The steam-hammer, be it known, is the application of steam to a piston under complete regulation, so that the piston, armed with a hammer, regularly, steadily, perpendicularly descends as desired, either with the force of a hundred tons or with a gentle tap, just sufficient to drive home a tin tack and no more. At a word it stops midway in stroke, and at a word again it descends with a deadly thump. On our visit, an attempt was being made to execute in wrought, what had hitherto always been made in cast iron. Success would effect a great saving in weight. The doors of the furnace were drawn back, and a white glow, unbearable as the noon-day sun, was made visible, long hooked iron poles were thrust in to fish for the prize, and presently a great round mass of metal was poked out to the door of the fiery furnace--a huge roll of glowing iron, larger than it was possible for any one or two men to lift, even had it been cold. By ingenious contrivances it was slipped out upon a small iron truck, dragged to the anvil of the steam-hammer, and under the direction of Vulcan, not without his main strength, lodged upon the block. During the difficult operation of moving the white-red round ball, it was beautiful to see the rapid disciplined intelligence by which the hammerman, with word or sign, regulated the movements of his young assistants, each armed with an iron lever. At length the word was given, and thump, thump, like an earthquake the steam- hammer descended, rapidly reducing the red-hot Dutch cheese shape to the flatter proportions of a mighty Double Gloucester, all the while the great smith was turning and twisting it about so that each part should receive its due share of hammering, and that the desired shape should be rapidly attained, sometimes with one hand, sometimes with the other, he interposed a flat poker between the red mass and the hammer, sharing a vibration that was powerful enough to dislocate the shoulder of any lesser man. "Hold," he cried: the elephant-like machine stopped. He took and hauled the great ball into a new position. "Go on," he shouted: the elephant machine went on, and again the red sparks flew as though a thousand Homeric blacksmiths had been striking in unison, until it was time again to thrust the half-welded cheese into the fiery furnace, and again it was dragged forth, and the jolly giant bent, and tugged, and sweated, and commanded,--he did not swear over his task. At length having succeeded in making the unwieldy lump assume an approach to the desired shape, he observed, in a deep, bass, chuckling, triumphant aside, to the engineer who was looking on, "I'm not a very little one, but I think if I was as big again you'd try what I was made of." Since that day we have learned that the experiment has been completely successful, with a great diminution in the weight and an increase of the strength of an important part of a locomotive.