Mr. Chairman and Gentlemen:—
The progress of the past century is in no instance more marked than in the development of naval architecture. In this development—as in all kindred onward efforts—the advance has not been a steady one, but mingled with many retrograde steps, which at times have seemed to endanger the attainment of its object. That object I hold to be the construction of the most effective war vessel. By a careful study of the various means taken during the past to accomplish such a result the type of ship necessary to fight the battles of the future may be discovered. While leaving this broad subject to those whose talents and energies may have fitted them to deal with it, I propose to limit myself in the following pages to the history of armor as applied to naval vessels, and to briefly discuss the important lessons which it teaches.
The history of armor may be divided into three epochs.
I. The Theoretical, which extends from the first use of artillery on board ship (1350), to the year 1842, when Ericsson gave the world a screw-man-of-war, armed with a wrought iron gun.
II. The Experimental, which begins at this date, with the introduction of iron naval-ship-building, and ends with the first iron-clad engagement at Kinburn, in 1855.
III. The Practical, extending from 1855 to the present time.
I. I have termed this period the Theoretical; but I would not have it understood that no experiments took place prior to 1842. Attempts there certainly were to cover vessels with defensive plates, but these attempts as a rule began and ended in plans proposed by various inventors, and never resulted in the completion of a sea going armor clad.
The first authenticated propositions for metallic armor date no further back than the beginning of the present century, yet as a matter of curious research it may be of interest to look into the work of one Giacomo Bosio, published in 1612, where we shall find a description of the great karrack Santa Anna, a vessel of seventeen hundred tons, built at Nice in 1530 for the knights of St. John. She had six decks of which two were under water, all were sheathed with lead, and bolted with brass, which does not consume lead as iron does, and thus constructed it was impossible to sink her, although all the artillery of a fleet were fired against her. Her huge main-mast was made in pieces, and of such size six men could not embrace it. She was never pierced below the bulwarks. She was entirely sheathed with lead from the bulwarks downwards, and below the water line bolted with brass bolts." Then follows a description of ovens for baking fresh bread, of an armory for five hundred pieces, of forges for three master blacksmiths, and of many other novelties; showing that in naval architecture, as in all the other arts of war, the knights of Malta were far ahead of their day.
At the siege of Gibraltar, 1782, the French and Spaniards employed floating batteries made by covering the sides of ships with junk, raw hides, and timber. The largest of these vessels was fourteen hundred tons and carried a battery of thirty-two pdrs.
In 1813 Fulton constructed a floating battery for the United States government; and, as early as 1814, Thomas Gregg of Pennsylvania patented a "ball proof-vessel." Gregg's design embraced a flat upper deck, from which the sides and ends sloped outwardly to the water line, where the upper part of the vessel was very broad, overhanging the submerged portion, and protecting the rudder and means of propulsion. The gun deck was nearly level with the water line, and ports were cut in the inclined sides. She was to have been covered with copper or iron. About this time the elder Stevens began a series of experiments at Hoboken, New Jersey, which led him to the same conclusion regarding the merits of inclined sides.
During 1821, Colonel Paixhans recommended armor for ships as worthy the consideration of the French admiralty; while England tried the effects of shot against masonry covered with iron, at Woolwich, in 1827. India rubber was also proposed, as sheathing for a seventy-four-gun ship, but whether for the purpose of resisting shot or the action of sea water I am unable to discover. Eight years later a series of trials took place at Mentz against forged and rolled iron.
The United States, profiting by the foreign reports, experimented upon a laminated target of sixteen quarter inch plates; through which Commodore Kerry fired an eight inch shot at Sandy Hook, in 1837. This target, five feet high, and two feet nine inches broad may, I think, still be seen at the New York navy yard. The failure of this plate did not convince the naval committee of 1841 that four inches of iron was too thin to resist projectiles, and a contract for a vessel with that thickness of metal was given to R. L. & E. A. Stevens, on the 10th February, 1843. "When Commodore Stockton, the following year, demolished a four and one-half inch iron target with a two hundred and twenty-four pound shot, Stevens increased his armor over two inches in thickness; and a second contract was made. By the terms of this contract the Stevens Battery was to have a length of four hundred and twenty feet, a beam of fifty-four feet and a draft of twenty-six feet; she was to be fitted with water tight compartments, and armored to four feet below the water line. Her sloping sides were to be covered with 6.75 inches of iron, backed with fourteen inches of wood. Her beams were to be made of six inch wrought iron bars. Her guns were to fire en barbette, and to be loaded below decks. That this vessel was never completed was no fault of her original designer; and in the disputes which followed between the contractors and the government the fact was forgotten that Stevens, as well as Gregg, gave to America designs for armored ships, containing the germs of almost all the systems which have since been claimed as original by foreign constructors.
For twenty years prior to this time another great brain had been at work, evolving many inventions. Prominent among them were two which were brought into practical operation, during the year 1842, in one vessel; and when the U.S.S. Princeton, propelled by Ericsson's screw, and armed with Ericsson's wrought iron gun was launched the war between armor and projectiles began. Heretofore the means of propulsion by steam had been by machinery entirely above the water, and exposed to an enemy's fire; the screw did away with this great drawback, removing the working beam and paddle, compact engines in the hull, giving motion to a propeller protected in part by the element in which it acted. The center of gravity was also lowered, and, the paddle boxes being removed, there was less surface to armor, and less target to hit. We now come to the
II. or Experimental Period. The Princeton was in reality Ericsson's first monitor, giving a warning, on both sides of the Atlantic, of the changes that were to ensue. Congress resounded with eulogies of the genius which would enable us in the near future to defy the navies of Europe. Parliament, perceiving the error the admiralty had made in driving the Swedish inventor from England, voted large sums of money to build trial propellers and built-up guns. The British foundries were ready for the emergency; stimulated by the success of their first iron steamers, they hastened to increase their plant so as to include the fabrication of armor plates for iron men-of-war. The age of iron had begun. Fairbairn and Lord Ross were standing sponsors for infant plates of three and four inches, which others vainly strove to kill with heroic doses of thirty-two pound shot. Rival metals were also asserting their claims as a means of defense, and General Totten writes in 1853 that, "next to wrought iron lead concrete proved the best material, as it will not crack nor splinter, heavy shot molding for themselves a symmetrical bed in which they are found crushed; their effect being local." The increase in the caliber of the new guns, and the consequent necessity for a thicker metal for a ship's defense, rendered the use of lead impossible; while the four and one-half inch iron plates, experimented upon at Portsmouth in 1850, still resisted the sixty-eight pound shot.
