the furnace; I, workman who throws the wood into the fire: the wood falls upon a grate which is at the bottom of the fire-box, three feet or more below the part of the furnace containing the metal; K, cover, or paddle of iron, for closing the mouth of the fire-box; L, workmen who raise the furnace-doors by means of a lever; M, lever for raising furnace-doors; N, workmen who stir the melted metal with poles of wood, and who remove the slag and refuse metal with tools called "rabbles"; O, the master founder, with the tapping-bar, opening the hole by which the metal is discharged into the "runners"; around him stand a group of interested visitors. After this description we are told that "the furnace at Douay contains sixty thousand pounds of metal." This would not be regarded as a small furnace even now.

As illustrating how the metal was taken from the early blastfurnaces for the making of "sowe iron" and castings of various kinds, we reproduce[2] Figs. 5 and 6. In Fig. 5 workmen, numbered 1 and 2, are seen making an open mold of triangular crosssection in the floor of the "foundry," in which is to be cast a sow,

  1. Memoires d'Artillerie, 1647.
  2. From Recueil de Planches, sur les Sciences, les Arts Liberaux, et les Arts Méchaniques avec leur explications. A Paris, 1765.