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the wabbling. If the flight were long enough this center of gyration would eventually get to the center of gravity, and the shell would certainly tumble.
The XI inch gun was not converted into a breech loader, for the reason that it is mainly designed for use in our present cruising vessels as a shifting pivot gun for spar decks, and there would be little if any advantage gained from rapidity of fire or convenience in loading. The cost of conversion in that case, and we must keep the cost in view, for reasons already given, would be as great as that of a new gun better adapted to breech loading. The army X inch gun is, from its form, better adapted for a breech loader, but either is but a make-shift."
Among those who have had much to do with converted guns of this kind there are many warm advocates of building new guns on the Pallisser system. Experimental guns of 12.25 and 10 inch caliber have given very good results at Sandy Hook; and if, as has been stated in reports of the recent experiments of Krupp at Meppen, the pressures did not in any case exceed twenty tous while producing the wonderful results obtained there, there is no reason why we should not reproduce these velocities and energies, by casting a gun long enough to burn to advantage an equally good powder from an enlarged chamber, and using our system of rifing and projectiles.
The next gun to be taken up is the converted Parrott, where the caliber of the original gun is not changed, and, besides being strengthened in the manner so much used by the French, by inserting a short steel tube from the rear, it becomes a breech loader.
The first 100 pdr. Parrott converted had a long jacketed tube inserted from the rear and secured at rear, and front ends by collars similar to the muzzle collar of the 8 inch Rifle. A second gun was converted by inserting a tuhe of tough steel from the rear to about one foot in advance of the vertical plane of the trunnions. The old rifling was kept on along the tube. In this case the tube was screwed into the cast irou casing left-handed, so that the tendency of the rifled motion would be to tighten it. These guns were made breech loaders on the slotted screw system,-so much used by the French that it is often called the French or Reffye system.
The strength of the gun is certainly increased by this conversion, and by consulting the report of the Secretary of the Navy for 1878 we find in the range tables that the power and efficiency of the gun is practically the same with the present service charges.
Quite a number of 100 pdr. Parrotts have been converted on this principle into 80 pdr. B. L. R. and 60 pdr. Parrotts into 60 pdr. B. L. R. Besides this, sample guys of 30 and 20 pdrs. have been converted. I think the great advantage to the navy in this conversion of Parrott guns lies in the knowledge we gain by working up the subject of breech loaders. So far it has always been with the slotted screw system, which, while often called the French, is, in conception, purely American. To the French belongs the credit of developing and applying it, and, in their service firing, of more than sixty thousand rounds, with heavy guns of from 42 to 16 centimeters, they have had no accidents attributable to the system.
This system was patented in this country by B. Chambers, of Washington, in 1849, and tested in 1851 in a 12 pdr. smooth bore with fixed metallic cartridges, center primed with a percussion cap. It worked sufficiently well to suggest further trials, which were reconmended by Commodore Morris, then Chief of the Bureau of Ordnance, but the suggested experiments were not carried out, on account of the expense, and for the reason, too, that an efficient system of muzzle-loading guns (Dahlgren) had just been introduced. This system was next taken up and worked out in France in 1859 by Colonel Treuille de Beaulieu, and the most advantageous form, diameter, length, and pitch of screw worked out by actual experiment. No slotted screw has ever failed by stripping, even when more than half of the threads have been purposely removed.
There are arguments in favor of either a large or small diameter of breech plug, but, as a matter of fact, neither the Reffye, with a very large screw, nor the De Barge, with a very small screw, nor the Bureau of Ordnance regulation, which is medium, has ever failed, though in extreme proof the whole breech has been blown
The army ordnance has had converted, at the works of the South Boston Iron Company, a X inch columbiad into an 8 inch B. L. R., on the sliding wedge system of Krupp, which has given great satisfaction, but the slotted screw mechanisni would seem to have advantages over it, for these reasons: In small guns, by having folding handles, all the breech mechanism can be concealed within the breech; it is readily examined after every fire, and, each part being in plain view, is easily wiped out; admits of the cup gas check which gives the best seal and reduces the area on which gas pressure acts, and is cleaned during loading. It does not require so accurate an adjustment, does not so easily get out of order, and spare parts can be easily substituted.
I learn from the Inspector of Orduance at Cold Spring that the 80, 60, 30 and 20 pdrs, which he has prored worked perfectly, and were loaded with the greatest ease and rapidity.
There is nothivg to be said about the steel 3 inch B. L. Howitzer that is not good. It is now being issued to all vessels fitting out, and gives great satisfaction as to strength, range and accuracy. It is moreover very light, is easily loaded and taken care of, and with the proposed improvements of the cup gas check, and a straight, perpendicular rent, will equal if not excel any arm of its kind. Before being issued for service these guns are bronzed by a process of successive oxidations, which when finally burnished gives them a color resembling rosewood, and a polished surface that will resist the friction of coarse emery paper, while the coating is supposed to have a penetration of .005 of an incb.
The projectiles used in the larger rifles are of the patterns known as Parrott and Butler, and as their difference lies mainly in the expanding band, are essentially of the same type, the rifled motion in each case being given by the expansion of the soft composition band into the grooves of the gun. Either form efficiently rotates the projectile, but, as in the Butler patent the annular groove in which the gas acts also tends to make the band grip the base of the shell all the tighter. I am in favor of it as being safer in firing over boats or the heads of troops. At the Sandy Hook experiments these projectiles have given entire satisfaction, and the system has been practically adopted by the army.
