The CHAIRMAN.-You have mentioned an experiment with respect to two portions of the same plate. Do you know as a fact which portion was upon the weak backing, and which upon the strong? Capt. HALSTED.-I do not say even in my paper that I do. What I say is, that no other assignable cause can be given for it. Your The CHAIRMAN.-But your deduction may be the opposite of the fact. implied deduction is, that the plate that was upon the weak backing was destroyed; whereas the plate that was on the strong backing was not destroyed. Capt. HALSTED.-That is, of course, the deduction. I mean to say that no other assignable cause can be found for it. The CHAIRMAN.-But the fact may be the reverse of what you suppose. The portion of plate that was upon the weak backing may have been less damaged than the portion of plate that was on the strong backing. I want to know what was the fact. You merely surmise, and draw a conclusion from a surmise. It is an awkard conclusion to come to on mere surmise. Capt. HALSTED.-It is not a mere surmise. If you will permit me just to point out to you there is that very 10-inch plate which the 100-pound shot went through the other day without any backing. I do not hesitate to say, if it be the case that that was done by Sir William Armstrong's 100-pounder gun, with well-hardened steel shot, manufactured for the purpose, that it was nothing more than the gun which fired at the "Trusty"-not the same identical gun, because the conditions are different. I asked Sir William Armstrong at the Institution of Engineers the other night these questions: "Is your 100-pound gun at this moment above or beyond, or in any way different from, the 80-pound gun with which you fired at the Trusty,' and out of which you then fired 100 pound shot at 200 yards? Do you use a larger charge?" His answer was: "No-it is the same 100-pound shot." I asked, "Is your gun the same length?" "It is of the same length." Then I said, "My conviction is, that your new 100-pound gun is not so formidable a gun for penetration as the old 80pounder gun out of which you fired that 100-pound steel shot, and which is now rejected. For this reason," I said, "for the sake of getting a larger shell, you have now adopted a 7-inch calibre, instead of a 6-inch calibre. The whole force from the same charge of powder, the same weight of shot, the same material, fired from the same length of gun, was then concentrated over a square of 6 inches-call it 36 inches; it is now dispersed over 49 inches, the square of 7 inches. Therefore," I said, "the plate has got one-third more advantage than it had then; independently of which, the fact was then that you could not penetrate." The CHAIRMAN.-This is mere argument, and contrary to all analogy. The CHAIRMAN.-I would appeal to the engineers present whether it is not contrary to analogy. I would observe, with respect to the "Trusty," that, wherever the side was of greater substance, that was the part most effectually pierced. Capt. HALSTED.-They did not fire at those parts. The CHAIRMAN.-Never mind whether they fired. The effect was such-I tell it you as a fact; I saw it with my own eyes. I do not know whether they fired at it; but I know they hit it. Capt. HALSTED.-They expressly fired away from it. The CHAIRMAN.-You are aware, if you want to punch a hole, you do not put the plate on a yielding surface. If you want to punch a plate, the more solid the structure you rest it upon, the more completely do you punch it. W. FAIRBAIRN, Esq. F.R.S.-I think both the naval and military services are much indebted to Captain Halsted for his very valuable papers; I have not had the opportunity of being present at any of the lectures, except this one to-night, but I have read two of them, and I was very much gratified to find that Captain Halsted had taken up the subject in the way he has done. He directs public attention to a subject of very great national importance, as affecting the security of the country at large. Connected as I am with the Committee upon iron plates, I am not prepared, at this stage of the experiments, to give any information. I am, however, inclined to think that the ultimate results will be that the whole of our navy, so far as I can judge, mus tbe constructed of iron. I have paid some attention to Captain Halsted's observations with regard to the "Warrior," and I quite agree with him that it would be much better to have the armour-plates carried round the bows and also round the stern. But it is yet to be proved whether the 4-inch or 4-inch plates are impenetrable to shot, particularly from ordnance of very large calibre. I have no doubt, from the present improvements that are going forward with regard to artillery, that we shall have guns that will break if not penetrate 6-inch plates. It is a question to be proved, whether we may not have to increase the thickness of our armour-plates to a degree that may exceed the limits of any vessel to carry them, or to raise the centre of gravity so high as to makethem unsafe. With respect to the impact of shot and projectiles at high velocities, I am quite of opinion that it is necessary to give such an amount of protection as may be essential for the security of the ship and of those on board. Some twenty-five years ago I was in correspondence with the Admiralty, when I first commenced iron-ship building in London. I was extremely anxious to ascertain the effect of shot on iron plates; but I received no answer for nearly two years; at last I did get an invitation to attend at Woolwich. It was in Sir George Cockburn's time. I was present at the experiments then made; but those experiments were on comparatively thin plates-double 1-inch plates. Then we tried wood behind, and another 4-inch plate after that, but they did not resist a 36-pound shot. The shot went through them quite easily. The Admiralty got alarmed in consequence of the number of