United States Naval Artillery
From the time of the introduction of cast-iron cannons in 1558 until a comparatively late period, development in naval artillery proceeded at a very slow rate. The security that was attained by the adoption of cast-iron was so great, as compared with the danger attending the use of the more ancient artillery, that the new guns were regarded as fully supplying all the demands of a suitable battery. The guns were muzzle-loaders, making the manipulation simple, the previous rude attempts at breech-loading being abandoned. The number of calibres that were introduced was very numerous, partly to suit the weight of the batteries to the ships, and partly to accommodate the fancy of the time for placing in different parts of the ships guns varying much in size and destructive effect. The general character of the batteries and the multiplication of calibres can best be illustrated by noting the armament of two typical ships of the seventeenth century.
The Royal Prince, a British ship built in 1610, carried fifty-five guns. Of these, two were cannon-petronel, or 24-pounders; six were demi-cannon, medium 32-pounders; twelve were culverins, 18-pounders, which were nine feet long; eighteen were demi-culverins, nine-pounders; thirteen were rakers, 5-pounders, six feet long; and four were port-pieces, probably swivels. These guns were disposed as follows: on the lower gun-deck, two 24-pounders, six medium 32-pounders, and twelve 18-pounders; on the upper gun-deck the battery was entirely of 9-pounders; and the forecastle and quarter-deck were armed with 5-pounders, and the brood of smaller pieces which swelled the nominal armament.
The Sovereign of the Seas, built in 1637, in the reign of Charles I., was unequalled by any ship afloat in her time. She mounted on three gun-decks eighty-six guns. On the lower deck were thirty long 24-pounders and medium 32-pounders; on her middle deck, thirty 12-pounders and 9-pounders; on the upper gun-deck, “other lighter ordnance;” and on her quarter-deck and forecastle, “numbers of murdering pieces.”
In the obstinately contested actions between Blake and Van Tromp in the Cromwellian time, the ships and batteries did not differ in any great degree from those contemporaneous in construction with the Sovereign of the Seas; and when we remember the inferior character of the powder used in those days we can account for the duration of some of the engagements between the English and Dutch ships which were sometimes protracted through three days.
The brood of “murdering pieces” of small calibre and little energy was, after many years, dispersed by the introduction of carronades—a short cannon of large calibre, which was found to be a convenient substitute for the 8-pounders and 9-pounders on upper decks, and for the “lighter ordnance,” which was ineffective; but this change was brought about slowly, as is seen by referring to the batteries of some ships which fought at Trafalgar.
The Spanish seventy-fours in that action had fifty-eight long 24-pounders on the gun-decks; on the spar-deck, ten iron 36-pounder carronades and four long 8-pounders; and on the poop, six iron 24-pounder carronades—total, seventy-eight guns.
The Victory, the English flag-ship, mounted on her three gun-decks ninety long 32, 24, and 12 pounders, and on the quarter-deck and forecastle, ten long 12-pounders and two 68-pounder carronades.
The Santissima Trinidada mounted on the lower gun-deck thirty long 36-pounders; on the second deck, thirty-two long 18-pounders; on the third deck thirty-two long 12-pounders; and on the spar-deck, thirty-two 8-pounders. In the British accounts she is said to have had one hundred and forty guns, which number must have included swivels mounted for the occasion.
At the end of the eighteenth century the 18-pounder was the preferred gun for the main-deck batteries of frigates, guns of larger calibre being found only on the lower decks of line-of-battle ships. The 18-pounder was the maximum calibre that was employed on board the ships of the United Colonies of North America in the war of the Revolution. The resources of the colonies did not admit of building ships to contend with vessels fit to take their place in line of battle, but such as were constructed were well adapted to resist the small British cruisers, and to capture transports and store-ships. The so-called frigates of that day were vessels varying from six hundred to a thousand tons, and, according to their capacity, carried 12-pounders or 18-pounders in the main-deck batteries. There was usually no spar-deck, but the forecastle and quarter-deck, which were connected by gangways with gratings over the intermediate space, were provided with an armament of light 6, 9, or 12 pounders. A few carronades came into use during this war.
At the conclusion of this war the Colonial fleet disappeared, and it was not until the time of the depredations on the growing commerce of the United States by the Algerine corsairs that Congress felt justified in incurring the expense of establishing a national marine. The ships which were built under the law of 1794 were fully up to the most advanced ideas of the time, and some of these ships carried on their gun-decks a full battery of 24-pounders, thirty in number, while the others were armed with 18-pounders on the gun-deck, with spar-deck batteries of 9 and 12 pounders, the carronade not having been yet definitely adopted for spar-deck batteries.
It is not until the war of 1812 that we find the carronade fully established as the spar-deck armament of frigates. The Constitution and the Guerrière carried 32-pounder carronades of very similar weight and power in the place of the long guns of smaller calibre on the spar-deck. The original name of this piece of ordnance was the “Smasher,” the leading purpose of the inventor, General Melville, of the British artillery, being to fire 68-pounder shot with a low charge, thus effecting a greater destruction in a ship’s timbers by the increased splintering which this practice was known to produce. Carronades of small calibre were subsequently cast, which were adopted for spar-deck batteries of frigates and line-of-battle ships, and, as they grew in favor, formed the entire battery of sloops-of-war and smaller vessels until about 1840, when the attention that had been given for some years to the subject of naval ordnance began to assume tangible shape, and the effort was made to proceed in this matter in accordance with an intelligent system.
The advantage of large calibre was firmly impressed upon those who occupied themselves with the ordnance matters of the navy. As the fleet was developed, the 24-pounder gave way to the 32-pounder, and for the lower-deck battery of line-of-battle ships the 42-pounder was introduced. Some 42-pounder carronades were also introduced as spar-deck batteries for these larger ships. With the disappearance of this class of ship the 42-pounder was abandoned, and the 32-pounder was retained as the maximum calibre, different classes being assigned to different sizes of ships. These classes were divided into the gun proper, with 150 pounds of metal to one of shot; the double-fortified gun, with 200 pounds of metal to one of shot; and the medium gun, with 100 pounds of metal to one of shot. The carronade of the same calibre, mounted on a slide, had a proportional weight of 65 pounds of metal to one of shot.
In the interval between 1840 and 1845 the double-fortified 32-pounder was replaced by a gun of the same calibre of 57 hundred-weight, called the long 32-pounder; and to suit the capacity of the different classes of ships then in the service, there were introduced the 32-pounders of 46 hundred-weight, 42 hundred-weight, and 27 hundred-weight, in addition to the regular medium gun of 32 hundred-weight. This period also marks the introduction of shell-guns as part of the battery.
To this time no explosive projectiles had been used with cannons properly so called; their use had been limited to mortars and howitzers. The mortar was originally used for projecting huge balls of stone at high angles. The first practical use made of them for projecting bombs was in 1624, but the unwieldy weight of the mortar and its bomb, the latter sometimes exceeding 300 pounds, prevented their use in field operations. To provide for this, light mortars were cast, which, being mounted on wheels, were denominated howitzers. Frederick the Great of Prussia brought this form of artillery to its highest development for field and siege use, and the Continental powers of Europe adopted it to a large extent for projecting bombs at high angles of fire. The mortar has never had a place in regular naval armaments; it has been used afloat for bombardment of cities and fortified positions, but never with a view to contending with ships.
The success attending the use of explosive projectiles at high elevations did not lead at once to their application to horizontal firing from cannons. An important link in the progress of the idea resulted from the effort to avail of the advantage of ricochet firing with bombs. In order to effect this, the angle of elevation had to be reduced to enable the bomb to roll along the ground. The reduced angle of elevation was still greater than that used for cannon, but the success of the experiment led to the casting by the French of an 8-inch siege howitzer, which, in connection with the development in the manufacture of fuses, made it practicable to apply the idea of firing shells, like shot, horizontally, and the chief object in view seems to have been to operate against ships.
The combining of the elements necessary for the achievement of this important step in naval artillery is by common consent credited to General Paixhan, of the French artillery, who, though not claiming the invention of any of the numerous details involved in the system, succeeded in so judiciously arranging the parts as to make the system practicable by which the whole character of naval armaments was revolutionized.
Following the progressive ideas of the age, shell-guns were introduced in the United States navy. These were of 8-inch calibre, and of weights of 63 hundred-weight and 55 hundred-weight. The guns were shaped in accordance with the form adopted by General Paixhan, and were easily distinguishable in the battery from the ordinary shot-gun. From this circumstance they obtained the title of Paixhan-guns, though there was nothing special in the gun itself to merit an appellation. The whole system was Paixhan’s; the gun was only a part of the system.