The subject of projectiles is an extremely important one and should be considered in connection with the system of rifling. The Parrott projectile and rifling combined were in advance of their time as was the Rodman invention of prismatic powder, and it is now, in the light of later experiments in Europe, safe to say that with liberal appropriations to conduct experiments with them we should have maintained our lead over European nations in ordnance.
We were certainly well in advance in powder manufacture under the direction of the Bureau of Ordnance up to 1874, when the money for further experiments was not forth-coming, and the Italians came to the fore with their Fossano powder, while the useful development of the Rodman prismatic powder by the Germans and English continued. In England, while the authorities cling to the depraved system of studded projectiles with the same illiberal tenacity that led them to give up further trials with breech loaders, and rest their cause upon muzzle loading guns; we yet see that they are using a gas check to prevent the rush of gas along the groove with its consequent waste of power and scoring up of the gun. They have had great trouble in keepivg these gas checks from flying wild as the projectiles leave the gun, their tendency to whirl to the left of the line of fire being decidely objectionable. It seems strange that the gas check which is now of so much trouble to them, and only produces one effect in the gun, should not be used as is ours to accomplish the rotary motion as well. Even their grooves are getting quite numerous, as we find in the projectiles for the 38, 35 and 25 ton guns nine rows of studs. It takes surprisingly litile force simply to rotate a projectile, and I venture to say one of our shells would be rotated in these guns by the mere expansion of the band and without studs. In a breech loading gun the same shell may
be used, but here we have a chance to prevent the shell's sliding forward in the bore, by depression of gun or shock in running out, by having a slightly enlarged chamber with a flare or shoulder to the band, or te may use a forced projectile such as that of the 3 inch B. L. H. There are many varieties of forced projectiles of greater or less merit. A devise used for rotating at the recent experiments at Meppen ras essentially that patented in England by Blakely, and consists of copper wires with protruding semi-circular section, forced into groores at the rear end of the shell, with one or more for centering towards the forward end of cylinder. That used by Col. Crispin at Sandy Hook in the 8 inch B. L. R., has a band like that for projectiles for the M. L. R., and except that at the extreme rear it has a very slight shoulder. A few blows with a hammer to flare out the lip would accomplish the same thing and take away the forcing character. A forced projectile is used in the 3 inch B. L. H., the band being well forward towards the center of gravity, and to prevent ballotting a centering band has to be used at the rear. This balloting of elongated projectiles is a subject deserving of a good deal of attention, as it pounds on and scores up the bore besides giring an imperfect flight-it may also to a certain extent act in a wedging manner. From experiments made in this country, and notably from the proof firing at Sandy Hook, it would seem that projectiles efficiently rotated from the rear, and where, as in the Butler and Parrott, the windage is not entirely suppressed, are free from balloting and the question naturally comes up why this should
The owners of the Butler patent claim that at discharge the quick motion of rotation, caused by the expansion of gases and the driving forward of the projectile, throws the shell up into the axis of the bore and spins it after the manner of the gyroscope, at the same time windage not being entirely suppressed, the gases at great pressure (to which the mere weight of the shell is as nothing) surround it and keep it up. However this may be, judging from the flight of this projectile, balloting does not take place; yet in the case of soft coated projectiles where the band shows rifle motion to have been well taken up, the inference from a fluttering flight is, length of shell and pitch of rifling being good, that there has been balloting.
There is now being constructed at South Boston, under my inspection, and it is neariug completion, a 9 inch B. L. R. couverted from a 10 inch Parrott, by inserting a jacketed steel tube from the rear.
The long inner tube is made of very low ductile steel, being in fact homogeneous iron rather than steel, and has walls two inches in thickness, while the steel jacket is cousiderably higher in carbon, giving it greater tensile strength and elastic limit. A shallow thread on the jacket keeps the tube in from the rear and a muzzle collar secures the front end. The breech mechanisın is the slotted screw principle, and although the breech plug could be easily withdrawn by handles as is the plug of the 80 pdr. B. L. R., still, on the Bureau principle of working up on smaller things the attachments that will be needed on larger, a quick pitch screw in the box of the plug tray works the plug in and out, while the plug is turned the 60° necessary to lock and unlock it by double gearing. The Broadwell ring is used in this gun, in preference to the cup gas check, to allow pressure gauges to be set into the nose plate of the breech plug, as this gun is likely to be used for testing powder for rifled guns. The old reinforce band is left on over the breech, and, to compensate for throwing forward the center of gravity and to retain a breech preponderance, the old trunnions have been cut off and a cast iron trudnion band, with center of trunnions three inches forward of old center, shrunk on. This band is not a strengthening reinforce, but merely a strap to hang the gun in, yet it has the effect of rendering the gun much more shapely.
Another gun is to be made entirely of steel at the same works, the steel being furnished by the Nashua steel works. It is to be a 6 inch B. L. with an enlarged chamber of 8 inches, and very long. The long tube or gun proper will be of milder steel than the jacket, breech band and reinforce rings, which are to be of very high tensile strength and elasticity. This gun will doubtless reproduce the great velocities obtained by Armstrong with his chambered gun of this caliber.
It is too often said by unthinking people that it is needless to go on with experiments which are necessarily so expensive, and to build guns that will, in all probability, be out of date in a very few years,