Four years later the Emperor Napoleon received a letter from Ericsson presenting a plan for a novel vessel; but even scientific France was not ready to adopt the radical changes suggested by the inventor, and the ''cupola ship" was kept for that March day of 1862, when the world was forced to acknowledge the value of a "vessel with armored sides protected against shot by being submerged in the water, thus securing buoyancy and protection at once." Reference to Ericsson's contributions to the Centennial Exhibition will show that his design of 1854: was in all essentials similar to the later Monitor of 1861, and that the turret was something more than a stationary shield or cupola; one of the main features being the concentration of the battery. I am thus particular in enumerating its distinctive characteristics, for, in the following year Captain Coles of the English navy proposed mounting a number of conical cupolas on the deck of a high sided, rigged ship, of the usual form, and even as late as 1862 he sent a model to the great exhibition with five cupolas. During those seven years—from 1855 to 18G2—Coles wrote many articles and lectures on the merits of his system, in none of which can I find any allusion to the name of Ericsson, perhaps for the reason that he saw the many differences between their two plans. Captain Coles' sad fate would naturally lead us to overlook any omission to acknowledge Ericsson's previous invention were it not for the fact that his friends have claimed that the cupola and monitor turret were identical. Besides there was a man in the United States who, eleven years before, had placed drawings in the patent office, of ''Timby's turret," and his right of invention was long after recognized by the government.
The Crimean war was now calling forth all the energies of the Allied Nations. France, especially, was busy constructing floating batteries covered with four and one half-inch plates. The hulls of these vessels were of wood; and the iron plates three feet long, and twenty inches wide. On the 17th of October, 1855, they received the Are of the Russian forts at Kinburn. The following particulars are from Commander Dahlgren's account of the action:—''The French floating batteries Devastation, Lave, and Tonnante, steamed in to make their first essay, anchoring some six or seven hundred yards off the S.E. bastion of fort Kinburn. The Russians could only reply with eighty cannon and mortars, and no heavier guns than thirty-two pounders, while many were lower. This was the sole occasion in which the floating batteries had an opportunity of proving their endurance. They were hulled repeatedly by shot, and one of them—the Devastation—it is said sixty-seven times, without any other effect on the stout iron plates than to dent them at the most one and a half inches; still there were ten men killed and wounded in this battery by shot and shell that entered the ports."
This first engagement of ironclad vessels ended the experimental era. The immense advantage derived from an armor-shield was established by the rough ordeal of war. It was useless to argue that the ordnance brought to bear against the batteries was of small caliber, for heretofore it had always been held that guns of inferior dimensions, planted firmly on land, were more than a match for much larger ones mounted upon a floating, unsteady platform.
Two other facts went far about this time to convince the naval world of the necessity of providing against the destructive effects of shell firing. One was the annihilation of the Turkish fleet at Sinope in 1853; the other the arrival of the United States frigate Merrimac, on the Mediterranean station, with her tremendous battery of IX inch Dahlgren guns. Shells were beginning to be used as mines instead of missiles; it became essential to find some material stronger than wood to keep them from entering the ship. The three French batteries of Crimean fame were not equal to the task; and their five English imitations were too unwieldy to accomplish the result. Let us see how the emergency was met in the
III. Or Practical Period. Thus far I have treated the subject historically, merely dwelling upon certain points calculated to illustrate the important part played by America and France in the earlier development of armor. To follow the successive steps of this development from the year 1855 to the present date would encumber these pages with a mass of detail that might confuse the thought and take from the object in view. I will therefore give as short an account as possible of the different causes which have led to the perfection now attained in the application of iron to men-of-war, and then divide the armorclads of all nations into five systems, showing the results attained in each.
Between the years 1855 and 1879 extraordinary activity has been displayed in naval science and maritime art. As early as 1859 Thorneycroft endeavored to do away with rivets and bolts by making tongued and grooved bars; and Russia experimented against steel plates four inches thick, with sixty-eight pound shot. The inventive talent of the United States was animated by the breaking out of the civil war—Knight, in his mechanical dictionary, mentioning fourteen patents that were granted for armor during the first three years of the Rebellion. Wire, rubber, millboard, chain-cables, papier-mâché, cotton, hay, and logs of wood were proposed; some of these were put to the tests of experiment, and even actual engagement, but none were received with favor, while all were considered as makeshifts.
Wrought iron now began to be handled in greater masses than had ever before been deemed practicable, tremendous hammers and rollers, making heavier and heavier plates, were constructed until in 1867 the Atlas works succeeded, by means of Sir John Brown's carbonizing process, in producing a solid mass of iron fifteen inches thick, twenty feet long, and four feet wide. Bessemer, Siemen, Martin, and Whitworth manufactured steel, by new methods, nearly as cheap as iron. Krupp showed how breech-loaders would reduce the size of turrets, and Armstrong replied that hydraulic machinery would accomplish a like result for his muzzle-loading guns. Naval architects lessened the weight of ships by novel systems of framing and made double hulls to resist rocks and torpedoes. In 1861 Coles was at work on his shields and Eads on his fixed turrets. During 1858-9 Elder wrote lectures upon his circular batteries, and Hyde discussed his scheme for double-deflecting armor, while three years before Austria had given Italy and the world a lesson at Lissa on the value of the ram and end-on attack. In July 1872, the English, lacking a foreign foe, cannonaded the Glatton's turret with the Hotspur's 25 ton gun. Soon after this date experiments were made as to the relative merits of iron and steel for armor, from which two facts were unexpectedly evolved; one, that a steel plate, of given thickness, might keep a certain projectile from piercing it even though the shot shattered the plate; whereas, when covered with wrought iron, the shot penetrated both iron and steel. The other, that a shot might pierce a plate of given thickness, but would fail to penetrate two of half that thickness, separated by an air space. In 1873 the German government submitted the Gruson dome-shaped turrets to severe tests; these turrets were made of iron east in chill-molds, and united to one another by tongues and grooves. In 1876, the Spezia trials of the 100-ton gun proved the fallacy of many preconceived ideas concerning the value of steel and iron targets, and, besides inciting Sir John Brown to make a twenty-six inch plate, again brought out the inexhaustible powers of English foundries in the Wilson compound plates, (Fig. 1. Plate IV.) and the Whitworth combination of soft and hard steel.