splinters which were dispersed in every direction; they were jagged, ugly missiles. In order to absorb these as much as possible, we put india-rubber and sawdust 12 inches thick between the second and third plates. Some particulars of these experiments I have already published, to show to what extent they were carried at that time. But, until the Emperor of the French came forward with his 4 and 44-inch plates, we had no idea in this country to make such a provision with regard to the safety of vessels. I still hope that the Committee with which I have the honour to be connected may be able from experimental data to give the law with regard to the thickness of plates necessary to resist projectiles at all velocities. I may add, as a member of the Committee, that in conducting the experiments now in progress, they are most anxious to arrive at results calculated to increase the efficiency and security of the British navy. Commander ROBERT SCOTT, R.N.-As Mr. Fairbairn has said, we cannot but feel greatly obliged to Captain Halsted; and if others would come forward and speak in the same open and candid manner, the difficulties in which the iron-plate question is at present involved would be soon cleared up. The plate committee's having begun with very thin plates has been commented upon, but it is surely the best plan to commence thus, and to go on gradually increasing the thickness of the iron. I need not go further into this, as the committee's plan is one which I think most will admit to be likely to produce definite results. Captain Halsted has spoken of the effects of two Armstrong 100-pounders of different sizes. The one is of 6 inches bore, and formerly threw a.100lb. shot, and was fired with 10lbs., and sometimes with 12lbs. of powder, but it now fires an 80-pound shot, and is called an 80-pounder. The other gun has a. bore of 7 inches, and a charge of 12lbs. of powder, which is occasionally increased to 14lbs. Supposing that both these guns of 6 and 7 inches calibre, respectively, fired 100lb. shot with 12lbs. of powder; the velocity of the 7-inch diameter shot would be greater than that of the 6.inch, from the larger area of its rear for the powder to act upon; the present 100-pounder is, however, a more powerful gun in every way than the old one; but in both these guns, as in all the finely-grooved ordnance, a great portion of the force of the charge is expended in forcing the lead through the grooves. There is now a new gun with three grooves, called the Shunt, which is also on the compression system, but the friction being on three points only, and the charge of powder 18lbs. for a projectile of 120lbs., very destructive effects are produced by it on iron plates. In the recent experiments the shot from this gun are said to have not only broken the 8-inch bars of the Thornycroft embrasure, but also cracked the 10-inch bars, which had previously resisted the fire of the smooth-bore 68, and the Armstrong finely-grooved guns. But the conditions under which the firing took place against these bars, and that which would be the case against a ship's side, are really very different. And I do not think that any just conclusion can be arrived at from this experiment, for the dovetailed bars rested upon a solid foundation, being built up perpendicularly, layer upon layer. The CHAIRMAN.-Not backed nor supported? Commander SCOTT.-They were supported by iron bands and fastenings behind. Commander SCOTT.-None. These bars, having little elasticity, were soon broken by the shot from the Shunt gun, which was placed exactly opposite, so that they were hit with the full force of the shot at right angles. On the other hand, a ship is always in motion, and will be seldom if ever struck so advantageously, and a ship will always have a large amount of elasticity; and should the side be sloped inwards it will be impossible to hit it perpendicularly to the plane, with an elongated shot. With the round ball the case will be somewhat different, for the round ball rolling over in the bore, leaves the gun rotating, and will thus fall down upon a sloped side; and, although its penetration into iron is less than that of the flatheaded projectile, it causes more destructive effects to the structure covered by the plates. In some of the Shoeburyness experiments against a casemate protected by iron, the rear was found to be very much shaken after the firing of the solid 68-pound round balls, although the previous practice with the elongated projectiles had only injured the plates in front of the casemate. And it is well to bear in mind, that in the cutting of an iron plate by a flat-headed projectile, a great portion of the force of the blow is absorbed, and hence less concussion is produced than with the round ball, which has also the advantage of a much greater velocity within the distances for effective warfare at sea. The experiments against the "Alfred" and “Trusty are a good illustration of the remarkable differences in the effect of round and elongated shot. The "Alfred" was fired at with round shot, and, having personally examined her, I can vouch for very good oak having been smashed behind the plates, in fact two ports were knocked into one, and the whole side of the vessel badly shaken. The "Trusty," on the contrary, was comparatively little shaken, because the elongated shot pierced the plates; but I feel satisfied that if a concentrated broadside of 68-pounders were to be fired at a short distance, the "Trusty's" side would be smashed in. At close quarters, the smoothbore 68-pounder has a very decided advantage over the finely-grooved 100-pounder, for it can be fired far more quickly and with greater safety; and depend upon it we shall always fight at close quarters. Take away the dash of our seamen, and the perfect confidence with which they rush into a hand-to-hand fight, and where will British naval superiority