Page:Popular Science Monthly Volume 39.djvu/762

742 furnace. Nevertheless, they succeeded in producing in it cast steel of excellent quality, of a variety of tempers, for which they were awarded a gold medal at the French Exhibition of 1867. The success of the Messrs. Martin, together with the fact that patents had been granted them for certain details of manipulation, brought about a combination of the interests of the Messrs. Siemens and Martin in the process, which has come to be known as the "Siemens-Martin open-hearth process." The construction of a small furnace for conducting this process is illustrated by Figs. 55 and 56—the first being an elevation showing the "ingot molds." arranged in order upon a traveling carriage, k, by which they are successively brought under the "tapping spout," b, to



be filled. Fig. 56 is a vertical cross-section, taken through the "charging door," a, and the "tapping spout" b, of the same furnace. Beneath the melting chamber will be seen the "regenerative checker-work," C, C, whose function and operation are the same as in the "pot melting furnace" already described.

The earlier "open-hearth" furnaces were like that illustrated, quite small, making but two or three tons of metal; but at the present time there are a number in operation of upward of twenty tons capacity, equipped with much more perfect apparatus for casting ingots than that shown in the engraving.

To the Hon. Abram S. Hewitt is due the credit of introducing the "Siemens-Martin" "pig and scrap" process into this country. While serving as one of the United States commissioners to the Paris Exposition of 1867, he became favorably impressed with the merits of the process, and sent Frederick J. Slade to Sireuil