The only failures Mr. Krupp has made (if they can, strictly speaking, be so called), have arisen from mal-construction, imperfect form, and unscientific combinations; defects which might be expected from a mere novice, though not from experienced artillerists or founders of artillery. The trial of the only steel gun sent by Mr. Krupp to this country, was conducted in the most absurd manner, and on wholly unscientific principles. I will endeavour to convey some idea of this most extraordinary of experiments. Whether Mr. Krupp was unacquainted with the durability of his metal, or was persuaded, against his will, to conduct the experiment as he did, I know not, but the following is what took place:-- In 1851 Mr. Krupp brought to Woolwich a specimen steel gun of ten-inch bore, weighing about four tons. He was induced (but why, I am at a loss to conceive,) to construct a cast-iron jacket, or outer gun, into which his steel gun was inserted up to the trunnions. The steel gun was separated from its cast-iron jacket by a space of half an inch in its whole length, except at each end, where the jacket was fitted to the gun with a moderate degree of tightness; thus the gun and jacket consisted of two tubes, one within the other, fastened only at their extremities, and that by a very slight force. The result, as might have been expected, was the bursting both of the gun and its case; but that the steel gun or its jacket would have stood the test, if subjected to it singly, cannot be doubted. The difference of expansion between the steel gun and its jacket would be quite enough to account for its bursting. Had the contact of the two been perfect throughout the whole length, but allowing half an inch all around for the expansion of the steel gun in that part which was subjected to the greatest pressure, the very act of restraining it in other parts so as to prevent equal expansion, would be perfectly certain to produce a fracture. Mr. Krupp’s friends have complained loudly of unfair treatment, whether justly or not, no opinion need now be given; but it is much to be regretted that his experiment was not carried out on scientific principles. The introduction of cast steel guns will be the most essential improvement in artillery: and an extensive series of experiments, extending over many years, during which time I have manufactured gun-barrels of steel alone, ought to give my opinion some weight on this subject.