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Rh out and cut into small rods; and in Germany and England there is similar machinery, constructed as shown in Fig. 19, which vividly represents the whole operation.

"The furnace shown is simply constructed, and is divided into two parts, beneath each of which is an ash-pit. The iron is thrown into the furnace upon the mineral coal (carbones fossiles) and the bars are placed across one another obliquely, so that the flame and heat will have access to all sides of them. The roof of the furnace is formed into an arch. When the pieces of iron are heated by the direct action of the coal, and by the heat reverberated from the roof of the furnace, they are removed and run through two steel rolls."

By comparing this mill and furnace with those illustrated in Figs. 17 and 18, it will be evident that in the thirty-one years which intervened between the publication of De Ferro and Recueil de Planches sur les Sciences et les Arts important progress had been made in the construction of both mills and furnaces.

We have been thus particular in explaining the construction of the early European slitting-mills because it is certain that many of the ideas embodied in the first American slitting-mill were derived therefrom.

Industrial history is indebted to William H. Harrison, of Braintree, Mass., for the preservation of a record of the details of construction of certainly one of the earliest, if not actually the first, rolling and slitting mills built in America. The general plan and elevation of the machinery, as also of the furnace employed in this mill, are shown in Fig. 20, and it will be noted that the natural tendency of the American mechanician to improve on what had already been accomplished asserted itself in this case. The designer while retaining many features of previous mills—such as wooden gearing, the use of two under-shot water-wheels, one of which drove the top set of cutters and the bottom roll while the other drove the bottom set of cutters and the top roll—yet made some important improvements in the rolls by increasing their length and making offsets in them by which iron of vary ing thickness could be made without changing their adjustment; and he also "chilled" one end of the rolls. The furnace was a marked improvement over any before described, and was quite similar in idea to many in use at the present day; it had a "fire-box" (in which "pine sticks" were used as fuel), a "heating-chamber," and a "chimney." This mill was erected "at