As represented in Fig. 72, Plate XXXI., this shocking example proved too much; it was, in fact, so bad a plate that, if originally made of such an unheard-of quality, it could never have been either rolled or sheared in the makers' works without proclaiming its utterly valueless character to every workman engaged in its manufacture. It must not be forgotten that it is physically impossible for the Bessemer process to produce a single isolated plate of such a bad quality, for the simple reason that Bessemer steel is never made in less than 5-ton batches, every part of each "blow" being equally good or bad. Now, after deducting 20 per cent. for waste in shearing, these five tons of homogeneous fluid steel will produce twenty-three ship-plates, 8 ft. long by 3 ft. wide and 3/8 in. in thickness. All of these twenty-three plates must, therefore, be equally good or bad, so that one bad plate alone could not be made, though any number of good plates may be spoiled by an ignorant, careless, or designing workman. The exhibition at a public meeting of such an unheard-of specimen of steel plate, and the proclamation of the "uncertainties and treacheries" of Bessemer steel, together with other damaging statements, by a person holding high authority, compels me to discuss the above-named paper at some length, and in justice to myself, to show that Bessemer steel is now and was then, in reality, a metal immensely superior to ordinary puddled iron, and that the example exhibited at the meeting in no way represented its true character and properties.

In order to clearly understand this question of bad plates, it is important to bear in mind that the iron plates used by shipbuilders were infusible in any of the heating furnaces that were to be found in shipyards at that date. Hence an iron plate worker could leave an iron plate in the furnace, and make it very hot with impunity. But cast steel, as its name implies, has undergone fusion, and if ever it again be subjected to an unnecessarily high temperature, approaching its point of fusion, its molecules rearrange themselves, and the valuable qualities conferred on the cast ingot by hammering and rolling are lost in proportion to the amount of overheating it may have been subjected to; so that, at a temperature quite possible to be given to it by a careless or ignorant workman, it becomes almost like the normal unwrought ingot from which it was formed. But this property of cast steel is so well understood by the practised steel- smith that he will pass hundreds of plates, or other articles, through any of the processes of heating in the furnace, tempering, hardening, or annealing, without the smallest injury to any one of them. It is the unpractised iron-worker, who does not understand the properties and mode of working steel, who makes mistakes of this kind.

It must also be observed that neither at the date about which I am writing, nor at any subsequent date, has it been possible to make cast steel which could not, either by ignorance, carelessness, or design, be rendered unfit for use by overheating it. Such liability to damage is not peculiar to steel made by the Bessemer process, since this quality is common to cast steel, however manufactured. When the molten cast iron in the Bessemer converter has been decarburised by blowing air through it, and has been poured into an ingot mould, the Bessemer process is complete; and such an ingot, like every one made in crucibles, or by the Siemens or open-hearth process, may be treated properly and make an excellent plate, or it may be treated improperly and be rendered worthless. The Bessemer process, like all others, may also make bad steel, if raw material of inferior quality be used in its manufacture. Sir Nathaniel Barnaby neglected to use the most perfect, and, at the same time, the only possible, means at his disposal of proving beyond dispute if the particular piece of plate, which he held up to the meeting, owed its bad quality to the Bessemer process, or to improper treatment after it had left the converter in a pure state. If he had had this sample of steel carefully analysed before he condemned it publicly, he and his audience would have known whether it contained such an amount of phosphorus, sulphur, or any other deleterious matter, as would account for the extraordinary cracking at so slight an angle, or whether the steel was free from these deleterious matters; or if it was of excellent quality when it left the converter, and had been spoiled afterwards by its treatment in the shipyard. Unfortunately, nothing was told us in this incomplete paper as to how, or by whom, this little sample was prepared for exhibition. Was the workman who made it a steel-smith, or was he an iron-worker, ignorant of the nature and proper treatment of cast steel?

If an actual plate, which had failed in the course of shipbuilding, had been shown at the meeting, it would have been much more satisfactory than a sample-piece, by whomsoever made, and such an actual