It required many years to bring the shell-gun into such general application as to displace the solid-shot gun. They were assigned tentatively to ships in commission, and in 1853, by a navy regulation, the battery of a frigate was provided with only ten of these guns, which were collected in one division on the gun-deck. The first vessel in the United States navy whose battery was composed exclusively of shell-guns was the sloop-of-war Portsmouth, in 1856. This vessel carried a battery of sixteen 8-inch shell-guns of 63 hundred-weight. These were among the first of a new pattern of gun for which the navy is indebted to the skill and study of the late Rear-admiral Dahlgren.
The determination of the best form for cannons was a question which had occupied the minds of artillerists for some years. In the older guns the thickness of metal was badly distributed; it was too uniformly extended along the entire length, not arranged in such proportions as to accord with the differing strains along the bore. Colonel Bumford, of the United States Ordnance, had been among the first to consider this subject, and for many years the results of his experiments had guided construction to a great degree. General Paixhan made a further step in advance by reducing very much the thickness of metal along the chase of his guns, but it remained for Rear-admiral Dahlgren to produce the perfection of form in the gun so widely known bearing his name. In this gun the thickness of metal is proportioned to the effort of the gases in the bore, and all projections and angular changes of form are suppressed, giving to all parts a curved and rounded surface. The suppression of angular formations on the exterior of a casting has a remarkable effect on the arrangement of the crystals while cooling. These arrange themselves normal to the cooling waves, which, if entering from directions not radial with the cylindrical casting, produce confusion in their arrangement, establishing planes of weakness where the waves meet, which, in case of overstrain on the piece, assist rupture and determine the course of the fracture.
With the introduction of the Dahlgren shell-gun the transition of the artillery of the United States navy may be said to have been completed. The shell-gun of 9-inch and 11-inch calibres followed the 8-inch, and ships were armed with such as were appropriate to their capacity as rapidly as the new guns could be manufactured. When fully equipped, the armament of the United States navy was superior to that of any other navy in the world.
The substitution of shells for solid shot marks an important epoch in naval artillery. The probable effect of a shot could be predetermined and provided for; that of a shell was unknown. In order to produce serious injury with a shot, it was necessary to perforate the side of an enemy. This was not indispensable with a shell; with the latter, perforation might be dispensed with, as penetration to such a depth as would give efficacy to the explosion might prove more destructive to the hull than would absolute perforation. With the shot, damage was done to life and material in detail; with the shell, if successfully applied, destruction was threatened to the entire fabric, with all it contained. Naval artillery entered a new phase; the rough appliances of the past would no longer answer all demands. The founder could not alone equip the battery; the laboratory was called into use, and pressed to provide from its devices. The “new arm” depended upon the successful working of the fuse of the shell, without which it was but a hollow substitute for a solid shot, and this detail demanded the utmost care in preparation. It was the perfecting of this device which, more than aught else, delayed the general adoption of the new artillery for so long a time after its advantages had been recognized.
The fuses that were used to explode the ancient bombs were long wooden plugs, bored cylindrically, and filled with powder condensed by tamping it to a hard consistency. The fuse case projected from the bomb, and to avoid being bent by the shock of discharge, was placed carefully in the axis of fire. Before the discharge of the mortar the fuse was lighted by a match. In applying the fuse to shell-guns fired horizontally, the problem was so to arrange it as to ignite it by the flame of discharge, and so to support it in the wall of the shell as to prevent any dislocation of the fuse composition, the cracking of which would permit the penetration of the flame into the mass. This was successfully accomplished, and the United States navy fuse was justly famous, one feature of it being a simple but most effective device called a “water-cap,” which guarded against the injurious introduction of sand or water when the shell was fired en ricochet. The introduction of a safety-plug in the bottom of the fuse case, which required the shock of discharge to displace it in order to open a way of communication between the fuse and the bursting charge in the shell, and the absence of all accidents in manipulation, inspired such confidence that the new arm advanced to favor, and both officers and men were proud to be identified with it.
Previous to the introduction of shells there had been in use incendiary projectiles, not explosive, but intended to set fire to an enemy’s vessel. Hot shot were applied to this purpose, but the use of these was chiefly confined to shore batteries, where a suitable heating furnace could be conveniently provided. The projectile for this purpose chiefly used from ships was the carcass, which was a shot in which several radial cylindrical holes were formed which were filled with powder tamped to a hard consistency; these columns of composition were ignited by the flame of discharge, and continued to burn until consumed. The flame issuing from these holes served to ignite consumable material in their vicinity. The chief danger from a carcass was from lodgment in the side of a ship; if it landed on deck it could be removed and thrown overboard, as there was no danger from explosion; the addition of the bursting charge in the cavity of a shell produced a projectile which was far in advance both for generating a flame and for preventing interference with its mission.
The probable destructive effect of shells exploding in the sides or on the open decks of ships was thoroughly recognized, and experiments at targets sufficiently proved it; but circumstances on a proving-ground and in action are so dissimilar that the experience of a naval engagement was looked forward to with much interest, in order to satisfy as to the effect of the new projectile in all the varying conditions of a sea-fight. Referring to the history of the past thirty years, which marks the period of the general introduction of shell-guns, it is remarkable how few engagements between ships have taken place; but on every occasion of the use of shells, when unarmored vessels were engaged, the effect has been most decided and complete. Three instances only can be referred to of purely sea-fights, viz., the engagement between the Russian and Turkish fleets at Sinope in 1853, during the Crimean war, the engagement between the United States steamer Hatteras and the Confederate cruiser Alabama during the war of the rebellion, and the fight between the Kearsarge and the Alabama during the same war. In the affair at Sinope the Russian ships used shells; the Turkish had only solid shot. The result was the total destruction of the Turkish force. Not one ship escaped; all were burned or sunk. The fight between the Alabama and the Hatteras resulted in the sinking of the Hatteras; and the contest between the Alabama and the Kearsarge ended the career of the Alabama. And it may be noticed that but for the failure to explode of a shell that was embedded in the stern-post of the Kearsarge, that vessel might have accompanied her antagonist to the bottom of the sea.
The gallant attempt of Rear-admiral Lyons with the British wooden fleet before the forts of Sebastopol is an instance which proved the uselessness of subjecting unarmored vessels to the steady fire of fortified positions using shells from their batteries.
One other instance of a sea-fight can be cited in the engagement in 1879 between two Chilian armored vessels and the lightly armored Peruvian turreted vessel Huascar. The Huascar was terribly over-matched during this fight, but at its conclusion her boilers and engines were intact, and indentations on her sides showed that her light armor had deflected a number of projectiles; but the effect of the shells that had burst on board of her was apparent in the great destruction of life.
The very decisive engagement which took place at Lissa in 1866, between the Austrian and Italian fleets, should not be omitted in alluding to sea-fights of a late period; but this action can hardly be quoted as one in which the element of shell-fire can be recognized as the exclusive cause of destruction, for the remarkable impetuosity and dash of the attack and the desperate use of the ram produced a crisis which obviated the necessity for continuous bombardment with cannon.
The necessity of providing a defence against shells was recognized both by England and France during the Crimean war, and a protection of armor was supplied to some floating batteries built at that time which were intended to operate before fortified positions; and at the conclusion of the war the English built the Warrior and the French built La Gloire. These were the first specimens of iron-clad ships of war. They were capable of resisting successfully the entrance of shells from guns of the period. It is thus seen that almost coincident with the general adoption of horizontal shell-firing, naval construction entered a new phase, and a new problem was submitted to the naval artillerist.
Against an iron-faced target the solid shot might be partially effective, but the impact of the spherical shell was harmless, and the explosive effect of the bursting charge enclosed in it would be superficial. This was amply demonstrated in actual practice during our war experience, notably at Mobile Bar, in the engagement with the Confederate iron-clad Tennessee, the roughly constructed armor of which vessel resisted a storm of our heaviest shells.
The impotency of the spherical shell against armor being recognized by foreign governments, they proceeded to develop the rifled cannon, which with its elongated projectile offered the means of effecting the object of the time—to perforate armor with an explosive projectile. Our authorities, however, persevered in their faith in the smooth-bore, and held that the racking effect of a spherical projectile of sufficiently large calibre was superior to that produced by the perforation of a rifle projectile of inferior diameter. The 15-inch and 20-inch smooth-bore cannons were cast in accordance with this idea, and the racking side of the question was so obstinately held that the British government imported in 1867 from the United States a 15-inch gun for the purpose of determining by their own experiments what foundation there was for the advantages that were claimed for it. The gun was bought of Charles Alger & Co., of Boston; it weighed nineteen tons, and threw a cast-iron spherical solid shot of about four hundred and fifty pounds. It was mounted at Shoeburyness, and was fired in competition with English rifled cannons of 9-inch and 10-inch calibres. The result of the experiments went to show that against a target with a power of resistance inferior to the energy of the projectile the effect of the large sphere at short range is more disastrous than that of the elongated rifle projectile of the same weight; but that against a target able to resist the total energy of both the injury done by the rifle projectile is by far the greater. The comparative effect is well shown on a target called the “Millwall Shield,” consisting of a plate nine inches in thickness, backed by Hughes’s hollow stringers—an arrangement of target which to the time of the experiment had proved invincible. The 15-inch smooth-bore spherical shot rebounded from the target six feet, leaving a 3-inch indentation on the plate, while the 9-inch rifle projectile, weighing two hundred and fifty pounds, made complete penetration of the plate, passing two or three inches into the backing, and the 10-inch rifle projectile, weighing four hundred pounds, penetrated to the rear of the backing itself.