Coincident with the changes and improvements in armor, during the past twenty-four years, is the growth of the gun and its projectile. We left the weight of shot in 1855 less than one hundred pounds, we find it, in 1879, increased to over two thousand. The power of resistance has only followed the means of offense. Above all the secondary reasons mentioned stands out, therefore, the one great cause which has produced the floating citadels of to day—the continued rivalry between artillery and armor.
We will now consider the various types of armorclads. Although many vessels may be a combination of two or more of the following systems, we can in general classify the armored fleets of the world under five heads.
I. The Vertical or Broadside System.
II. The Turret System.
III. The Deflecting System.
IV. The Circular System.
V. The Ram System.
I. The Vertical System. The principle involved in this method of applying armor is the oldest of all, being the one naturally suggested to the human mind centuries ago. A shot is to be resisted, therefore increase the effectiveness of the bulwark, by adding to its thickness, or placing upon the ship's side a better defensive medium. This system also permitted the old type of vessel to be utilized, and new ones of similar proportions to be built; thus economizing the material already on hand, and catering to the proverbial conservatism of governments.
The vertical system is identical with the broadside. That it has been extremely tenacious of life may be seen by the perfection to which it has been carried abroad. America has never appreciated its merits. Our first iron-clad was a turret ship, and seeing that the monitors were superior to any corresponding type of other navies, we clung to that system, taught by the experience of former years that "in the one superior class" was our strength.
The only vertically armored broadside ship ever built in the United States was the New Ironsides, completed at Philadelphia in 1862. She was two hundred and forty feet long and had fifty-eight feet beam. Her armor was composed of four and one-half inch solid plates. She carried sixteen Xl-inch guns and two 200-pdrs. She was burned at Philadelphia in 1865.
Returning to foreign dock yards, we find France, in 1858, already at work on a broadside iron-clad. The keel of La Gloire is laid, and England follows with the Warrior; vessels of widely different types, but both covered with four and one-half inch plates. The Warrior, on account of her extreme length, was only partially armored, while La Gloire was completely protected. The Warrior's iron hull was a step in advance of La Gloire's wooden frame, but the French frigate had the handiness of a shorter ship, the smooth sides, peculiar bow, and reduced canvas essential to the requirements of the times. That the English recognized the French model as correct in the main is shown by the Prince Consort, a vessel very similar to La Gloire begun three years after.
Before 1863 the keels of several vessels four hundred feet in length had been laid, but this class proved unwieldy though possessing sufficient flotation to be completely armored. Then came the era of short ships, and, the destructive effect of ordnance increasing, buoyancy had to be given by additional beam; all-round fire next became essential, and decks and encumbrances were removed, wherever they interfered with the guns. Still the plates grew thicker, and lest the armor should become too heavy to be floated, all the parts above water were left free to be shot away, except those necessary for the battery, the guns being placed in a central casemate, where they could be fired in single or double tiers. It will be seen by the foregoing remarks that I refer to the series of ironclads, which, beginning with the Warrior, includes the Minataur, Hector, Bellerophon, Hercules, Sultan, Audacious, and ends with the Alexandra—a vessel of such completeness that it is safe to say she is the perfection of the system of which we are treating.
France having expended large sums in her short sighted policy of repeating vessels of each class, and crippled by her war with Germany, has lost the prestige gained by her original departure from preconceived ideas of naval construction, but the Republic is observing critically, imitating successfully, the Devastation—carrying a heavier broadside than any armor-clad afloat—being the latest result. England has ranged far ahead of her rival, both in novelty of design and form of hull, and the contrast between the navies of the two countries would be especially noticeable to one who might have the opportunity to see their fleets anchored side by side. The French frigates are covered with projecting surfaces, davits, cat heads, and bumpkins, while the smooth rounded sides of Her Majesty's ships are free from all encumbrances.
Germany, while deserving all praise for the energetic and practical manner in which she has increased her navy, gives us no new type, of armor-clad, her vessels having been built in England and France, or from plans borrowed from those countries.
It is scarcely necessary to allude to the other Powers, as they have presented no new varieties of the broadside system; though an exception may be made in favor of Austria, the armor of her casemated Tegethoff and Custozza being attached so as to lessen the weakness caused to heavy plates by extreme curvature.
The Alexandra [Plate II,] therefore remains the exponent of the best class of a vertical sided armor-clad. King gives the following particulars concerning her:—"This vessel, the largest masted ironclad
heretofore designed, is a central-battery ship in the best sense—that is, she needs no bow nor stern batteries to give her end-on fire. For the first time a broadside armored masted ship is built with satisfactory all-round fire, for, out of twelve guns, four of them, including the heaviest, can fire straight ahead and two straight astern. On each broadside from four to six guns can be fought according to the bearing of the enemy. In other words, she has almost as perfect an all-round fire as is attainable in a broadside armored vessel, and this forms her chief claim to consideration. So far as the fighting portion of the vessel is concerned, she is a two-decker. The battery consists of two Woolwich rifled muzzle-loading guns of twenty-five tons each, and ten of the same kind but of eighteen tons each, the former being a size not previously attempted to be carried on a broadside-ship. The two 25-ton guns are located in the upper battery forward. These can be trained from 2° or 3° across the fore-and-aft line forward to several degrees abaft the beam. Two 18-ton guns have much the same training aft that the others possess forward. These four guns comprise the armament of the upper battery. To localize the effects of shells exploding between decks, the main-deck battery is divided by an armored bulkhead which forms a continuation downward of the forward bulkhead of the upper battery. In the portion which lies under, and corresponds with the upper battery, are six 18-ton guns, three on each side, for broadside fire only. In the forward and detached portion of the main battery are two other 18-ton guns for end-on fire, which they attain by means analogous to those employed to give similar fire to the upper-battery guns. Forward of the main deck battery the whole side of the ship is set back from the level of the main deck (at the top of the armor-belt) upward. In other words, the ship forward of the battery is narrower above the main deck than below it; Four guns can therefore fire right ahead past the sides. Their arc of training is nearly 100°. The sills of the main deck ports are nine feet, and those of the upper deck ports more than seventeen feet above the water. The water-line is protected by a belt having a maximum thickness of twelve inches and the armor forward is carried down over the ram, both to strengthen the latter and to guard the vital parts of the ship from injury by a raking fire from ahead, at times when waves or pitching action might expose the bow. The machinery, magazines, et cetera, are similarly protected against a raking fire from aft by an armor bulkhead, five inches thick. The batteries tire protected by armor only eight inches thick below and six inches above, which is a deficiency of protection against guns now in use on board armed vessels in European navies."
