In the supreme effort of his life Bessemer once more held himself a debtor to his ignorance, to the fact that his mind was unworn by routine and ruttiness. Referring to his attempt to make a cheap metal stronger than cast iron for guns, he says: “My knowledge of iron metallurgy was at that time very limited, and consisted only of such facts as an engineer must necessarily observe in the foundry or smith’s shop; but this was in one sense an advantage to me, for I had nothing to unlearn. My mind was open and free to receive any new impressions, without having to struggle against the bias which a life-long practice of routine cannot fail more or less to create.” Now appears the genius of the man, showing that if his brain was unoccupied by rules-of-thumb it was full to overflowing with original and sound ideas. He goes on to say: “A little reflection, assisted by a good deal of practical knowledge of copper and its alloys, made me reject all these from the first, and look to iron or some of its combinations, as the only material suitable for heavy ordnance.” Of fascinating interest is the great inventor’s story of how step by step he arrived at his final success. After reciting his preliminary experiments, in an endeavor to remove carbon from pig iron so as to make malleable iron and steel, he says: “On my return from the Ruelle gun-foundry I resumed my experiments with the open-hearth furnace, when some pieces of pig iron on one side of the bath attracted my attention by remaining unmelted in the great heat of the furnace, and I turned on a little more air through the fire-bridge with the intention of increasing the combustion. On again opening the furnace door, after an interval of half an hour, these two pieces of pig still remained unfused. I then took an iron bar, with the intention of pushing them into the bath, when I discovered that they were merely shells of decarburized iron, showing that atmospheric air alone was capable of wholly decarburizing grey pig iron, and converting it into malleable iron without puddling or any other manipulation. Thus a new direction was given to my thoughts, and after due deliberation I became convinced that if air could be brought into contact with a sufficiently extensive surface of molten crude iron, it would rapidly convert it into malleable iron. Without loss of time I had some fire-clay crucibles made with dome-shaped perforated covers, and also with some fire-clay blow-pipes, which I joined on to a three-foot length of one-inch gas pipe, the opposite end of which was attached by a piece of rubber tubing to a fixed blast pipe. This elastic connection permitted of the blow pipe being easily introduced into and withdrawn from the crucible which, in effect, formed a converter. About ten pounds of molten grey pig iron half filled the crucible, and thirty minutes’ blowing was found to convert this metal into soft malleable iron. Here at least one great