It should be mentioned in this connection that the United States government adopted during the war of the rebellion a rifled cannon proposed by Captain Parrott of the West Point Foundery, New York, of which many were introduced into both the navy and army, and did good service as long as the charges of powder were limited in weight; but when these guns were called upon for work requiring great endurance, they proved untrustworthy and dangerous to those who served them. At the naval bombardment of Fort Fisher several of them burst, causing loss of life on board the vessels of which they formed the armament. They were constructed of cast-iron, having a coiled hoop of wrought-iron shrunk around the breech. They have ceased to form a part of our naval armament.
During the years of inaction in the United States that have intervened since these experiments, the smooth-bore partisans have had time to reflect and to learn lessons of practical usefulness from observing what has been transpiring abroad. Opportunities have been afforded to note the progress made in armor and artillery, and though the smooth-bore shell is still operative against unarmored vessels, the advantages of the rifled gun under all the circumstances of navy experiences have been admitted, and in the transition through which our naval artillery is now passing we are not embarrassed by the presentation of views antagonistic to the principles on which it has been determined our new artillery is to be constructed. The system at the basis of our present acts is founded on a comprehensive view of the whole subject, and is intended to provide our ships with a surplus of offensive power over what their capacity for defence might seem to call for.
Our navy will possess a certain number of armored vessels for coast defence, and armored sea-cruisers are certain to be included in the list, but the more numerous class will be unarmored, and the first problem to be solved is that of providing for these a suitable armament.
The work to be done by an unarmored cruiser must be done from a distance when risking an engagement with an armored enemy. The superiority of armament must compensate for deficiency in defensive power which precludes close quarters. To make these ships effective they must be armed with guns capable of doing an extraordinary amount of work, and yet the size of the vessels will not admit of their carrying guns of immense weight. In order to get this amount of work out of a comparatively light gun, we must secure great initial velocity for the projectile. This can only be done by burning a large charge of powder, which involves a long bore in which to burn it, while care is necessary to secure a large margin of strength in the material of which the gun is constructed. These essential demands required a radical change in the form and material of our present armament; they also forced a change in the method of construction.
The superior fitness for cannons of steel over cast-iron was recognized many years ago, but the difficulty of casting steel in large masses prevented the introduction of steel guns, and the generally acceptable treatment of cast-iron made it answer satisfactorily the demands for gun-metal not subjected to unusual strains. Mr. Frederick Krupp, of Essen, in Germany, was the first steel manufacturer who succeeded in casting steel in large masses, and he produced a number of steel guns cast from crucibles in solid ingots, which were bored, turned, and fashioned as in the case of cast-iron smooth-bore guns. These guns held a position in advance of other manufactures on the score of strength of material. But the introduction of the rifle system, the call for higher velocities, the increased charges of powder, with the consequent increase of strain, enhanced by the friction attending the passage of the projectile forced along the bore, had the effect of calling attention to the weakness that was inherent in the method of construction of cannons. It is well known that an explosive force operating in the interior of a hollow cylinder of any thickness is not felt equally throughout the wall of metal; the parts near the seat of explosion are called upon to do much more work in restraining the force generated than are the parts more remote. It has been determined that the strain brought upon the portions of the wall is in inverse proportion to the squares of their distances from the seat of effort. Thus, in a gun cast solid, if we take a point two inches from the bore, and another four inches from the bore, the strain felt at those points respectively will be inversely in the proportion of four to sixteen, or, in other words, the metal at two inches from the bore will be strained four times as much as that at the distance of four inches. From this it can be seen that the metal near the seat of effort may be strained beyond its tensile strength, while that more distant is only in partial sympathy with it. Rupture thus originates at the interior portion, and the rest of the wall yields in detail. No additional strength of material can change this relationship between the parts; they result from a law, and show that this method of construction for a cannon is untrustworthy where the strains approach the tensile strength of the material.
The means of providing against this successive rupture of over-strained parts is found in the “built-up gun,” in which an interior tube is surrounded by encircling hoops of metal, which are shrunk on at sufficient tension to compress the portions which they enclose. This is the principle of “initial tension,” which is the basis of the modern construction of cannons. By adopting this method, an ingot to form a tube to burn the required amount of powder can be cast of a light weight in comparison with what would be needed for a complete gun, and the strength and number of reinforcing rings to be shrunk around it can be readily determined, proportioned to the known strain that will be brought upon the bore of the piece. The late developments in the manufacture of steel by the open-hearth process remove all difficulty to procuring the necessary metal in masses suitable for all parts of the heaviest guns.
The built-up steel gun is the one now adopted in Europe by the leading powers, and it is the gun with which the United States navy will be armed; but, before its final adoption, efforts were made to convert old smooth-bore cast-iron guns into rifles, and to construct new guns partially of steel and partly of wrought-iron. As some of these methods of conversion offered an economical means of acquiring rifled cannons, our naval authorities were led into the error of countenancing the effort to a moderate degree.
The system that was adopted was that originally suggested by Mr. P. M. Parsons in England, which was afterwards patented by Major Palliser, R.A., and bears his name. It consisted in enlarging the bore of a cast-iron gun, and inserting a tube of wrought-iron formed of a bar arranged in the form of a coil when heated. The tube was expanded by firing charges of powder, and afterwards rifled. The guns are muzzle-loaders, and are not increased in length beyond that of the cast-iron gun which forms the casing for the tube. The length is thus limited in order to preserve the preponderance of the piece, and because of the want of longitudinal strength in the coil, which cannot be depended on beyond a few tons’ strain; the arrangement of metal in a coil provides very well for circumferential or tangential strains, but in the Palliser conversion the longitudinal strength depends on the cast-iron casing. The idea of the coiled wrought-iron tube originated with Professor Treadwell, of Harvard University, in 1841. He utilized it by enclosing a tube of cast-iron or steel in the same manner as it is applied in the wrought-iron Armstrong and Woolwich guns.
The administration of our naval ordnance has abandoned conversions, and has concentrated its efforts on the production of an armament of built-up steel guns. The system of construction that has been adopted originated in England, but was for many years ignored by the government authorities. It involved the use of steel in all its parts, and this was charged as an objection, as confidence in this metal was not established in the minds of the English artillerists. That government committed itself entirely to the wrought-iron gun proposed by Mr. (now Lord) Armstrong, whose system was a reproduction of that successfully experimented on by Professor Treadwell, and the entire force of the government works at Woolwich and of the Armstrong works at Elswick-on-the-Tyne was occupied with the production of this style of ordnance. The English steel gun invented by Captain Blakely and Mr. J. Vavasseur was ignored in England, but its merit could not be suppressed, and its superiority has forced a tardy recognition by that government.
This gun came prominently into notice for a short time at the breaking out of the war of the rebellion: some guns were imported for the service of the Southern States. At the exhibition in London in 1862 a Blakely 8.5-inch gun was one of the features of attraction in the department of ordnance. The principle of the construction was shown in this gun, consisting in shrinking a long jacket of steel around an enclosed steel tube, the jacket extending to the trunnions. Mr. Vavasseur was the manager of the London Ordnance Works, and was associated with Captain Blakely in the manufacture of his earlier guns, but the entire business soon fell into the hands of Mr. Vavasseur, whose name alone is associated with the succeeding developments of the gun.
In 1862 the guns manufactured by Mr. Krupp were solid forgings. He advanced but slowly towards the construction of built-up cannons, and it was not until the failure of some of his solid-cast guns that he entered on the built-up system. His first steps were to strengthen the rear portion of new guns by shrinking on hoops, and to increase the strength of old guns he turned down the breech and shrunk on hoops. He confined this system of strengthening to the rear of the trunnions until he was reminded of the necessity of strength along the chase of the gun by the blowing off of the chase of some 11-inch guns of his manufacture. His system was then modified so as to involve reinforcing the tube of the larger calibred guns along its whole length with hoops, and his later and largest productions are provided with a long jacket reinforcing the entire breech portion of the tube—a virtual adoption of the great element of strength which has always formed the essential feature in the Vavasseur gun which is now adopted in the United States navy.