be? Therefore let our vessels mount the well tried 68-pounder with its simple round ball, then concentrate the fire, and I feel sure that no iron plates hung upon an upright side will stand more than two broadsides without coming down. I now wish to mention how, in my opinion, the present vessels could be rendered available; but I desire first to again bring before you, that unless the outer surface of the fortified vessel yield to or absorb the blow, the force exerted must be transmitted to the structure itself. This indicates the necessity that exists for breaking as far as possible the contact between the bottom or vital part of the ship and the top-sides. And in my opinion it shows, that, were a vessel to be wholly built of iron of 6 or 7 inches in thickness, the bolts uniting the iron planking would be broken by the concussion resulting from the blows of broadsides, or even from a succession of single heavy shot; and that the vessel would be soon shaken to pieces by the excessive vibration produced by such hammering. What I would propose is, to have iron sides built up upon ribs fastened together at the bottom and on the inside of our wooden liners, which should be first cut down to the lower port-sill. Capt. HALSTED.-Cut the lower port-sill out? Commander SCOTT.-Cut the vessel down to the level of the lower port-sill, and then bring the iron ribs to rest upon a bed inside the vessel; this would leave the full breadth of flotation, and keep the weight inside, giving iron top-sides with the advantage of a wooden bottom. The ribs to which the iron planking should be fastened would rest upon the keel and bilges, with a spur or flange thrown over the whole length of the upper edge of the wood, so as to effectually cover and protect it. From this spur the iron top-sides should be continued upward with considerable convexity, becoming gradually thinner as they sloped more and more inwards, but from the spur downwards a considerable thickness of plate should be used. Iron being nearly as good a conductor of vibration as of heat, an elastic or fibrous substance should be placed between the iron ribs and the plating or planking, and also between the iron ribs and the wooden bottom; these ribs, being firmly bolted together, would establish a continuity of vibration which would be expended round them, and thus prevent any heavy jar or concussion from falling upon the wooden bottom. As to the effect of artillery upon this structure, the weak molten iron shell would not penetrate the iron top-sides, nor set the wooden portion below that on fire, for fire will not burn against iron, unless there be a hole through both wood and iron to cause a thorough draft. Mr. Samuda's experiments are, I think, conclusive on this point. An elongated flat-headed shot,with a shell in 265 the rear, would, however, be more difficult to keep out; but, although it might damage Mr. SAMUDA. If I may occupy a few moments, with regard to the subject before us, it would be to speak on the general rather than on the particular detailed points which this discussion has brought up, and which principally invites our special attention. I think on the whole the remarks which Captain Halsted has made, with reference to the imperfection of a partial covering, cannot be too strongly insisted upon. The exemplifications which he has given are very good, and lead to the conclusion that it is impossible for a vessel only partially protected successfully to encounter a vessel with the same weight of metal when fully protected. A portion of the guns of the protected vessel may be, as he has described, directed to keep in check the centre guns of the unprotected vessel, and the result must be to render the unprotected vessel a complete floating wreck, by the destruction of her two ends. I think a great mistake has been made in leaving the ends of the " Warrior" uncovered, and I drew the attention of the authorities to that point in the strongest manner imaginable. I am perfectly ready to admit that no man in the three kingdoms has done more to draw attention to the importance of iron-clad ships, and to give a greater advance At the same time, I must say, that I think to the question, than Captain Halsted. he is wholly and entirely wrong in the conclusions he has formed as to the way in which the iron plates are useful in resisting shot. His conclusions as to the value of the backing in the one case, and the want of it in the other, are in my opinion radical mistakes. I believe Mr. Scott has entirely hit upon the real difference of the two experiments; namely, that the quicker velocity at which the round shot leaves the gun is the cause of the much greater destruction, in the Portsmouth experiments, than the slower velocity of the elongated shot in the "Trusty" experiments. If there were any value whatever in Captain Halsted's observations, if he had the smallest real ground for supposing that it was due to the imperfection of the sides of the ships that were fired at in the Portsmouth case, I can assure him that when I went down and examined the "Trusty," at the request of the Admiralty, with a firm belief and conviction on their part that it would put an end entirely to the necessity of building iron ships, I came back with a totally different conclusion; I came back with a conviction that we must come to nothing but iron ships in our navy. I brought back some of the backing-a quantity of stuff which resembled snuff. There was not Therefore, how could he have a piece of backing of any description or kind against those plates; the wood was totally rotten; and yet the plate resisted the shot. advocated the usefulness of backing from this case, and spoken of the plate It is impossible fairly to do so. breaking from want of backing in another case? will not trouble you with repeating the whole case, because I have said it two or three times before, and it has