The preceding pages will have done much to remove from an unbiassed mind any favourable impression of the advantages expected to result from the use of wrought-iron cannon. The knowledge of this subject, even among talented and scientific men, appears to be at a very low ebb, as is evinced by the multitude of failures that have taken place; not one success of any moment has as yet been attained, and not a discovery has been made worthy of being chronicled. * * * * * Having enlarged thus much on the qualities of a metal which it is certain can never supersede the use of cast-iron, even though it be freed from the defects found practically to exist in our present constructed iron artillery; and having also alluded to the fact that the _form_ has much influence on the durability of cast-iron guns, I now proceed to the more important point of the qualities of cast-iron itself. Little doubt exists that guns cast a hundred years ago were more durable than those of more recent formation; it is evident, therefore, that apart from mere form, some material depreciation must have taken place in the quality of the metal. The use of hot blast-furnaces, better fluxes, and improved chemical knowledge in the reduction of metallic ores, though highly profitable in a commercial point of view, doubling the products of our mines, and enriching their proprietors, has, unfortunately rendered English cast-iron perfectly unfit for the formation of cannon, if increased range and greater strain by high elevation are to be the order of the day. The durability of Russian cast-iron is unquestionably greater than that manufactured in England. Some cause must exist for this; and the question arises, is the ore superior to ours, or does the superiority of Russian iron depend on their method of smelting? The latter is, we believe, the cause of the superiority of Russian iron; for experiments show that Russian ore, smelted in an English furnace, yields the same kind of cast-iron as is produced from the ore found in England. The inference, therefore, is plain, that the difference in the process of smelting makes all the difference in the quality of the iron.