In the building up of the steel gun for the navy advantage is so taken of the elastic characteristic of the metal that all parts tend to mutual support. The gun proper consists of a steel tube and a steel jacket shrunk around it, reaching from the breech to and beyond the location of the trunnion-band. Outside the jacket and along the chase of the gun there are shrunk on such hoops as the known strain on the tube may make necessary for its support. The tube is formed from a casting which is forged, rough-bored, and turned, and then tempered in oil, by which its elasticity and tensile strength are much increased. It is then turned on the exterior, and adjusted to the jacket, the proper difference being allowed for shrinkage. The jacket, previously turned and tempered, is then heated, and rapidly lowered to its place. The front hoops over the chase are then put on, and the gun is put into a lathe and turned to receive the trunnion-band and rear and front hoops. The gun is then fine-bored and rifled.
Each part, as successively placed in position, is expected to compress the parts enclosed through the initial tension due to contraction in cooling. This tension is the greater the farther the part is removed from the tube; thus the jacket is shrunk on at a less tension than are the encircling hoops. By this means full use is made of the elastic capacity of the tube which contributes the first resistance to the expanding influence of the charge. The tension of the jacket prevents the tube being forced up to its elastic limit, and it in turn experiences the effect of the tension of the other encircling parts which contribute to the general support; thus no part is strained beyond its elastic limit, and on the cessation of the pressure all resume their normal form and dimensions. A comparison of this method of common and mutual support of parts with that given by the wall of a gun cast solid will serve to demonstrate the superior strength of the construction. In order to achieve this intimate working of all the parts it is necessary that the metal of which they are respectively composed must be possessed of the same essential characteristics; in a word, the gun must be homogeneous. It was the absence of this feature in the Armstrong gun which has caused its abolition. This gun was built up, and the parts were expected to contribute mutual support, but the want of homogeneity between the steel tube and the encircling hoops of wrought-iron made it impossible for them to work in accord, in consequence of the different elastic properties of the two metals, which, after frequent discharges, resulted in a separation of surfaces between the tube and hoops, when the tube cracked from want of support.
In the construction of the guns for the United States navy, as in the new steel guns now being manufactured in England, the theory of the built-up system is practically conformed to; more so than by Krupp or the French artillerists, who use a thicker tube than is considered judicious at Woolwich or at the Washington navy-yard. Any increase of thickness of the tube beyond what is necessary to receive the initial pressure of the charge is open to the objections made to the gun with a solid wall, the proportion of the strain communicated to the hoops is reduced, and rupture may ensue from overstraining the tube. The thicker the tube, the less appreciable must be the compression induced by the tension of the encircling hoops.
The gun is a breech-loader. The system adopted for closing the breech is an American invention (see note, p. 257), but having been employed in France from the earliest experimental period, it is known as the French fermeture. A screw is cut in the rear end of the jacket to the rear of the tube, and a corresponding screw is cut upon a breech-plug. The screw threads are stripped at three equidistant places, the screw and plane surfaces alternating, thus forming what is called an “interrupted” or “slotted” screw. The screw portions of the breech-plug enter freely along the plane longitudinal surfaces cut in the tube, and being then turned one-sixth of its circumference, the screw of the plug locks in that of the tube, and the breech is closed.
The success of this system of breech mechanism was not so pronounced on its introduction as it is to-day. The plug forms the base of the breech of the gun, and all the effort of the gases to blow out the breech is exerted at this point. The impact upon the end of the plug is very severe, and has a tendency to upset the metal, thereby increasing the diameter of the plug, which would prevent its removal after the discharge of the piece. With quick-burning powder, as was generally in use for cannons at the inception of the breech-loading experiments, this result ensued if the charges of powder were carried above a certain limit, and the consequent restriction that was put upon velocities was a serious obstacle to the adoption of the system; but the progress that has been made of late years in the science of gunpowder manufacture has relieved the subject from this embarrassment, powder being now provided which communicates very high velocities while developing pressures so moderate and regular as to be entirely under the control of the artillerist.
The original guns, four in number, constructed with breech mechanism on the French fermeture principle for the British government during the Crimean war are now in the “Graveyard” at Woolwich Arsenal.
The projectiles for the new armament are of two kinds; both, however, are shells. That for ordinary use against unarmored vessels is styled the common shell, and is of cast-iron. The length bears a uniform proportion to the gun, being in all cases three and a half calibres. The armor-piercing shell is made of forged steel, and is three calibres in length. The following table gives the particulars, approximately, of the common shell:
| Gun. | Length. | Weight. | Bursting Charge. | |
|---|---|---|---|---|
| Inches. | Calibre. | Pounds. | Pounds. | |
| 5 inch breech-loading rifle | 17.97 | 3.59 | 60 | 2 |
| 6-inch breech-loading rifle | 20.90 | 3.48 | 100 | 4 |
| 8-inch breech-loading rifle | 28.10 | 3.51 | 250 | 12 |
| 10 inch breech-loading rifle | 35.00 | 3.50 | 500 | 22 |
| 12 inch breech-loading rifle | 42.00 | 3.50 | 850 | 38 |
| 16-inch breech-loading rifle | 56.00 | 3.50 | 2000 | 90 |
The armor-piercing shell of the same weight is reduced in length, and its walls are thicker; the bursting charge is consequently much reduced. The following are the particulars, approximately determined:
| Gun. | Length. | Weight. | Bursting Charge. | |
|---|---|---|---|---|
| Inches. | Calibre. | Pounds. | Pounds. | |
| 5-inch breech-loading rifle | 15.07 | 3.01 | 60 | 1 |
| 6-inch breech-loading rifle | 17.91 | 2.98 | 100 | 1.50 |
| 8-inch breech-loading rifle | 24.25 | 3.03 | 250 | 3.50 |
| 10-inch breech-loading rifle | 30.00 | 3.00 | 500 | 7 |
| 12-inch breech-loading rifle | 36.00 | 3.00 | 850 | 14 |
| 16-inch breech-loading rifle | 48.00 | 3.00 | 2000 | 30 |
The rifle motion is communicated by one rotating ring of copper, which is placed at the distance of 1.5 inch from the base of the projectile.
The uniform windage for all calibres is.04 inch; thus, taking the 6-inch gun as an example, the diameter of the bore across the lands is 6 inches, the diameter of the shell is 5.96 inches, the depth of the grooves is.05 inch; thus the diameter of the bore across the grooves is 6.10 inches. In order to permit the rotating ring to fill the grooves, it must have a diameter of 6.14 inches; this causes a squeeze of.05 inch between the lands and the rotating ring.
There is no subject in the development of the new naval artillery more important than the powder. That used with the old artillery is entirely unsuited to the new conditions that obtain in the modern high-power guns. A brown powder, introduced first in Germany, has exhibited decided advantages over all others, and the efforts to reproduce it have been thoroughly successful at the Du Pont Mills. It is generally known as “cocoa” powder. Its peculiarity exists in the method of preparing the charcoal; this affects the color, and results in a brown instead of a black powder. With this powder, experiments with the 6-inch gun give a muzzle velocity of over 2000 feet per second with a projectile of 100 pounds, using charges of 50 pounds, and this result is obtained with less than 15 tons pressure per square inch in the powder chamber. The grain is prismatic, with a central perforation, and as regards its rate of burning, is under complete control in the manufacture; the form provides an increasing surface for the flame during the period of combustion, thus relieving the gun from abnormal pressures at the moment of ignition, but continuing the extreme pressure farther along the bore. The progressive nature of the combustion is very apparent when comparing an unburned grain with others partially consumed, blown out from the gun.
The gun-carriage, which is a separate study in itself, is carried to a high pitch of perfection, and presents many features being adopted abroad. The importance of a suitable carriage can be appreciated by inspecting the following table, which exhibits the energy that must be controlled by it:
| Gun. | Weight of Charge. | Weight of Projectile. | Muzzle Velocity. | Muzzle Energy. | Penetration in Wrought-iron. | Muzzle Energy per Ton of Gun. | Weight of Gun. | Weight of Carriage. |
|---|---|---|---|---|---|---|---|---|
| Pounds. | Pounds. | Feet. | Ft.-Tons. | Inches. | Ft.-Tons. | Pounds. | Pounds. | |
| 5-inch steel breech-loading rifle | 30 | 60 | 1915 | 1,525 | 10.7 | 552 | 6,187 | 4,200 |
| 6-inch steel breech-loading rifle | 50 | 100 | 1915 | 2,542 | 13.2 | 521 | 11,000 | 6,400 |
| 8-inch steel breech-loading-rifle | 125 | 250 | 2050 | 7,285 | 18.2 | 560 | 28,000 | 14,000 |
| 10-inch steel breech-loading rifle | 250 | 500 | 2100 | 15,285 | 23.7 | 588 | 58,240 | 32,482 |
| 12-inch steel breech-loading rifle | 425 | 850 | 2100 | 25,985 | 27.6 | 591 | 44 tons | .... |
| 14-inch steel breech-loading rifle | 675 | 1350 | 2100 | 41,270 | 32.2 | 550 | 75 tons | .... |
| 16-inch steel breech-loading rifle | 1000 | 2000 | 2100 | 61,114 | 36.8 | 571 | 107 tons | .... |
This energy, total energy, expresses the work that the gun can perform. It is expressed in foot-tons, and signifies that the energy developed is sufficient to raise the weight in tons to a height of one foot. Thus the projectile from the small 5-inch gun, weighing sixty pounds, fired with a charge of thirty pounds of powder, leaves the gun with an energy capable of lifting 1525 tons to the height of one foot! Comparing this with the energy developed by the 100-ton hammer at the forge of Le Creuzot in France, the energy of which is 1640 foot-tons, we have a most striking illustration of the power of gunpowder, and the testimony in the table as to the energy developed per ton of gun more forcibly exhibits the perfection of a manufacture which, with so little weight of gun, can develop such gigantic power.