The Turret System. This system of applying armor is not, as its name would imply, simply the mounting of a turret upon the deck of a vessel, as a shield for the battery and gunners. It includes concentration of guns in a small space, thereby bringing them more completely under control, enabling fire to be delivered in all directions, and affording the best defensive covering. We thus gain a few large guns instead of numerous small ones, and with a given flotation required for the ship can transfer the armor, which would otherwise be needed for the broadside, to the water-line.
A turret vessel may therefore be defined as an armor-clad of low free board, carrying a few large caliber guns capable of all-round fire from a revolving, armored turret.
The Monitor was such a vessel, presenting all the characteristics mentioned above, while the turret ships proposed by Eads and Coles were not; Eads' "armor clad central battery" having a fixed turret, and Coles' "cupola ship" lacking the feature of concentration so essential for the fulfillment of the theory.
The success of the turret system at Newport News led to the building of a great number of monitors, and before the close of the Rebellion the United States possessed a fleet of fifty-four vessels of this class; the most powerful being the Dictator, and all capable of defending our harbors against any foreign foe. Many minor defects in the original had been removed; but a few faulty details were allowed to remain, to which I would call attention as they seem likely to be perpetuated in the new monitors now building upon the Delaware. The means of egress from the hull is mainly from hatchways that can never be used in a seaway. By the addition of a low breastwork around the turret, extending to the port sills, the liability to jam the revolving gear would be lessened, and the crew, in any sudden emergency, would have an additional means of escape at sea from hatchways within the breastwork. These hatchways could also be kept open in moderate weather to admit light and air. The arrangement of the deck steering gear is also bad and the manner of loading, both antiquated and slow.
Although England placed little confidence in the turret system at first, a mongrel vessel, combining the advantage of low freeboard and the disadvantages of lofty masts and heavy top hamper, was constructed after plans suggested by Captain Coles. She was christened the Captain, armored with from six to ten-inch plates, and capsized on her trial trip September 6th, 1870.
The Monarch was a more successful vessel; but the advantage obtained by her revolving turrets is partially counter-balanced by the retention of masts, and the freeboard of fourteen feet presented to the fire of an enemy. Neither of these ships therefore fulfill all the requirements of the turret system.
In 1864 the English cut down the Royal Sovereign, covered her with five and one-half inch plates, and placed four turrets, containing four nine-inch gnus, upon the former three decker. The Scorpion, with two turrets was also launched about this time; but it was not until after the Miantonomoh's voyage to Europe that the coast defense monitors were begun, and Ericsson's type imitated, to be in many instances developed into a better vessel. Solid plates immediately took the place of laminated, the glacis and breastwork were added, the thickness of armor was gradually increased to twenty-four inches, iron hulls were substituted for wooden, wood backing was used in the turrets, behind which came an inner skin and a mantlet to protect the gunners from flying rivets and bolts. The decks were armored horizontally and a ram-bow in many cases added.
It would carry this paper far beyond its limits to refer to the peculiarities of each class, or, properly speaking, of each vessel, but the distinctive features of the twenty odd turret vessels of the English navy may be easily obtained from the standard authorities. If the sequence be followed from the Cerberus (built for colonial defense in 1868) through the Fury (1870), Glatton (1870), Gorgon (1871), Devastation (1871), Dreadnought (1877) to the Inflexible (1879) it would be seen how far these ships have departed from the original model; though maintaining, under the ever changing relations between offense and defense, the cardinal points of the turret system.
We have noted, when treating of the vertical system, how the increase in the weight of armor has gradually stripped it from the high sides of the frigate until casemate and water line alone were protected; now, although turrets by their reduced size and rounded exterior, give a less weight of armor than the casemate, the limit of buoyancy has been reached even with them; and we find in the Inflexible, an armor-clad so widely differing from Ericsson's Monitor that the "citadel ship" may be said to represent an entirely novel system. Mr. Barnaby, her designer, gives us the following description:—
"Imagine a floating castle one hundred and ten feet long and seventy-five feet wide, rising ten feet out of water, and having above that again two round turrets, planted diagonally at its opposite corners. Imagine this castle and its turrets to be heavily plated with armor, and that each turret has two guns of about eighty tons each. Conceive these guns to be capable of firing, all four together, at an enemy ahead, astern, or on either beam, and in pairs toward every point of the compass. Attached to this rectangular armored castle, but completely submerged, every part being six to seven feet under water, there is a hull of ordinary form with a powerful ram bow, with twin screws and a submerged rudder and helm. This compound structure is the fighting part of the ship. Seaworthiness, speed and shapeliness would be wanting in such a structure if it had no addition to it; there is therefore an unarmored structure lying above the submerged ship and connected with it, both before and aft the armored castle, and as this structure rises twenty feet out of water from stem to stern without depriving the guns of that command of the horizon already described, and as it moreover renders a flying deck unnecessary, it gets over the objections which have been raised against the low free board and other features in the Devastation, Thunderer and Dreadnought. These structures furnish also most luxurious accommodations for officers and seamen. The step in advance has therefore been from fourteen inches of armor to twenty-four inches; from thirty-five ton guns to eighty tons; from two guns ahead to four guns ahead; and from a height of ten feet for working the anchors to twenty feet. And this is done without an increase in cost, and with a reduction of nearly three feet in draught of water."
