24 MARCH 1860, Page 14

SHOTS A.ND SKIPS.

Belfast, 13th .3farch, 1860.

Slit—I see that Sir William Armstrong has succeeded in sending a missile through an iron plate of four inches and a half in thickness. I do not yet know at what distance this has been done, but I suppose it was not less than may reasonably, be expected in war. If Sir William Armstrong can do this, of course, Mr. 'Whitworth can do as much, or very probably more.

What then is the use of plating ships with iron ? It has frequently been said that ships cannot be made shot-proof, but they may be made shell- proof. This would probably be true if both shot and shell were necessarily spherical: but the introduction of rifled-cannon has got rid of this condi- tion and is leadhig to the introduction of cylindrical bolts, with conical points for penetration. The proportion of the length of the bolt to its dia- meter is of course not yet fixed, but it will probably in all cases be very con- siderable—perhaps never less than two-and-a-half or three to one and every increase in skill will tend to increase that proportion : so that there will be nothing to prevent the hinder part of a bolt from being hollowed out for a charge of explosive materials or of melted iron while the conical point is made of steel for penetration : and such a shell will have equal penetrating power with a solid shot of equal weight. There is no more speculation in all this. Such results are already much more than half attained ; and, when they are fully attained, it is difficult to see what other effect the iron plating of our " steam-rams " can have, than to lessen their buoyancy, and consequently either their speed or their power of carrying cannon. fthink that, ten years hence, such vessels will be universally condemned as costly failures.

I do not mean, however, that we ought to go back to the old line-of- battle ships and frigates. It is "putting too many eggs in one basket" to expose a ship with a hundred guns and a thousand men, to the chance of enormous damage, and perhaps total destruction, from a single shell ; and, if any one is inclined to think this danger chimerical, because it has not yet been experienced in actual war, let me ask him to calculate what chance a ship would have for existence with a shell in her midst, con- taining fifty or eighty pounds of melted iron ? We must, for the future, rely mainly on vessels which from their relative smallness will be less likely than a line-of-battle ship to be struck by an enemy's shot, and at the same time will not, in the event of being struck, endanger so fearfully large an amount of life and property. We ought to improve our marine artillery to the utmost, in size, weight of metal, and everything that constitutes the efficiency of a gun ; and then not place more than one or two guns on board of each vessel. In a word, we must mainly rely on GUN-BOATS ; but on gun-boats probably equal in destructive power, though far inferior in ton- nage and in the number of the crew, to the seventy-fours of Nelson's time. The chief drawback on the efficiency of small ships of war, has been the impossibility of carrying fuel enough for long voyages; but recent improve- ments in the steam-engine will be found to overcome this by the enormous saving they effect in coals.

I believe there is not the slightest originality in these ideas ; but if they are of any value they cannot be too often discussed. Respectfully yours, J. J. M.