found that when the air had been blown into the iron till all the carbon was expelled, the continuance of "the blow" afterward consumed the iron at a very rapid rate, and a great loss of iron thus took place. It was therefore necessary to cease blowing at a particular moment. At first he saw no practical way by which he could prevent the metal going into the air-holes in the bottom of the vessel below the level of the liquid mass, so as to stop them up immediately on ceasing to force the air through them; for if he withdrew the pressure of air, the whole apparatus would be destroyed for a time. Here, again, his inventive genius found a remedy. He had the converter holding the molten iron mounted on an axis, which enabled him at any moment he liked to turn it round and to bring the holes above the level of the metal; whenever this was done the process of conversion or combustion ceased of itself, and the apparatus had only to be turned back again in order to resume the operation. This turning on an axis of a furnace weighing eleven tons, and containing five tons of liquid metal, at a temperature scarcely approachable, was a system entirely different from anything that had preceded it; for it he took out what he considered one of his most important patents, "and," he says, "I am vain enough to believe that so long as my process lasts, the motion of the vessel containing the fluid on its axis will be retained as an absolute necessity for any form which the process may take at any future time." The patent for this invention was taken out about four years after his original patent for the converter. Uncle Fritz showed them a picture of this gigantic kettle, which holds this mass of molten metal and yet turns so easily. "But," said Helen, "you have a model of it here, Uncle Fritz." And she pointed to her Uncle Fritz's inkstand, which is something the shape of a fat beet-root, with the point turned up to receive the ink. Uncle Fritz nodded his approval. These inkstands, which turn over on a little brazen axis, were probably first made by some one who had seen the great eleven-ton converters. Uncle Fritz showed the children the picture in the "Practical Magazine," and they spent some time together in looking over the pages of the volume for 1876. The Bessemer process was now perfect. Nearly four years had elapsed since its conception and first application; and in addition to the necessary labor and anxiety he had experienced, no less than £20,000 had been expended in making experiments that were necessary to complete its success. It only remained to bring the process into general use. * * * * *