Italy has gone a step further in the construction of floating castles, and intends to defy the world with her diagonally turreted Duilio and Dandolo, plated with solid steel armor, twenty-two inches thick. Even with these monsters she is not content, but lays the keels of the Italia and Lepanto, stupendous floating batteries four hundred feet long, with oval, armored redoubts to enclose turrets of some extraordinary thickness, to be determined by future experiment.
Rumors are already bruited about that the Duilio will not float her heavy armor, and until the Italia and Lepanto are launched we must hold with the British director of naval construction that, in the Inflexible, we have reached the extreme limit in thickness of armor for sea going vessels.
The other Continental Powers have been imitators of the American and English turret ships. Russia has a Devastation in her Peter-The-Great, Germany, a Monarch in the Preussen, Austria, monitors in
the Maros and Leitha, France has steadily set her face against the system, her whole navy list containing the names of only two turret vessels in actual service—the Unandaga and the Cerbere.
III. The Deflecting System. The plan of lessening the chance of penetration, by placing the armor at an angle to the vertical, was both originated and developed in this country Gregg and Stevens proposed deflecting armor in the earlier part of the century, Tees and Caudwell made complete models of ironclads with inclined sides nearly twenty years ago; while the first vessels built on this principle were used on both sides during the Rebellion. The Merrimac was an example of the type, and the gun-boats of the De Kalb class embodied the same idea. Before the close of our war there were numerous craft of this description afloat on our western rivers, with plating varying from four inches to three-fourths of an inch. Even the latter, though termed ironically "tin clads", did excellent service. The most powerful vessel of this description was the Dunderberg, built by Webb—her solid plates varied from four and one half to three and one-half inches in thickness. She was sold to France and re-named the Rochambeau.
Hotchkiss, about 1862, invented an ingenious method of attaching over-lapping plates, after the manner of shingles. The efficiency of the inclined side was thereby increased, and a shot finally thrown back into the water. An English engineer, named Hyde, elaborated the system spoken of before the United Service Institution in 1869. His armor was to be attached to a hull of such shape that a shot striking either above or below water would be received at a very acute angle. The arguments used in favor of this double deflecting system were the great resistance offered to penetration, the protection afforded in a sea way, and that the hues of a vessel to which such plates had to be attached would give more stability than those of a ship with vertical sides. Captain Palmer of H.M.S. Magdala has also proved that inclined armor is two and one-fourth times as effective as vertical of the same weight.
Of late years the deflecting system is again receiving its share of attention, the Engineer remarking, in 1876, that, "since the Spezia experiments, there are but two possible chances for the plate, and these will be found in so disposing it that the shot may strike it at an angle, and in using air spaces." Combined with the deflecting surfaces presented by turrets this system may therefore become one of importance; and we may in the future see improved Merrimacs and Tennessees as we have already witnessed perfected Monitors and Warriors.
IV. The Circular System. The advantage of this system lies in the immense flotative power given by the shape of the hull, and the consequent ability to carry heavy armor. The merit of having proposed a circular iron-clad is due to Elder, an Englishman, who, in 1868, described the system in all its details, giving plans of a vessel which, in essentials, was identical with the later Russian Popoffkas. "There may,"—as Mr. Reed said in his lecture before the United Service Institution, "be old books that contain engravings showing such a ship filled with armed men;" but neither Mr. Reed nor any one else has ever been able to name those books. Admiral Popoff may be credited—as the lecturer further infers—with being the man to call circular ironclads into existence, but it is the credit that should be given to one who, through unlimited means and power, has been able to give practical effect to the inventor's theoretical proposals. The first of these vessels was launched at Nicolaief, southern Russia, in the spring of 1873. She was called the Novgorod, and was followed by the Admiral Popoff. These ships are alike in principle, the Admiral Popoff having an extreme diameter twenty-one feet greater than the Novgorod. The latter is completely circular at the water line, with the exception of a small protuberance at the stern for the steering apparatus; the bottom is flat and has twelve keels attached to it parallel to one another, and at equal distances apart. The diameter is 101 feet just above water, and 76 at the flat bottom. The deck slopes from a central height of five feet to less than two at the circumference. Coinciding with the centre is a fixed tower carrying two eleven-inch B. L. guns. The top of the tower is only seven feet above the deck. The displacement of the ship is 2491 tons. The armor consists of two lasers, an inner one, of unusual form, consisting of corrugated iron beams seven inches deep and one and a half inches thick, connected to the skin of the ship. The outer plates are in two tiers, the upper nine inches, and the lower seven inches thick. The turret armor is nine inches, backed with teak of same thickness; within this is an iron skin. Two feet of timber cover the armor at the water line. The bottom is double, and the hull divided into thirty-six compartments. The dimensions of the Admiral Popoff are proportionally greater, and she was the first vessel ever floated with plates equivalent to eighteen inches.
I have gone into more particulars concerning these vessels than their merits seem to justify, from the fact that at the time of their launch great importance was attached to the event—the ex-chief constructor of the royal navy deeming the Popoffkas worthy to be compared with England's ironclads. The low speed obtained by the circular ships, their complicated machinery for driving the six propellers, the large horizontal target they present to an enemy, and their low towers—from which the guns are to be fired, en barbette—are all radical defects in the system, which prevent it from ever assuming an important position in naval warfare.
The Popoffkas were never heard from during the late Eastern war, though constructed with a special view to operations on the Black Sea; and it is an open question whether the "turret citadels," for harbor defense, proposed by Timby, many years ago, and which could have been towed from port to port faster than the Novgorod can steam, were not better adapted for coast defense.
V. The Ram System. The history of rams begins long before the Christian era. The Persians taught the Greeks how to use the ram at Salamis and Actium, and, 480 B. C, Queen Artemesia initiated the practice of running down a friendly vessel, but with a more laudable object than has been lately done by modern armorclads. Then, as now, the ram successively changed its form from the overhanging to the straight, and the under water projection, and tactics were modified to suit the alterations in the type of vessel. It is beyond my province, however, to treat of this subject, which belongs more to the development of ships than to the application of armor; for plates may be fastened to a ship fitted with a ram-bow in the same way that they are to other vessels.
