Friedrich Engels

Rifled Cannon

Written March/April 1858.

From the English.

[*New York Daily Tribune*, No. 5914, April 7, 1860]

I

The first attempts to increase the range and accuracy of guns by cutting grooves in the bore, thereby giving the projectile a rotation perpendicular to its line of flight, date from the 17th century. In Munich there is a small cannon with a rifled barrel, made in Nuremberg in 1694; the barrel has eight grooves and a calibre of about two inches. Throughout the 18th century experiments were carried out with rifled guns in both Germany and England, some of them breech-loaders. Although only small calibres were involved, very satisfactory results were obtained. The English two-pounders of 1776, with a range of 1,300 yards, gave a lateral deviation of only two feet – a degree of accuracy which no other firearm of that period could even remotely match. In the same year these rifled guns were used for the first time to fire elongated projectiles.

However, these experiments remained for a long time without any practical result. The military views of the time were entirely opposed to rifled arms. Even the rifle was then a very clumsy instrument, loading being a lengthy and laborious operation that required considerable manual skill. In an age when rapid fire, whether from deployed lines, the heads of columns or skirmishers, was one of the chief requirements of battle, it was a weapon unsuitable for general warfare. Napoleon tolerated no rifled weapons in his army; in England and Germany only a few battalions were armed with them; only in America and Switzerland did the rifle remain a national weapon.

It was the Algerian war that again brought the rifle into credit and led to the improvement of its construction; these improvements were only the beginning of that immense revolution in the whole system of firearms which is even now far from being complete. The smooth-bore muskets of the French could not compete with the long *espingardas* of the Arabs; their greater length and better material, which permitted a heavier charge, enabled the Kabyles and Bedouins to fire on the French from a distance at which the regulation musket was completely ineffective. The Duke of Orleans, who had seen and admired the Prussian and Austrian chasseurs, organised the French chasseurs on their model, who, in respect of armament, equipment and tactics, soon became the best troops of their kind in the world. The rifle with which they were armed was many times superior to the old rifle and underwent further modifications which finally led to the general adoption of the rifle by the entire infantry of Europe.

Thus after the range of infantry fire had been increased from 300 to 800 and even to 1,000 yards, the question arose whether field artillery, which had hitherto commanded all distances from 300 to 1,500 yards, would still be able to hold its own against the new small arms. In fact the greatest effectiveness of ordinary field guns lay precisely in that range which was now also attained by the rifle; case shot was hardly effective beyond 600 or 700 yards. The solid shot of the six- and nine-pounders gave no very satisfactory results beyond 1,000 yards, and in order to be decisively effective, shrapnel shells (spherical case) required coolness and accurate estimation of distances – qualities not always to be found on the battlefield when the enemy advances; the shell fire of the old howitzers against troops was, moreover, anything but satisfactory. Armies such as the British, which had the nine-pounder as its smallest calibre, were still best off; the French eight-pounder and still more the German six-pounder became almost useless. To remedy this, the French, about the beginning of the Crimean war, introduced Louis Napoleon’s so-called invention, the light twelve-pounder, *canon obusier*, from which both solid shot, with a reduced charge amounting to only a quarter of the weight of the projectile instead of a third, and shells could be fired. This cannon was merely an imitation of the English light twelve-pounder, which had already been given up again by the English. The system of firing hollow projectiles from long guns had long been in use in Germany, so there was absolutely nothing new about this supposed improvement. Nevertheless, arming the whole French artillery with twelve-pounders, even with reduced range, would have given it a decided superiority over the old six- and eight-pounders. To counter this, the Prussian government resolved in 1859 to equip its entire foot artillery with heavy twelve-pounders. This was the last step in the development of the smooth-bore gun; it showed that the whole affair was settled and the defenders of the smooth bore had been reduced *ad absurdum*. Indeed, nothing could be more absurd than to arm the whole artillery of an army with these clumsy, unwieldy Prussian twelve-pounders, and that at a time when mobility and speed in manoeuvring are the most essential requirement. Since the light French twelve-pounder possessed only a relative superiority over other artillery but none whatever over the new small arms, and the heavy Prussian twelve-pounder was a palpable absurdity, nothing remained but either to abandon field artillery altogether or to adopt rifled guns.