already got into print. Further observation shows me that the yielding quality derived from the elasticity of wood is much greater than the elasticity of iron-the particles of iron are in so much closer contact with one another than the particles of wood, that before the iron can receive any assistance from the wood it must necessarily yield to a degree which causes it to break. Now, I think that Captain Halsted has drawn an erroneous opinion with respect to the case of the anvil. In the first place, any man who puts an anvil upon a number of piles like that (see Plate IV.) It is found by experience, that the very best thing would commit a grievous error. you can do to make an anvil last is to do away with piles and solid foundation, and lay a quantity of wood under it, not by way of making a backing to resist the blows, but by way of making such a yielding quality, in the elasticity of the wood, T VOL. V. I that the anvil will yield to a certain extent to the hammer, and not break. It is entirely the reverse of what Captain Halsted thinks. I have told him that before, and have explained to him the error that any person would commit who should put a very firm unyielding foundation under the anvil. Again, with the great candour that Captain Halsted has shown all through his papers, he has made an observation to-night which has rather surprised me. He spoke of a 10-inch plate being broken through by one of these shots, now no 10-inch plate has been broken through, I have attempted to explain that the whole value of a plate to resist a shot consists of its immoveability, and its immoveability is due to its weight. It is an anvil, and the shot is a hammer. Instead of being a 10-inch plate, it has in reality been nothing more than a bar 4 inches on the face and 10 inches deep. The expense which our manufacturers have been put to in tongueing and grooving plates, to my mind, has been wholly useless. These 10-inch plates are in reality only 44-inch by 10-inch bars, and they have a series of grooves cut out to weaken them on top and bottom, though it is supposed that the grooving has the effect of rendering the plate and the one next to it perfectly and absolutely solid. The value of a plate in resisting shot would be the value of a 10-ton anvil if the plate weighed 10 tons, and were sufficiently compact to distribute the strain of that blow to the remotest corner of the plate. But to put a number of these piled up one upon the other like bricks, gives the plate no more value in receiving assistance from the adjacent parts than a brick would have in receiving assistance from adjacent bricks, to resist being driven out with a hammer of the size of a brick. I am surprised that Captain Halsted should have put that before the meeting without giving it the opportunity of knowing the facts properly. While upon this point I will draw your attention to the subject of tongueing and grooving plates. The plates by this plan get no strength from the adjacent plates, none whatever; it is impossible to make the fit so accurate as to prevent the particles from moving against the other plate. I admit that a backing of iron would give strength to an iron plate, both articles being of the same density; but you cannot get strength from the tongueing and grooving, because you cannot get grooves to fit one exactly into the other. You have the same result from the tongue and groove as if you had a plate one-third the thickness; and if you have one plate one-third the thickness instead of a whole plate, you only have one-third the strength. Then again you weaken the plate very extensively, just above the tongueing and grooving, by the holes which you have to drill, to attach it to the skin of the vessel. You will find that for a distance of about a foot each side of the plate, or in round numbers for about one-third of the entire height of the armour of the ship, you increase materially the weakness of your armour below the strength which is due to the amount of weight in the plate itself. It is the most important mistake that could possibly be made. That mistake existed to a greater extent in the vessels which were built in 1855, when a series of holes were made along the centre of the plates in a straight line, thus weakening the plate still more. This plan has been partially given up in the present ships; but it still exists at the edges, and is increased by the tongueing and grooving in the way I have stated. Then with regard to the advantage of elasticity, I think another mistake has been made. I do not know whether it was Captain Scott or Captain Halsted, who said something to the effect that the pliability of iron against wood would give some advantages. Commander SCOTT.-Not the iron against the wood, but the wood against the iron. Mr. SAMUDA. The wood against the iron has undoubtedly advantages in breaking the force of the blow. There are some disadvantages in it, but if you are bound by any necessity to have a defence, consisting of wood and iron, the right place is to put the wood in front, and not at the back. Commander SCOTT.-Will you kindly mention your experiments with molten iron? Mr. SAMUDA.-I made a target that represented the sides of the "Warrior" and "Black Prince." It consisted of teak 18 inches thick, and an iron plate, which would represent the armour-plate, if the "Warrior" were turned inside out. I made a hole in this plate 5 inches in diameter, and put into it a red-hot shot, as hot as it possibly could be made-so hot that it broke to pieces by the heat. I found that you could not possibly keep it alight more than fifteen minutes. At the end of that time, through the want of air, it went out. Finding that so successful, I tried the experiment of pouring in molten iron. I made it much hotter than you can ever hope to make it in shot and shell. I put it in direct from the furnace; I poured in 10 pounds of it from |