James Nasmyth advocated the steam ram as long ago as 1836, and almost all modern ironclads have been supplied with this means of offense. No modern vessel, it must be admitted, presents the proper qualifications, and when we come to the discussion of the ram of the future the question offers features which materially modify the present methods of applying armor. The true ram must present the minimum amount of surface to horizontal and plunging fire; need have no offensive armament save her snout and torpedoes; and no defensive guns except such as are necessary to free her deck from boarders. The thickness of her armor can therefore be greater than that for any other type of vessel. Such a craft was suggested by the cigar shaped boats of our war, and has resulted, in England, in the Sartorius Ram. In this vessel convex steel plates, fastened in a novel manner to the small portion of the hull above water, are to be united to a steel frame armored with heavy plates. In this country, the ram has been carried to a great degree of perfection by Admiral Ammen, but the lack of appropriations has prevented his plan from being supplemented by an actual vessel, and England will undoubtedly have the first genuine ram afloat, though its design will embody features long since advocated by the ex-chief of our Bureau of Navigation.
Several methods of fitting armor have come into use, that do not strictly belong to any of the foregoing systems.
I. The Barbette System, so persistently used by the French. It includes the plan of a fixed tower, over which the guns fire. The arguments used in favor of this system are that the tower being lower than the revolving turret its weight is diminished; that an enemy can be clearly seen; and that the morale of the gunners is better assured than in an enclosed battery.
II. A combination of barbettes and rounded projecting casemates. Several vessels of the French navy are constructed on this principle, the towers being placed near the ship's side.
III. A system similar to the above, except that the towers are placed at bow and stern, a casemate containing two tiers of guns being added amidships. The English Temeraire (Plate II.) is an armor-clad of this description.
IV. The Belt System. The English authorities, frankly acknowledging the impossibility of protecting both guns and hull, have, in the Shannon, (Plate II.), abandoned battery armor, and limited the plates to a belt nine inches thick, extending from a vertical armored bulkhead at the stern to a similar one sixty feet from the bow. These bulkheads are a protection from fore and aft fire, and the crew are to run the chance of being struck by shells delivered above the belt; the alternative being that they would probably be wounded first and drowned afterward, if the weight of armor were distributed over a greater surface.
V. Torpedo Vessels. The armor for torpedo boats has thus far been a simple mantlet to protect their crews from small arms and gatlings. The revolving guns of heavier caliber, now coming into use, may necessitate a thicker plating, but this class of vessel must always depend upon celerity of movement rather than upon shot proof covering.
The analogy between the history of personal and ship-armor has forcibly presented itself to my mind while writing the preceding pages. If we follow the comparison through its various steps it will be noticed that the knight of the earlier centuries was clad in all sufficient plate, even as the first iron-clad was encased in complete armor; plate and armor growing thicker and heavier as projectiles became more powerful. In both cases, the limit of weight being reached, recourse was had to deflecting systems, subsequently rendered less vulnerable by padded coat or wooden backing. In our own century the helmet of the dragoon and the cuirass of the guards still lingered, furnishing prototypes of the Inflexible class, the vital points alone protected. Before the deadly weapons of the past decade the soldier throws aside all defensive covering and becomes the light mobile skirmisher of recent wars. Whether we are to follow the sequence to such a finality is a question which, though logically correct, is still open to dispute.
That the days of armor-clads built on the vertical system are numbered most of us will admit, the latest argument against them being that every point of the target, presented by their high freeboard, becomes a fuse. In other words the heat developed by a large caliber rifle shell passing through armor-plate is sufficient to explode it within the ship, among a crew pent up in a contracted casemate. Were the same projectile to strike a wooden vessel it would pass completely through her, bursting beyond and leaving a hole possible to plug.
Like arguments may undoubtedly be used to the disadvantage of the turret system, but the monitors present such a small surface, that it is still questionable whether recent monster guns, though possessing sufficient power to pierce any plate, can be practically worked against them.
The destructive effect of the ram has been so thoroughly proved, its power to carry heavy plates so completely demonstrated, that armor will be carried on this class of vessel long after it is stripped from other ships.
Rams built after the design proposed by Admiral Ammen would cost comparatively little, and one in each of our harbors, supported by monitors and torpedo boats, might successfully resist the largest ironclads.
We are next to decide upon the kind of armor necessary for our rams and monitors. The experiments in Germany with the Gruson dome shaped castings, chilled on the outside and slowly cooled on the interior, have proved that cast iron may be made into a much better plate than has heretofore been deemed practicable. Still I am inclined to believe that cast iron will never be strong enough for the purpose, and that its lack of malleability will prevent it from ever being used for the curved surfaces of a ship's side.
Wrought iron possesses many requisites upon which it is not necessary to dwell, but the very advantages which render it a desirable metal to work into shape and easy to fasten to the frame of a vessel make it penetrable by rifled projectiles.
Steel, while possessing many of the characteristics of wrought and cast-iron, has the additional quality of hardness, which gives it a great superiority over both for the purposes of which we are treating. Low steel, though not as hard as high, has much more tenacity, and would seem to be the variety necessary for our use. But steel, though hard enough to resist the blow of the largest caliber projectile, is liable, after being struck, to crack, become loose, and ultimately to detach itself from the backing. To remedy these defects, it has been proposed in England to make the body of the plates of wrought iron, and the exposed surface of steel. These plates (Fig. 1), called the Wilson compound armor, are made as follows;—"The wrought iron is introduced (horizontally) into a furnace of peculiar construction, and when it has arrived at a welding heat, the melted steel is run in on top of it. The damper is then closed, and the crown of the furnace removed, a chilling plate being put on top of the steel; or the refractory bed and sides containing the steel and wrought iron may be removed on a 'bogie' and cooled outside."
Whitworth proposes to make the body of the armor of very soft steel, and to plug it with the hard steel bolts—these bolts to receive the force of impact. The Italians are also making experiments with steel bricks twenty-two inches thick, set in wrought iron cells.