Meanwhile, experiments with rifled guns had been steadily continued in various countries. In Germany the Bavarian Lieutenant-Colonel Reichenbach had already experimented in 1816 with a small rifled cannon and a cylindro-conoidal projectile. As regards range and accuracy the results were very satisfactory, but difficulties of loading and obstacles not inherent in the matter itself frustrated the continuation of the experiment. In 1846 the Piedmontese Major Cavalli constructed a rifled breech-loader which attracted considerable attention. His first gun was a thirty-pounder, loaded with a cylindro-conoidal hollow projectile weighing 64 pounds and with 5 pounds of powder. At an elevation of 14 3/4 degrees he obtained a range (measured to the first graze) of 3,050 metres, that is, 3,400 yards. An important result of his experiments (carried on up to the latest period partly in Sweden, partly in Piedmont) was the discovery that all projectiles fired from rifled guns have a regular lateral deviation caused by the angle of the twist, always towards the side towards which the grooves run. Once this was established, Cavalli also invented the so-called lateral or horizontal tangent scale for

correcting the deviation. The results of his experiments were most satisfactory. At Turin in 1854 his thirty-pounder, with a charge of 8 pounds and a projectile weighing 64 pounds, gave the following results:

| Elevation | Range | Lateral irregular deviation |
|-----------|-------|-----------------------------|
| 10°       | 2,806 m | 2.81 m                      |
| 15°       | 3,785 m | 3.21 m                      |
| 20°       | 4,511 m | 3.72 m                      |
| 25°       | 5,103 m | 4.77 m                      |

That is, at 25 degrees elevation a range of over 3 miles is obtained with a lateral deviation from the line of sight of less than 16 feet (after correction by means of the horizontal tangent scale)! The largest French field howitzer, at a range of 2,400 metres, equal to 2,650 yards, had lateral deviations averaging 47 metres or 155 feet – thus ten times greater than that of the rifled gun at twice the range.

Another system of rifled guns which attracted attention a short time after Cavalli’s first experiments was that of the Swedish Baron Wahrendorff. His gun was likewise a breech-loader and his projectile cylindro-conoidal. The difference in the projectile consisted, however, in the fact that Cavalli’s projectile was of hard metal and had studs that engaged in the grooves, whereas Wahrendorff’s projectile was coated with a thin lead jacket and was slightly larger in diameter than the calibre of the rifled part of the bore. After the projectile had been inserted into the chamber, which had the appropriate size for this purpose, the explosion drove the projectile into the rifled barrel; the lead, being pressed firmly into the grooves, eliminated all windage and prevented the escape of even the smallest amount of the gas generated by the explosion. The results obtained with these guns in Sweden and elsewhere were thoroughly satisfactory, and while Cavalli’s guns were adopted in the armament of Genoa, Wahrendorff’s guns played a part in the casemates of Waxholm in Sweden, Portsmouth in England, and in some Prussian fortresses. Thus the introduction of rifled guns into practice had begun, although only for fortresses. Only one further step remained – to introduce them into the field artillery – and that has been done in France and is now being done in all European

artilleries. The different systems according to which rifled field guns are now being successfully developed, or can be developed, shall be the subject of a further article.

[*New-York Daily Tribune*, No. 5926, April 21, 1860]

II

As we said in the previous article, the French were the first to introduce the rifled gun into practical warfare. For five or six years two officers, Colonel Tamisier and Lieutenant-Colonel (now Colonel) Treuille de Beaulieu, had been experimenting in this field on behalf of the government, and the results obtained were found sufficient to serve as the basis for a reorganisation of the French artillery just before the outbreak of the last Italian war. Without going into the history of the experiments, we shall at once proceed to a description of the system now adopted by the French artillery.