It is this power, united with a moderate weight of gun, which will enable our unarmored cruisers to hold their own with vessels moderately armored. The power of the battery is greater than is required to contend with unarmored ships, there is a great surplus of power of offence, and the effort is very properly made to sustain this at the highest practicable point. The table shows that the 5-inch gun can perforate 10.7 inches of wrought-iron at the muzzle; but the results given in tables are based on deliberate firing made on a practice-ground, with the position of the target normal to the line of fire. Such conditions cannot obtain during an action at sea, for, besides the modified effect caused by increased distance of target, it must be borne in mind that the side of an enemy’s ship will be presented at varying angles, which introduces the element of deflection, than which no cause is more detrimental to penetration. Though the table states a fact, the practical effect of the projectile will be far less than is stated, hence the wisdom of providing a large surplus of power to compensate for the resistance to its operation.
It will readily be conceded that the artillerist has a very responsible duty to perform in so designing his gun that the parts shall lock and interlock to guard against chance of dislocation in the structure. A study of the illustration of the 6-inch built-up gun as constructed at the Washington navy-yard will show the system there adopted.
In the list of guns each calibre is represented by one gun. We have not, as of old, several guns of the same calibre differing in weight; multiplicity of classes will be avoided; but this will apply only to the main battery, for history is singularly repeating itself at this time in the restoration of the “murdering pieces” which have been cited as forming part of naval armaments in the seventeenth century. The needfulness of machine guns for operating against men on open decks, for effecting entrance through port-holes, for repelling attacks in boats, and for resisting the approach of torpedo-boats, is so widely recognized that no vessel of war is considered properly equipped without a secondary battery of these “murdering pieces.” They are mounted on the rail, on platforms projecting from the sides and in the tops. The types adopted in the United States navy are the Hotchkiss revolving cannon and rapid-firing single-shot guns, and the smaller calibre machine guns of Gatling. The heavier pieces, throwing shells of six pounds weight, are very effective against vessels of ordinary scantling.
In contemplating the present condition of our new naval armament we have the consolation of knowing that, so far as concerns the study of the subject generally and in detail, the designs, and the initial manufacture, all has been done that could have been done with the resources available. What has been achieved has been without the facilities that are provided in modern gun-factories; but notwithstanding all the drawbacks, it is probably safe to assert that no guns in the world to-day are superior to those that have been fabricated at the Washington navy-yard of steel on the new adopted pattern. The work at this ordnance yard is carried on without ostentation; there is no flourish of trumpets accompanying its operations; it is not advertised, and the people do not yet know how much they owe to the ordnance officers of the navy for the initiation of this new industry, which enables us to assert our ability to advance in this manufacture through the incontrovertible proof of work accomplished. The results are meagre in quantity, and at the present rate of manufacture it will require many years to equip our fleet with modern artillery; this should be remedied, as there is now no doubt as to the success of the productions of this establishment. The plant should be enlarged on a liberal and well-matured plan, and the work should be encouraged by generous appropriations.
It may not be generally known that the steel forgings required for the few 8-inch and the two 10-inch guns now in hand were imported from abroad, for the reason that they could not be furnished of domestic manufacture, from the want of casting and forging facilities in the United States for work of such magnitude. This was a deficiency in our resources that required prompt attention to secure us a position of independence in this important matter. The method of achieving the object was carefully studied out by a mixed board of army and navy officers, and presented in a document known as the “Gun Foundery Board Report,” and the subject received the attention of committees from both Houses of Congress. All of these reports virtually agreed as to the method, but there was a useless delay in action; large expenditures of money were required, and there was hesitancy in assuming the responsibility of recommending it. The object was of national importance, however, and public opinion demanded its accomplishment. The officers of the navy have proved their ability to carry on the work successfully; and if the opportunity be given they will establish the artillery of the United States navy in a position of which the country may again be proud.
Notes
Guns
The United States no longer depend upon foreigners for guns or armor, inasmuch as the circular issued in August, 1886, by the Navy Department inviting all domestic steel manufacturers to state the terms upon which they were willing to produce the steel plates and forgings required for ships and ordnance, has met with a prompt response. About 4500 tons were needed for armor, in plates varying from 20 feet by 8 feet by 12 inches thick, to 11.6 feet by 4.3 feet by 6 inches thick; and of the 1310 tons of steel forgings, 328 tons were intended for the 6-inch guns, 70 tons for the 8-inch, and 912 tons for the calibres between 10 and 12 inches, both inclusive. The rough-bored and turned forgings required by the contract were to weigh 3¼ tons for the 6-inch calibres, 5 tons for the 8-inch, 9½ tons for the 10-inch, 9¾ tons for the 10½-inch, and 12½ tons for the 12-inch. From the time of closing the contract twenty-eight 6-inch forgings were to be delivered in one year, and the remainder within eighteen months. All the 8-inch were to be ready within two years, and the 10-inch and larger calibres within two years and a half. The proposals opened on the 22d of last March showed that for the gun-forgings the Cambria Iron Company had bid $851,513, the Midvale Steel Company $1,397,240, and the Bethlehem Iron Company $902,230; and that for the armor-plates the Bethlehem Company had bid $3,610,707, and the Cleveland Rolling-mill Company $4,021,561. Subsequently the Navy Department awarded the contract to the Bethlehem Company, which agreed to furnish all the required steel at a total cost of $4,512,938.29.
The tests are so rigorous that a high quality of steel is sure to be produced. The specifications require the forgings to be of open-hearth steel of domestic manufacture, from the best quality of raw material, uniform in quality throughout the mass of each forging and throughout the whole order for forgings of the same calibre, and free from slag, seams, cracks, cavities, flaws, blow-holes, unsoundness, foreign substances, and all other defects affecting their resistance and value. While it is prescribed that the ingots shall be cast solid, latitude is given to the method of production; but no matter what method may be employed, the part to be delivered for test and acceptance must be equal in quality and in all other respects to a gun ingot cast solid in the usual way, from which at least 30 per cent. of the weight of the ingot has been discarded from the upper end and 5 per cent. from the lower end.
For breech-pieces each ingot must be reduced in diameter by forging at least 40 per cent.; in case tubes are forged upon a mandrel from bored ingots, the walls must be reduced in thickness by forging at least 50 per cent. Forgings are to be annealed, oil tempered under such conditions as will assure their resistance and again annealed, and no piece will be accepted unless the last process has been an annealing one. The forging must be left with a uniformly fine grain.
All these excellent results are the direct outcomes of the report made in 1884 by the Ordnance Board. 1st. That the army and navy should each have its own gun-factory; 2d. That the parts should be shipped by the steel-makers ready for finishing and assembling in guns; 3d. That the government should not undertake the production of steel of its own accord; 4th. That the Watervliet Arsenal, West Troy, N. Y., should be the site of the army gun-factory; and 5th. That the Washington navy-yard should be the site of the navy gun-factory. No action was taken upon the recommendation to establish gun-factories; but at the first session of the Forty-ninth Congress an appropriation of $1,000,000 was made for the armament of the navy, of which sum so much as the Secretary determined might be employed for the creation of a plant. Under this permission the gun-factory at the Washington navy-yard is now being established.
The construction of the breech-loading steel guns for the new cruisers has been energetically pushed. Slight modifications in the original designs were made necessary by the adoption of slower burning powder, which carried the pressure still farther forward in the bore, and, in the case of some foreign guns, caused their destruction. Though our guns have not suffered from any such accident, it has been deemed a wise precaution to give the 8-inch guns of the Atlanta two additional chase hoops, and to hoop all other pieces of this calibre to the muzzle.