The results obtained from these various plates go to prove their great superiority over all others. Two points, developed by the tests applied to the Wilson compound armor, demand attention, viz.—that the union between the steel and wrought iron was not injured, and that the outer casing of steel, though cracked by the large shot used against it, still held on to the backing. By way of making these plates still stronger it has been proposed to pour the melted steel over a corrugated wrought iron plate, (Fig. 3) thus making the junction between the metals more firm. To localize the cracks the steel is to be separated by small intervals (Fig. 2) or the exterior of the plate is to be made of alternate layers of iron and steel. (Fig. 4.) These facts naturally lead us to the conclusion that the armor of the future will be a combination of steel and iron in some form.
Steel is now being made remarkably cheap in this country by the Bessemer, Siemen, and Pernot processes, and the want of heavy hammers and rolling mills can be neutralized by the decreased thickness of the wrought iron demanded for the compound plates.
In this connection I would suggest that the Hotchkiss Armor (Fig. 5) might be utilized. The projecting edges, instead of being put on in layers, to be fused to a wrought iron backing. Again a deflecting system, like the Hotchkiss, gives us ample room for a water or air space between a double line of armor, an advantage to which I have already alluded.
I find myself digressing, Mr. Chairman, into a field which is not covered by the title of the lecture, and will not further tax your patience with a recital of my views of the future man-of-war. The needs
of the service in that direction will undoubtedly be thoroughly discussed in our next Prize Essay.
A word of explanation and I am done. The preceding pages were prepared to supply a want which I discovered while endeavoring to obtain a few details in regard to armor. The subject is scattered over so many works and periodicals that much time was lost in consulting numerous volumes which contained little or no information. In order to aid the student I have endeavored to condense the main features of the History of Armor, and by way of further assistance, in the same direction, will add at the end of this lecture a list of the standard authorities from which my notes have been taken.
1. Engineering—Vols. 4, 5, 6, 7, 9, 12, 13, 14, 15, 17, 18, 19,21, 27.
2. Engineer—Vols. 32, 33, 35, 36, 40, 41, 42, 43, 44, 45.
3. Holley—Ordnance and Armor.
4. Spon's—Dictionary of Engineering.
5. Knight's American Mechanical Dictionary.
6. Journal Royal U. S. Institution—Vols. 2, 4, 6, 7, 8, 11, 12, 16, 17.
7. King—Report on European Ships of War.
8. Report of Secretary of the Navy 1864.
9. Scribner's Magazine, April 1879.
10. Haydn's Dictionary of Dates.
11. Johnson's cyclopedia, art. ships, iron-clads.
12. Elgar's, Ships of the Royal Navy.
13. Ericsson's, Contributions to the centennial exhibition.
14. Appleton's Am. annual cyclopedia 18G4, p. 720.
15. Dahlgren's Report of the Kinburn engagement.
16. Armor Plating etc., Major King, 1870.
17. The Steven's Battery—Memorial to Congress, 18G2.
DISCUSSION.
Lieut. Brown. In regard to what Lieut. Miller states about rams I would remark that there is little difference between that; Alarm and the ram suggested by Admiral Ammen. They were both designed for this purpose by distinguished officers, and were modeled, I think, by the same constructor.
The Alarm is designed to strike ten feet below the water, whereas the ram proposed by Admiral Ammen is to strike but two feet below the surface. Owing to the plan of carrying armor so far below water which now seems to be coming into favor, I think ten feet the better. A ram running well ahead affords stability for armor and guns on the bows. Numerous water-tight bulkheads with doors self closing when the compartment commences to fill, would prevent the ship from sinking forward when the ram was injured.
The ram proposed by Admiral Ammen is to be a turtle back with armor three inches thick. I think with armor on bows as on Alarm the same invulnerability can be obtained. Of course it will be necessary to light the vessel having armor like the Alarm bows-on but that is the natural way to fight a ram. The Ammen ram has two screws to drive her thirteen knots. The Alarm has not yet equaled that speed but it is undoubtedly a fact that vessels of her model can be driven that fast.
The general plan of hull of these vessels is the same—both built on the transverse bracket system with two skins and heavy longitudinal frames. The ram is two hundred and five feet long, thirty feet wide and thirteen feet draft, while the Alarm is one hundred .and seventy-three feet long twenty-seven feet wide and ten feet draft. The skeg of the Mallory propeller will, however, increase her draft. The blow delivered by either would be ample to destroy any ironclad. I can see no advantage in building vessels as large as the proposed ram and having no bow gun on them.
Lieut. Stockton. It has seemed to me that Lieut. Miller in giving the entire preference to the turret system, has only considered one side of the case in relation to the broadside system, and that is the defensive. It appears to me that when the vessel is acting on the aggressive, the broadside vessel has advantages over the turret ironclad; more particularly while attacking shore batteries and forts. I would like to hear from those officers who witnessed the New Ironsides and monitors attack the shore fortifications before Charleston. I know of no recent engagement where a combined force of broadside and turret vessels made an attack on works on shore.
Commander Cotton. It was a noticeable fact, in the various attacks of the ironclad squadron upon the earth and sand works before Charleston, that the New Ironsides, with her broadside, which was composed of seven XI in. guns and one 200 Parrott rifle, could silence the fire of batteries Wagner and Gregg with comparative ease; whereas, when these works were engaged by several monitors, whose united number of guns equaled or exceeded, and whose weight of metal exceeded the broadside of the Ironsides, the batteries were not only not silenced, but they briskly returned the fire of the monitors.
Civil Engineer Prindle. I was attached to one of our gun-boats during the operations before Charleston, alluded to by Commander Cotton, and can fully corroborate his statement. I often saw the whole monitor fleet engage those batteries for several hours at a time, and often supplemented by the gun-boats, having larger Parrott rifles, at long range, with the enemy returning gun for gun through the entire action. The monitors would then be withdrawn and the New Ironsides, with her broadside battery, go into action and speedily silence the enemy's tire alone.
Lieut. Stockton. Although experience shows to a certain extent that a broadside iron-clad cannot be entirely armored, still if the ship floats she can be of the greatest service, and perform certain work that a turret vessel cannot; hence I think a belt line of armor at the water line will keep her afloat and in a state of high efficiency. Not that I consider a broadside iron-clad the typical vessel, but that she can accomplish certain highly important work better than any other class extant.
