We have just seen that iron is obtained in small masses. These can be welded upon heating them to 1,500 or 2,000 degrees. It is impossible to manufacture a large piece exempt from danger from the weldings. Cast iron always has defects that are inherent to its nature, and these are all the more dangerous in that they are hidden. Steel is exempt from these defects, and, moreover, whatever be the size of the ingot, its homogeneousness is perfect. This is what has given the idea of manufacturing from it enormous marine engines and those gigantic guns that the genius of destruction has long coveted. Ah, if the good sense of men does not suffice to put a limit to their increasing progress, bridges, viaducts, and tunnels will take it upon themselves, if need be, to bar their passage. But, in order to forge large ingots, it became necessary before all to increase the power of the steam hammer. The Creusot establishment, which endowed metallurgy with this valuable machine, had allowed itself to be eclipsed, not by the number (for it had 57), but by the dimensions of the largest one. In 1875, the Krupp works constructed one of 50 tons, and their example was followed at Perm, St. Petersburg, and Woolwich. It was then that Mr. Henry Schneider put in execution a bold project that he had studied with his father, that of constructing a 100 ton steam hammer, along with the gigantic accessories necessary (Fig. 2). It became necessary to erect a building apart for its reception. This structure covers a surface of one and three-quarter roods, and reaches a height of 98 feet in the center. As for the hammer, imagine uprights 25 feet in height, having the shape of the letter A, surmounted with a cylinder 19 1/2 feet in length and of a section of 31/2 square yards. [Illustration: FIG. 2.--THE CREUSOT ONE HUNDRED TON STEAM HAMMER.] The piston which moves in this cylinder, under a pressure of 5 atmospheres, is capable of lifting a weight of 100 tons. The hammer, which is fixed to this piston by a rod, has therefore an ascensional force of 88,000 pounds. It can be raised 16 feet above the anvil, and this gives it a power three and a third times greater than that of the Prussian hammer. Large guns can therefore be made in France just as well as in Germany. This enormous mass is balanced in space at the will of one man, who, by means of a lever, opens and closes two valves without the least effort. This colossal hammer required an anvil worthy of it. This weighs 720 tons, and rests upon granite in the center of 196 feet of masonry.