arose from his knowledge of the great inferiority of wrought-iron, as compared with steel, for such a purpose, and also from his practical experience, as an artillerist, of the searching and highly corrosive nature of the intensely-heated powder gases, which, sooner or later, find out and deeply corrode the numerous imperfectly-welded joints inevitable in a wrought-iron gun tube.

The natural effects of corrosion on wrought-iron bars must have been commonly observed. Take, as an example, an old pump-handle, and see how the once smooth and even surface is eaten into deep grooves and furrows by corrosion, commencing at, and following, all the lines where the several parts, of which the bar is composed, are imperfectly welded together. Or examine an old chain cable, the links of which were made of smooth round iron rods, and see the indented shape it has acquired, the once smooth surface of each link being grooved by corrosion of the metal where the parts were imperfectly welded in the original formation, even of the high-class iron used for cables. This is the effect of water only on ordinary wrought iron. If any one doubts the destructive effects of fluids more corrosive than water, let him put a bright, well-finished piece of bar-iron into water containing only one-tenth of its weight of sulphuric acid, and he will find that in less than one hour he will have a perfect picture of the arrangement of parts of which the bar is composed, showing all the imperfectly-welded fibres, like a beautifully engraved map. What, then, must be the result from the union of the oxygen in the saltpetre with the sulphur in gunpowder, producing sulphuric acid gas, acting under enormous heat and pressure within the gun, and searching out and attacking all its welded joints?

In my search at the Patent Office, I also found the provisional petition of Mr. William George Armstrong (afterwards Lord Armstrong), dated February 11th, 1857, being two years less sixteen days after the patent of Captain Blakeley, which is dated, 27th February, 1855. Annexed is a copy of Mr. Armstrong's provisional specification, issued under the authority of the Commissioners of Patents :-

(This Invention received Provisional Protection only.)

PROVISIONAL SPECIFICATION left by William George Armstrong at the Office Of the Commissioners of Patents, with his Petition, on the 11th February, 1857.

I, WILLIAM GEORGE ARMSTRONG, Of Newcastle-upon-Tyne, in the County of Northumberland, Civil Engineer, do hereby declare the nature of the said Invention for "Improvements in Ordnance," to be as follows :-

The improvements relate, firstly, to forming guns with the internal tube or cylinder of wrought iron or gun metal in one piece, surrounded by one or more cylindrical casings of wrought iron or gun metal shrunk upon the internal cylinder.

It will be seen that this proposal of Mr. W. G. Armstrong differs from the invention set forth in Captain Blakeley's prior patent, by substituting a wrought-iron internal tube for a steel one. As I could not lawfully make a built-up gun with collars or rings shrunk or forced on to a steel tube, and as I had no intention of evading Captain Blakeley's patent by using an inferior material for the inner tube of the gun, I abandoned all idea of the manufacture of built-up guns, and contented myself with supplying Captain Blakeley with steel tubes, or with forged steel guns complete in one piece, with the trunnions formed thereon out of the solid ingot. This manufacture I commenced as early as February, 1861; between that date and February 5th, 1863, I had manufactured at my works in Sheffield no less than seventy forged steel guns for foreign service, not one of which was ever returned to me, or was reported to be in any way defective.

All these orders for guns came to me spontaneously, and were never sought for by travellers, advertisements, circulars, or otherwise. But not one gun, or gun-block, was ever ordered of me by the British Government to test the qualities of this new steel, which at that period was the subject of the deepest interest and most careful examination by intelligent engineers in every State in Europe.

In the early part of the year 1859, the Bessemer Steel Works at Sheffield had regularly embarked in the manufacture of high-class steel for tools, and also for cutlery. For this purpose I had investigated the