In accordance with that desire for uniformity so characteristic of the French, they adopted for the field artillery only one calibre (the old French four-pounder with a bore diameter of 85 1/2 millimetres or nearly 3 1/2 inches) and one for the siege artillery (the old twelve-pounder of 120 millimetres or 4 3/4 inches). All other guns, with the exception of mortars, are abolished. The material employed is generally ordinary gunmetal, but in some cases also cast steel. The guns are muzzle-loaders, for the French experiments with breech-loaders were not satisfactory. Each gun has six trough-shaped grooves, 5 millimetres deep and 16 millimetres broad; the angle of twist seems to be only slight, but no details are known on this point. The windage of the projectile amounts to about 1/2 to 1 millimetre, and on the ailettes or studs that engage the grooves somewhat less than 1 millimetre. The projectile is cylindrical-ogival and hollow, weighs filled about 12 pounds and has six studs, one for each groove, three placed near the point and three near the base of the projectile. They are very short—about 15 millimetres long. The fuze-hole runs downwards from the point and is closed, in projectiles filled with powder, by a fuze-tube or a fuze cone with a percussion cap, and when the projectile is not to explode, by an iron screw. In the latter case it is filled with a mixture of sawdust and sand so that it has the same weight as the powder-filled projectile. The length of the gun’s barrel is 1,385 millimetres or sixteen times the calibre; the weight of the hard-bronze gun is only 237 kilogrammes (518 English pounds). To correct the deviation of the projectile from the line of sight (lateral deviation) in the direction of the twist—a deviation inherent in all projectiles fired from rifled barrels—the right trunnion carries a so-called horizontal tangent scale. It is reported that the gun, like the carriage, is of very tasteful workmanship, and, on account of its small size and solid finish, resembles a model rather than a real implement of war.

Armed with this gun, the French artillery entered the Italian campaign, where it astonished the Austrians, it is true, by its great range, but certainly not by its accuracy of fire. Very often, even as a rule, the guns fired beyond the target and were thus more dangerous to the reserve than to the foremost lines—in other words, where they carried farther than ordinary guns, they hit people at whom they were not aimed at all. That is certainly a very dubious advantage, because the objects at which the cannon were aimed were in nine cases out of ten not hit. In contrast, the Austrian artillery made a very creditable impression when it faced the French with its matériel, as cumbersome as any in Europe; it advanced to within short range (500 or 900 yards) of this formidable opponent and unlimbered under its heaviest fire. There is no doubt that the French guns, greatly superior as they are to the old smooth-bored cannon, by no means fulfilled what had been expected of them. Their extreme range was 4,000 metres (4,400 yards), and it was undoubtedly only a shameless Bonapartist exaggeration when it was said that they easily hit a single horseman at 3,300 yards’ distance.

The reasons for this unsatisfactory performance in actual war are very simple. The construction of these guns is extremely imperfect, and if the French persist in it, their artillery will in two or three years have the worst matériel in all Europe. The first principle for rifled arms is that they must have no windage, otherwise the projectile, striking loosely back and forth in the barrel and the grooves, will not rotate about its own longitudinal axis, but will move during flight in a spiral about an imaginary line, the direction of which is determined by the chance position of the projectile on leaving the muzzle, the diameter of the spiral increasing with the distance. Now the French guns have a considerable windage and cannot dispense with it so long as the ignition of the column-fuze of the hollow projectile depends on the explosion of the propelling charge. This, then, is a circumstance which explains the lack of accuracy. A second is the unevenness of the propelling force produced during the explosion of the charge by the more or less considerable escape of gas through the windage. A third is the greater elevation which is required, with the same charge, on account of this windage. It is obvious that where no gas can escape between the projectile and the walls of the barrel, the same charge has a greater propelling force than where part of the gas escapes. Now it seems that the French artillery requires not only a very heavy charge for rifled guns (one-fifth of the weight of the projectile), but also a rather considerable elevation. The greater range which rifled barrels attain in comparison with smooth-bored ones even with a smaller charge is mainly obtained because there is no windage and consequently the guarantee that the whole explosive force of the charge is used to propel the projectile. With the French, a part of the propelling force is lost through the windage, and they must compensate for this, up to a certain degree, by a larger charge and, beyond that, by a greater elevation of the piece. But at all distances nothing is so detrimental to accuracy as a great elevation. As long as the trajectory of the projectile, at its highest point, does not much exceed the height of the target, an error in estimating the distance is of but little consequence; but at a great range the projectile has a very high trajectory and comes down at an angle which is on average twice as great as at the beginning of its flight (this applies, of course, only to elevations up to about 15 degrees). The greater the elevation, then, the more the line in which the projectile strikes the ground approaches the vertical, and an error of no more than 10 or 20 yards in calculating the distance may make it impossible to hit at all. At ranges of over 400 or 500 yards, such errors are unavoidable, and the result is the astonishing difference between the excellent shooting on the practice ground, with measured distances, and the miserable practice on the battlefield, where the distances are unknown, the targets move, and the time for reflection is very short. Hence the chance of hitting with the new rifled small-arms on the battlefield beyond 300 yards is also very slight, while below 300 yards, owing to the flat trajectory of the bullet, it is very great. Consequently, the bayonet charge is the most effective means of ejecting an enemy from his positions as soon as the attacking body of troops has come up to this distance. If we assume that one army has rifled small-arms which do not achieve a higher trajectory at 400 yards than those of their opponents at 300 yards, then the former will have the advantage of being able to open an effective fire from a distance 100 yards greater, and as only three or four minutes are needed to traverse 400 yards during an attack, this advantage is no small one at the decisive moment of a battle. It is similar with guns. Sir Howard Douglas declared ten years ago that gun to be by far the best which has the greatest range with the least elevation. With rifled guns the importance of this property is still greater, as the possibility of error in estimating the distance increases with the greater range, and ricochet fire can only be relied upon with round projectiles. That is a disadvantage of rifled guns; in order to hit at all, they must hit at the first graze, whereas round shot, when they fall short, ricochet and continue their flight in much the same direction. With rifled guns, therefore, a flat trajectory is of the very greatest importance, as every additional degree of elevation increasingly diminishes the possibility of hitting at the first graze. For this reason the strongly curved trajectory of the French guns is one of their most serious defects.