Lieut. Miller. In the space at my disposal it was impossible for me to go deeply into the subject of torpedo vessels, and whether rightly or wrongly the Alarm has always been classed under that head. She undoubtedly has a ram, but she also has a gun and torpedoes, and these two additional modes of offense seem to me to destroy her distinctive feature as a ram. Lieutenant Brown has lately given us a very able and complete description of the vessel he commands. I trust he will shortly supplement it by an account of how he would tight her against an iron-clad. How is he always to keep bows on? When fire his gun? When ignite his torpedoes? It will take a cool head to decide three such vital points at a moment when one's whole force should be concentrated upon striking the enemy at a given point. The forty-five thousand pounds of the XV inch gun and carriage would I think be much more advantageously disposed as armor for her exposed parts, while in the crash of contact with the enemy the torpedoes are as liable to inflict injury on the ram as on the rammed.
In regard to the remarks of Lieut. Stockton, Comdr Cotton, and Civil Engineer Prindle, I naturally hesitate to oppose the views of officers who have seen the relative merits of the broadside and turret systems tried in actual engagement. But I think the test presented by the operations before Charleston scarcely a fair one. It must be remembered that the monitors were then novel craft, their mechanism new to the service and their method of loading and firing developed only in the crudest manner. In the future turret ship we may hope to see, among other means of promoting rapidity of fire, hydraulic loading gear, and a hollow, central shaft for hoisting projectiles for breech loaders. No time will then be wasted in revolving the turret until the "shell whip shall be fair with the hatch." If, during a given time, we can throw the same amount of metal into a fort from a turret ship as we can from a broadside vessel, we will do the same amount of damage, and will ourselves receive less injury in return in our small target. I quite agree with Lieut. Stockton that an iron-clad armored on the Belt system is a most useful class of vessel, and the service would be fortunate indeed did it possess many of them. My object in the concluding remarks was simply to show the type; of ship most necessary for the navy at the present date to repel the attacks of foreign fleets.
Lieut. Rush. I should like to ask the lecturer if the Wilson plates he describes have ever been fitted to vessels. Mr. Miller also speaks of the use of air spaces. I would also enquire the extent of the experiments carried on in regard to distributing armor in two layers with an intervening water or air space.
Lieut. Miller. I see by the late papers that the Ajax and Agamemnon, two vessels of the Inflexible type, but of smaller dimensions, are to be fitted with compound armor; but, as no details of the plates have as yet reached this country, I cannot state whether the Wilson combination of steel and iron is to be used or not.
The only experiments to test the value of air spaces were made in England about three years ago. The thirty-eight ton gun fired an eight hundred pound shot completely through nineteen and one-half inches of iron, and ten inches of teak, at seventy yards range. The gun was next fired against a ten inch plate, and a four inch plate backed with thirteen inches of teak, a space of six feet being left between the two. When the second target was examined, after the experiment, it was found that the shot had passed through the ten inch plate, and had been broken to pieces, against the four inch plate without injuring the latter in the least degree. The apparent anomaly presented by the above experiment may be explained as follows; a shot strikes a thick plate and, like the tallow candle tired at a pine board, it finds its way through the iron; but during its passage it has developed in it so great an amount of heat that the metal of which it is composed is upset. The crystalline structure of the projectile is destroyed, but the surrounding plate, holding it in a vice, prevents the particles from separating. As soon, however, as the shot is released and passes into the air space, the least shock will shatter it.
I had not intended, Mr. Chairman, to present any novel method of construction, as air spaces and compound armor have not been sufficiently tested as yet to warrant their adoption; but the discussion having led towards the subject, it will not perhaps be out of place to show the manner in which the future turret ship may be armored.
The figure on the board is a rough sketch of a proposed sea going monitor. The outer plating ten inches thick, the inner four inches, with an interval of six feet between the two—Wilson armor to be used. The inner layer you will notice is carried, say four feet, below the water line before it slopes towards the keel. My idea in doing this is to deflect shot which may strike below the water line. The space between the two layers of armor is to be used as a coal-bunker, as experiments made during our war proved that coal was a great deflector, and tended to throw the projectile, upward or in the line in which it met the least resistance. It is scarcely possible that the coal would prevent a projectile, already upset while passing through the outer armor, from flying to pieces. The central spindle should be hollow and used for hoisting shot and shell. The base of the turret should be protected by the inclined armor.
Lieut. Brownson. Will Mr. Miller tell us why he makes his inner layer four inches thick, when, as he says, the projectile is already shattered after passing through the outer armor.
Passed-Asst Eng. Manning. I think Mr. Miller is slightly in error about the first iron-clad built in this country as it is my impression that the "Re d' Italia" built by Mr. Webb of New York about the year 1860 for the Italian government, was at least partially iron plated. She was sunk at the battle of Lissa in 1866 and is spoken of in the accounts of that fight as an iron-clad ram. Mr. Miller, in comparing the several systems, has omitted to mention the most vulnerable point of the monitor system—the deck—which has but little resistance to shot if struck at close quarters. Had the Merrimac been able to depress her guns sufficiently in her memorable fight with the Monitor I fear there would have been a different ending. At long range there is very little danger, as the angle at which a shot could strike the deck would be so acute as to cause it to glance.
Lieut. Miller. The relative thickness of the two layers must of course be determined by future experiments. I used four inches simply to illustrate the system, that being the thickness of the English target to which I referred.
I am indebted to Mr. Manning for drawing attention to the vulnerability of the deck of the monitors. It is undoubtedly their weak point, bat the use of inclined sides as shown in the drawing will obviate that defect, while the reduction of thickness of the new armor, will enable us to distribute it to better advantage. I have been unable to find any details regarding the Re d'Italia, but if I succeed in doing so will insert them as a note in the body of the lecture. Before the meeting adjourns I should like to express my thanks to Cadet Midshipmen Hunicke and Cramer for the excellent plates which accompany my lecture.
The Chairman. I have listened with extreme interest to the paper presented to us by Lieut. Miller, and I believe that I am expressing the feelings of all the members present in thanking Lieut. Miller for his very able paper.