From a memorandum kindly furnished by Lieutenant Bradbury, United States navy, it is learned that the number and calibre of the new guns now finished, under construction, or projected, are as follows:
| Name of Ship. | Calibre. | ||||
|---|---|---|---|---|---|
| 5-inch. | 6-inch. | 8-inch. | 10-inch. | 12-inch. | |
| Dolphin | None. | 1 | None. | None. | None. |
| Atlanta53 | ″ | 6 | 2 | ″ | ″ |
| Boston53 | ″ | 6 | 2 | ″ | ″ |
| Chicago54 | 2 | 8 | 4 | ″ | ″ |
| Gun-boat No. 154 | None. | 6 | None. | ″ | ″ |
| Gun-boat No. 2 | ″ | 4 | ″ | ″ | ″ |
| Newark | ″ | 12 | ″ | ″ | ″ |
| Baltimore | ″ | 6 | 2 | ″ | ″ |
| Charleston | ″ | 6 | None. | 2 | ″ |
| Miantonomoh | ″ | None. | ″ | 4 | ″ |
| Terror | ″ | ″ | ″ | 4 | ″ |
| Amphitrite | ″ | ″ | ″ | 4 | ″ |
| Monadnock | ″ | ″ | ″ | 4 | ″ |
| Puritan | ″ | ″ | ″ | 4 | ″ |
| Armored cruiser | ″ | 6 | ″ | 4 | ″ |
| Armored battle-ship55 | ″ | 6 | ″ | None. | 2 |
| 2 Gun-boats | ″ | 12 | ″ | ″ | None. |
| 2 Cruisers | ″ | 2456 | ″ | ″ | ″ |
| Floating batteries | ″ | None. | ″ | ″ | 856 |
This gives a total of two 5-inch, one hundred and three 6-inch, ten 8-inch, twenty-six 10-inch, and ten 12-inch. In his last report, Captain Sicard, Chief of Ordnance, states that “for the new ships approaching completion we have eighteen 6-inch, three 8-inch, and two 5-inch guns finished, and three 6-inch and five 8-inch well advanced, together with all the carriages for the Atlanta and Boston, and all for the Chicago, except the 8-inch.... With brown powder the following are the best results obtained in the 6-inch and 8-inch guns.
| Gun. | Powder. | Muzzle Velocity. | Pressure. |
|---|---|---|---|
| Foot seconds. | Tons. | ||
| 6-inch | American Brown. | 2,105 | 15.6 |
| 8-inch | Westphalian Brown. | 2,013 | 15.5 |
“It will be observed,” he adds, “that the muzzle velocities are as high, while the chamber pressures are considerably below those which the guns were calculated to support in service.”
During the preliminary trials afloat of the Atlanta’s battery in July, a few minor faults were unfairly given an importance by the newspapers which led the country to believe that the ship and her armament were useless. Unfriendly critics vented their spite and aired their ignorance in condemnations which included all who had had anything to do, even in the remotest degree, with the design and construction of vessel and gun. Indeed, so bitter and persistent were they that for a time it seemed almost hopeless to expect any further good could come out of the Nazareth of public opinion. It was not a question of politics, for the journalists of every political faith ran amuck riotously upon the subject; nor was it a matter of morals, where, through intelligent discussion, better things could be attained, for with brilliant misinformation and dogmatic dulness each scribe stuck his pin-feathered goose-quill into the navy’s midriff—it being such an easy, such a safe thing to do—and then thanked Heaven he was a virtuous citizen. Finally, a board was appointed to inspect the ship and battery, and after a thorough examination it made the following report:
“In obedience to the Department’s order of the 22d instant, the Board convened on board the Atlanta, Newport, Rhode Island, on the 25th instant (July, 1887), and made a careful examination of the ship, guns, carriages, and fittings, and of the damage sustained during the recent target practice, as reported by the board of officers ordered by the commanding officer of the Atlanta. The Board proceeded to sea on the morning of the 25th instant, but were prevented from firing the guns by a heavy fog which prevailed throughout the day. The ship was again taken to sea on the morning of the 27th instant, and the guns were fired. No deficiencies were noted in the guns themselves other than a slight sticking of the breech-plug in 6-inch breech-loading rifle No. 5 (this disappeared during the firing), some difficulty in the management of the lock of 6-inch breech-loading rifle No. 4, caused by slight upsetting of the firing-pin, and the bending of the extractor in 6-pounder rapid-fire No. 5.
“The recoil and counter-recoil of the 8 and 6 inch guns were easy and satisfactory, except at the second fire of the 8-inch breech-loading rifle No. 1, when the gun remained in. (This was readily run out with a tackle.) The action of the carriage of 8-inch breech-loading rifle No. 1 at the first fire was due to want of strength in the clips and clip circles, and at the second fire to want of sufficient bearing and securing of the deck socket. It is believed that had the deck socket held, the carriage would not have been disabled by the giving way of the clips. The training gear, steam and hand, was uninjured; the gun was readily trained when run out to place. The action of the after 6-inch shifting gun No. 4 was satisfactory, notwithstanding that the front clips had a play of half an inch. The action of the broadside carriages of 6-inch guns Nos. 5 and 18 was satisfactory, except the breaking of clips, the starting of the copper rivets in the clip circles, and the wood screws in the training circles.
“It is believed from the action of the carriage of 6-inch breech-loading rifle No. 5, when the clips were removed, that the carriages can be safety used without clips. The clips, however, give additional security and steadiness to the carriage, and assist the pivot and socket in bearing the shock of the discharge. The firing of the 6-pounder rapid-fire guns developed a weakness in one leg of the cage mount of No. 4, due to imperfect workmanship, and showed also the necessity of locking nuts on the bolts that secure the mounts to the ports. The tower mounts of the 3-pounder rapid-fire guns are unsatisfactory. They cannot be moved with facility; the line of sight of the gun is obstructed at ranges beyond 1600 yards, and the guns cannot be safely used as now fitted. For this reason 3-pounder rapid-fire No. 3 was not fired. The tripod mounts of the 1-pounder rapid-fire guns need stronger holding-down arrangements. The tower mounts of the 47-millimetre revolving cannon are like those of the 3-pounder rapid-fire guns, and have the same defects. The mounts of the 37-millimetre in the tops are satisfactory.
“Careful observation of the effect of the firing upon the hull of the vessel failed to develop any damage other than the breaking of the cast-steel port-sills and the starting of some light wood-work. The shock of discharge was slight on the berth-deck, and observers there were unable to observe which 6-inch gun had been fired. The deck, hull, and fittings, with the exception of the port-sills, hinges to superstructure doors and vegetable lockers, and some of the light wood-work, have every appearance of strength and ability to endure the strain of continuous firing of the guns. The blast of the forward 8-inch gun, when fired abaft the starboard beam, will not permit the crews of the starboard 3-pounder rapid fire and 1-pounder rapid fire to remain at their guns. When the after 8-inch gun is fired forward of the port beam, the crews of the after 47-millimetre revolving cannon and of the port after 1-pounder rapid fire cannot remain at their guns. When the forward 6-inch shifting gun is fired on the port bow or directly ahead, the crew of forward 8-inch gun cannot remain at their places. When the after 6-inch shifting gun is fired on the starboard quarter or directly aft, the crew of the after 8-inch gun cannot remain at their gun. The inability to fire parts of the secondary battery under certain conditions is due to the great arc of fire given to the 8-inch guns. This can hardly be called a defect. It is thought that a screen can be placed between the 8 and 6 inch guns which will enable them to be worked together forward or aft.
“The pivot socket of the 8-inch carriage should have a broader bearing surface, and should be rigidly bolted to the steel deck and to the framework of the ship in such manner as to distribute the strain over a larger area. The clips and clip circles of the 8-inch and 6-inch carriage should be made of steel. The clips should have larger bearing surfaces, and should be shaped to fit the circle. The circle should have double flanges, and be bolted (not riveted) on each flange to the steel deck. There should be no appreciable play between the clips and the circles. All bolts used in the battery fittings should have the nuts locked.
“The clip rail of the tower mount should be altered to fit the mount. This change will make the compressors effective, and allow the guns to be used with safety. The port-sills should be replaced by heavier sills, made of the best quality of malleable cast-steel. The plan of testing the hull, guns, and fittings of the Atlanta arranged by the Board contemplated a more extended use of the main battery, but the weakness developed in the port-sills and in the sockets of the 8-inch carriages rendered further firing inadvisable.”
Whatever conclusion may be drawn from this report, there is one fact which may serve as an important corollary. In the latest drills of the ships on the North Atlantic station, the Atlanta won the champion pennant for the best gunnery practice, and this with guns and carriages which were said to be completely disabled.
