Two thousand years ago the Romans, or their dependents, smelted iron in the county of Durham: vast accumulations of slag exist there at the present time; and thousands of tons have been beneficially re-smelted by two adjoining iron-works, and a percentage of iron obtained sufficient to prove that the Romans were little indebted to fluxes or hot blasts for the quality of iron they obtained. The Russians cannot boast of these adjuncts any more than the Romans: the old agents, wood and energy, are alone employed in the smelting of their ores; and in the absence of scientific aids, though they obtain a much smaller aggregate quantity of metal, yet it is undoubtedly of a much superior quality. With the Romans, also, the yield was meagre, but the quality was good; now, however, circumstances are reversed, quantity, not quality, being the order of the day. The use of coals instead of wood in the process of smelting has introduced a mixture which is very prejudicial. Most of the coal, even from our very best mines, contains a large quantity of pyrites, or bisulphuret of iron, which, combining with the cast-iron, injures it to an incalculable extent. These facts fully explain why our cast-iron guns are not so good now as formerly. Select the most suitable mine in the kingdom, erect a furnace on the most improved principles, employ wood fuel only, avoid fluxes and hot and cold blasts, and be content with the small amount of metal produced, and beyond all doubt the quality will be all that the most sanguine founder or artillerist could wish. Thus the inferiority of our cast-iron guns has been accounted for, and a method suggested, which, if efficiently carried out, would effect the desired improvement. * * * * * We are indebted to Krupp for the first suggestion of, as well as the first attempt to introduce, a cast steel gun of greater durability and power than the best cast-iron gun which has yet been manufactured. Steel, possessing, as it does, hardness to any desired extent, ductility in an equal degree, tenacity unrivalled, and all the other requisites, is destined to take the place of all other metals in the construction of artillery. This metal waits only to be tested; and the greater the extent to which the trial is carried, the more confident we are that it will answer every purpose. Krupp, like many other men with valuable ideas, has been peculiarly unfortunate in his attempts to carry them out. With a vast amount of knowledge of the science of metallurgy, he wants more knowledge in the not inferior science of projectiles; the most important point being to ascertain the form of gun calculated to be suitable for new metal, of the use of which, for cannon, the world possesses no antecedent knowledge.