The safe employment of high explosives for war purposes is looked upon by many as a solution of certain vexed problems, and much time and money have been given to the subject. From the nitro-glycerine products there has been a loudly heralded advance to melinite and roborite, of which the great things expected have not yet been realized. Among the most promising attempts to use dynamite in a projectile is that made with the pneumatic gun, perfected by Lieutenant Zalinski, of the U. S. Artillery, who has courteously furnished the following description of the system:
“The pneumatic dynamite torpedo gun is a weapon which has been evolved for the purpose of projecting with safety and accuracy very large charges of the high explosives. While a gun in name and form, it is practically a torpedo-projecting machine, the propelling force used being compressed air. The use of the compressed air gives uniformity and complete control of pressures and total absence of heat. This insures entire absence of violent initial shocks from the propelling force; it also eliminates danger of increasing the normal sensitiveness of the high explosives by heating while resting in the bore of the gun. The ability to reproduce, time after time, absolutely the same pressure necessarily carries with it great accuracy of fire. The torpedo shell thrown by the gun is essentially arrow-like, and is very light and compact compared to the weight of charge thrown. This is a matter of no little importance on shipboard, as a very much larger number can therefore be carried for a given weight and storage room. The torpedoes projected by this machine have a twofold field of action when acting against ships: first, the over-water hull, second, the under-water hull.
“The shell is exploded by an electrical fuse. This is brought into action if striking the over-water hull an instant before full impact. If the shell misses the over-water hull and enters the water, explosion is produced after the shell is thoroughly buried, thus obtaining the fullest tamping effect of the water. The delayed action of the fuse can be controlled so as to cause the shell to go to the bottom before explosion ensues. This is needed at times when the torpedo shell is used for counter-mining a system of submerged stationary torpedo defences.
“Experiments against iron plates have shown that it is essential to have the initial point of explosion at the rear of the shell. When explosion takes place by simple impact from the front end, the injury to the plates is actually less than when a blank shell is used.
“For these reasons the fuse has been arranged so that the initial point of explosion is at the rear of the shell. No attempt has been made to make a shell which can perforate armor before explosion. To do so would involve thickening the walls to such an extent as to materially reduce the weight of the charge carried. Besides that, it is very doubtful whether a shell fully charged with gunpowder can perforate any considerable thickness of armor without previously exploding its bursting charge. Much more will this be the case where the bursting charge is one of the more sensitive high explosives.
“The pneumatic torpedo-gun system has various fields of usefulness as an auxiliary war appliance. Among these are the following:
“1st. On swift-moving torpedo-boats; 2d. On larger war-vessels, for general use and for defence against surface and submarine torpedo-boats; 3d. In land defences; 4th. For use in the approaches during land sieges.
“Torpedo-boats carrying the pneumatic guns can commence effective operations at the range of at least one mile, as compared to not more than three hundred yards of the boats carrying the Whitehead torpedoes. Their torpedo shell cannot be stopped by netting, as is the case with the latter. The charges which can be thrown are also much greater. The guns to be carried on the pneumatic dynamite-gun cruiser now building for the United States government will throw shell charged with 200 and 400 pounds of explosive gelatine. These guns can be fired at the rate of one in two minutes, and indeed even more rapidly if required.
“In the defence of a man-of-war no other means can as effectually stop the advance either of submarine boats or submerged movable torpedoes. This is due to the ability to explode the large charges when the shells are well submerged. Their radius of action will be so great as to avoid the necessity of making absolute hits. The chances of stopping the attack are thereby very much increased.
“A tube of large calibre can be fixed in the bow, so as to be of use when advancing to the attack with the ram. An 18-inch shell, containing 1000 pounds of explosive gelatine, can be thrown 500 yards in advance of the ship, and that, too, without danger of running into the explosion of its own petard, as would be the case in ejecting directly ahead ordinary torpedoes. This will be made more clear by the statement of the relative speed of the two classes. The pneumatic-gun torpedo has a mean velocity of 400 knots for a range of one mile, as compared to 25 knots for a range of 200 yards of the Whitehead torpedo. Furthermore, there is no danger of the shell turning back, as is sometimes the case with the latter.
“The opportunities of making an effective hit will be much greater with the torpedo shell than with the ram; it will be easier to point the vessel fairly at the enemy’s broadside when at the range of five hundred yards than to bring the ram in absolute contact with the enemy’s side. The gun-tubes used are very thin (not exceeding three-quarters of an inch in thickness), and may be of sections of any convenient length. The other portions of the supporting truss, reservoirs, etc., are also of comparatively light weight. They could be of large calibres, and the destructive effects producible by large charges of high explosives will doubtless have a demoralizing effect upon the defence.”
Upon September 20th of this year a public trial was successfully made with the gun, the target being the condemned coast survey schooner Silliman. After firing two shots to verify the range, the gun was loaded with a projectile which was five and a half feet in length, contained fifty-five pounds of explosive gelatine, and was fired under an air pressure of 607 pounds. The torpedo rushed from the muzzle of the tube with a loud report; in thirteen seconds it plunged into the water close under the starboard quarter of the Silliman, and exploding almost instantly, threw a great volume of water one hundred and fifty feet into the air.
For a moment the schooner was hidden from view, but when the mist cleared away it was found that her main-mast had toppled over the side. At a distance this seemed to be all the damage inflicted, but a closer inspection showed that all the wood-ends on deck had been loosened, that the cabin fittings had been thoroughly shaken up, and that water was running into the hold.
Soon afterwards a fourth shot was fired. This landed very close to the starboard side of the vessel, and on explosion seemed to lift the Silliman out of the water.
The hull was very badly shattered; the water-tank, which had been firmly fastened to the schooner’s bottom, was blown up through the deck and floated on the wreckage, and the stump of the main-mast was capsized. The bow was held above water by barrel buoys, and the fore-mast, which had heeled over to an angle of forty-five degrees, was sustained by the steel rigging that had become entangled in the pieces of wood floating to windward.
MACHINE AND RAPID-FIRE GUNS.
Of the machine guns, the Gatling, Gardner, Nordenfeldt, and Maxim systems are the best known. The adoption of the Accles feed in the Gatling eliminates largely the liability of cartridge jams, and increases the rapidity of fire at all angles to twelve hundred shots per minute; when this rapid delivery of fire is not needed, Bruce’s slower feed may be substituted. The Gardner gun is an effective weapon, but it has less rapidity of fire and smaller range of vertical train than the Gatling. The Nordenfeldt rifle-calibre gun has not obtained the prominence of the others, and the Maxim, in which the energy of recoil is ingeniously applied to the work of loading and firing, is growing in favor. The Hotchkiss revolving cannon was a wonderful step—the 37, 47, and 53 millimetre calibres firing 1 pound, 2½ pound, and 3½ pound explosive projectiles, with muzzle velocities of about 1400 feet per second. “The heavier nature of revolving cannon,” declares Commander Folger, United States Navy, “proved somewhat unwieldy, and the change to the single barrel of increased length, and using a heavier powder charge, was a natural one, and in keeping with the growing ballistic power of large guns. Though no longer denominated machine guns, the term now being generally applied to a cluster of barrels, the rapid-fire guns are a direct outgrowth of the larger calibres of machine guns, and are classed with them as secondary battery arms. There are now in the service of all the great military powers rapid-firing guns of 47 and 57 millimetre calibre, firing respectively explosive shells of 3 pounds and 6 pounds weight, at muzzle velocity of about 1900 feet per second. This will give with the 6-pound gun a range of about 2½ miles at 10 degrees elevation. These guns will deliver, under favorable circumstances, perhaps ten aimed rounds per minute, and the shells perforating the sides of an unarmored vessel, and bursting, after passing through into, say, twenty-five fragments, each with energy sufficient to kill a man, we have here a weapon of unequalled destructive capacity. It is beyond question that the conditions of combat between ships and forts are definitely changed by the advent of these guns. Even armored vessels with covered batteries are at a disadvantage, as a hail of missiles will seek the gun-ports and conning-towers wherever an enemy, from the nature of circumstances, takes close quarters. Experiment abroad has also demonstrated that the projecting chase (forward body) of a large gun is extremely vulnerable, and liable to injury from the fire of the larger rapid-firing pieces.
“This system, which is just now so important an adjunct to the main battery of ships of war, is of but recent development. The first order received for a weapon of this kind by the Hotchkiss firm came from the United States, and the guns now mounted in the new ships Boston, Atlanta, and Dolphin were delivered under it. Three calibres were obtained, viz., the 6, 3, and 1 pounder, as they are known in the United States navy, their usual names in other countries being the 57, 47, and 37 millimetre guns. Since their introduction the demand for larger calibres by most of the prominent naval powers has been so pressing that the Hotchkiss Company has produced a 9-pounder and has a 33-pounder in course of manufacture. It is believed that this last calibre represents about the limit of utility of the Hotchkiss system, though the gain in time by the use of ammunition carrying the charge projectile and fulminate in one case will recommend it for use with much larger calibres, even where two men may be required to handle the cartridge.”
The most important trials of rapid-fire guns during the past two years are thus described by Lieutenant Driggs, United States navy:
“The various systems now in use, or being developed, are the Albini, Armstrong, Driggs-Schroeder, Gruson, Hotchkiss, Krupp, Maxim, Nordenfeldt. Of these the Armstrong has not been favorably received on account of the cumbersome breech-closing arrangement. This consists in two side levers attached to and turning about the trunnions; a cross-head connects the two levers, and by an eccentric motion one of them is pressed against or removed from the breech of the gun, thus closing or opening it. The Bausan has two of those guns, but with that known exception few, if any, have been put in service.
“The Gruson gun is said to be very similar to the Hotchkiss in its mechanism, though not as good. The Maxim and Hotchkiss are both well known. The Nordenfeldt, which in Europe is the greatest rival of the Hotchkiss, is entirely different from the guns heretofore made under this name. In the single-shot rapid-fire gun the breech is closed with a double breech-plug, which is revolved in the breech recess by a cam motion. The plug is divided transversely; the front half carries the firing-pin, and has only a circular motion in closing and opening; the rear half acts as a wedge, the first motion being downward and the second circular, the front half then moving with it.
“One of the most complete tests to which guns of this class have been subjected was that conducted by the Italian government in February of last year (1885). The trials were made at Spezia, the following being offered for test: Hotchkiss rapid-fire; improved Nordenfeldt rapid-fire on recoil-carriage; Armstrong rapid-fire; and a rapid-fire gun made at the Government Works at Venice. The Armstrong gun was not fired; the others were fired in the following order: Nordenfeldt, Hotchkiss, and Italian.
“The guns were mounted on board a small ship (the Vulcano) for firing at sea. A large target was fixed on the breakwater in the middle of the harbor of Spezia, and two smaller targets of triangular shape had been anchored, one 550 yards inside, and the other 550 yards outside, the breakwater. The Vulcano was then placed 1300 to 1400 yards inside the breakwater, and fire begun against the large target with the Nordenfeldt 6-pounder gun, which was worked by Italian sailors. A first series of eighteen shots were fired in forty-seven seconds, for rapidity of fire with rough aiming. A second series of sixteen shots were fired in thirty-four seconds. The rapidity of fire with rough aiming and untried men was thus respectively at the rate of twenty-three and twenty-eight shots per minute. Afterwards, ten case-shots were fired with the gun almost level, in order to see how the lead bullets were spread over the range. Some of them were seen to touch the water 700 or 800 yards from the muzzle, and the whole range was well covered by the 150 lead bullets contained in each of the Nordenfeldt case-shots.
“The second part of the programme consisted of the firing at three targets, respectively at 600, 1200, and 1800 yards, the ranges being only approximately known, changing the aim at every third shot, and firing under difficulty, owing to the movement of the ship. Twenty-one common shells were fired, seven at each target, with good accuracy, and the shells on striking the water burst better at the shorter than at the longer ranges.
“The firing at sea was closed with one more series of ten rounds, fired rapidly in twenty-six seconds, in order to see if the gun would act well after being heated by the eighty-five rounds which had already been fired. Four of the last series were ring-shells, and burst on striking the water at the first impact, breaking into a larger number of pieces than the common shells. The Nordenfeldt gun was then mounted on shore for tests of penetration. The plates used were: (1) a 5¼-inch solid wrought-iron; (2) a 4-inch solid (Cammell) steel plate; (3) one ⅞-inch steel plate, at an angle of fifteen degrees to line of fire. The two thick plates were backed by ten inches of oak, and at right angles to line of fire and one hundred yards from the gun. The perforation was in every case complete, both with solid steel shot and chilled-point shells, these latter bursting in the wood behind. The thin plate was then put at more acute angle to the line of fire, and only when this angle was seven degrees or eight degrees did the projectile fail to penetrate. The indicated muzzle velocity of this gun is 2130 feet, with a 6-pound projectile and charge of two pounds fifteen ounces.
“A few days afterwards the Hotchkiss gun went through the same trials and programme. For rapidity forty rounds were fired with rough aiming in three minutes, the rate being 13.3 per minute. The shooting was good, but the men serving the gun complained of being fatigued by the shocks from the shoulder-piece. The muzzle velocity was about 1085 feet, or about 300 feet below that of the Nordenfeldt. Last of all, the Italian gun was fired, but as it was designed for 1480 feet velocity, it was not brought in direct competition with the other two guns in power. The rapidity of fire obtained, however, was about twenty rounds per minute, and both the mechanism and recoil-carriage worked well.57
“The Hotchkiss and Nordenfeldt guns were tried in competition at Ochta, near St. Petersburg, in September last (1886). The reports that have reached this country are very meagre, but are unanimous in favor of the Nordenfeldt gun. From what can be learned, the fire was first for rapidity, in which the Nordenfeldt discharged thirty rounds in one minute, and the Hotchkiss twenty rounds in the same time, the initial velocity of the former being 624 metres (2047 feet) per second, while that of the latter was 548 metres (1797 feet) per second.
“The fire of both guns was directed upon a target at 1800 metres (1969 yards) range. The Nordenfeldt scored nine hits, while the Hotchkiss made none. It is more than likely that this failure was due more to defective pointing than to any defect of construction.
“The trial closed with a very interesting and instructive experiment.
“Four targets were placed at 600, 800, 1000, and 1200 metres; each gun was to fire as rapidly as possible for thirty seconds, changing the range each fire, from the 600 up to the 1200 metre target and back. During this test the Nordenfeldt is said to have discharged fifteen shots in the thirty seconds, and to have made nine hits, while the Hotchkiss scored but two hits and only discharged eleven rounds in thirty-two seconds. Here again the element of inaccurate sighting may be largely responsible for the difference in the number of hits, but the great disparity in the number of rounds fired must be due to the mechanical defects in the Hotchkiss system by which the action of its breech-block is too slow. Notwithstanding the reported success of the Nordenfeldt gun in the trials, the Russian government ordered a number of Hotchkiss guns and no Nordenfeldts.”
The latest experiments with large calibred rapid-fire guns were those of the Armstrong 36 and 70 pounder. The first piece differs materially from the new 33-pounder Hotchkiss; it is 4.724 inches in calibre, 14 feet 2½ inches length, and weighs 34 hundred-weight. It was fired with seven and a half pounds of powder ten times in forty-seven seconds, or at a rate six times faster than that obtained with the service guns of like calibre. The 70-pounder was fired with both twenty-five-pound and thirty-pound charges, at a speed of from eight to ten rounds per minute. In the latest mount for the 36-pounder the gun is supported on a rocking slide which pivots on transverse bearings, so that the piece moves only forward and backward on the slide; elevation and depression are given by a shoulder-piece attached to the slide, and the gun is secured at any desired angle with a clamp attached to the side of the slide.
This development of rapid-fire pieces opens anew the discussion as to the comparative values of large and small calibre guns. At the present stage of the question it is safe to say that, however necessary the large calibre may be in armored battle-ships and coast-defence vessels, its usefulness in thin-skinned, high-powered cruisers is questionable. Abroad, the long-range guns which constitute the primary batteries are being reduced in calibre, while the secondary batteries of rapid-fire guns are increasing so much in size that before the next sea-war a nearly uniform calibre of four or five inches will probably be established.
The reasons for these changes are not difficult to understand. In all sea engagements hereafter type will fight with type; that is to say, apart from the rôle which auxiliary rams and torpedo-boats may play, armored ships will oppose armored ships, and unarmored cruisers and gun-boats will, when intelligently handled, seek action only with vessels of similar character. To-day every unarmored ship afloat or under construction can be penetrated at the average fighting distance by a musket-bullet impelled with a little more than the ordinary velocity; and as there is absolutely no protection, it seems a mistake to arm such vessels with the unnecessarily large calibres now in use. Especially is this true when their employment is based mainly upon the remote assumption that such ships may have to attack fortifications. Smaller guns will do the work equally as well, if not better; for the greater intensity of fire secured by the certain action of a large number of easily handled small-calibred guns is surely more valuable than any probable advantage which might be derived from heavier projectiles fired under conditions that make their effectiveness doubtful.
Whatever may be said to the contrary by mere theorists, the difficulty of handling ordnance increases enormously as the calibres grow; and sea-officers, who alone are the proper judges, insist that the monster pieces of the present day are so unmanageable as to be nearly useless. Of course, where armor penetration is vital to success, heavy armaments must and will be employed; but when this factor need not be considered, a great many light guns, easily worked by hand, are the demands of the hour. The problem, fortunately, is nearer solution owing to the development now in progress; and when this is coupled with the rapidly increasing popularity of the 5-inch breech-loading all-steel rifle, our country notably may congratulate itself that ordnance is reverting to a plane which other nations mistakenly and at great cost abandoned, and which the United States can readily attain.