However, the shortcomings of these guns are increased by a defect surpassing all others, one which suffices to characterise the whole system. They are manufactured by means of machines and in the manner which formerly served for the fabrication of the old smooth-bored guns. With the very great windage of these old guns and the differing weights and calibres of the projectiles, mathematical precision in production was of only secondary importance. The manufacture of fire-arms was, until a few years ago, the most backward branch of modern industry. There was far too much hand labour and far too few machines. For the old smooth-bored weapons this might have answered, but when weapons were to be produced from which great precision at great distances was expected, this method became useless. To have the certainty that the performances of the small-arms at 600, 800 and 1,000 yards, as well as those of the cannon at 2,000, 4,000 and 6,000 yards, are completely equal, it became necessary to have every smallest operation done by the most perfect mechanical machines, so that each weapon becomes the mathematically exact counterpart of another. Deviations from mathematical exactness, which were insignificant under the old system, now led to defects that rendered the whole weapon worthless. The French have scarcely improved their old machinery to a noticeable extent, and from this result the deviations in their artillery fire. How, then, can it be attained that guns give the same range at the same elevation and with complete equality of all other circumstances, if they do not correspond with one another down to the minutest detail? But inaccuracies in manufacture, which at 800 yards’ range yield differences of one yard, will at 4,000 yards’ range lead to differences of 100 yards. How, then, can reliability be expected from such guns at great ranges?

To recapitulate: The French rifled guns are bad because they require windage in the barrel, need a comparatively great elevation, and their execution in no way corresponds to the requirements of rifled, long-range guns. They must soon be superseded by other patterns, or the French artillery will be the worst in Europe. We have intentionally examined these guns somewhat in detail, because it offered an opportunity to explain the most important principles of rifled cannon. In a concluding article we shall consider the two proposed systems which are now contending for supremacy in England, models which both, with perfect workmanship, are based on the breech-loading system and have no windage—the Armstrong and the Whitworth system.

["New-York Daily Tribune" No. 5938, 5 May 1860]

III

We now come to the description of the two kinds of rifled breech-loaders which are at present contending for supremacy in England and which, both invented by civilians, certainly surpass in effectiveness anything that has ever been produced by professional artillerists—the Armstrong and the Whitworth gun.

William Armstrong’s gun had the advantage of priority and the praise of both the press and the public of all England. It is unquestionably a highly effective war machine and far superior to the French rifled cannon; but whether it will surpass the Whitworth gun may be greatly doubted.

Sir William Armstrong constructs his gun by spirally laying two layers of wrought-iron bars around a tube of cast steel, the upper layer in the opposite direction to the lower, in the same way that gun barrels are manufactured from layers of wire. This method yields a very strong and durable, though also very costly, material. The barrel wall has numerous narrow, closely spaced grooves, which give the projectile one complete turn within the entire barrel. The cylindro-ogival elongated projectile is made of cast iron, but is surrounded by a coat of lead, which gives the projectile a somewhat larger diameter than the calibre of the barrel. This projectile, together with the cartridge, is introduced into the chamber by means of the movable breech, the chamber being large enough for this purpose. The explosion drives the projectile into the narrow barrel, where the soft lead is pressed into the grooves and all windage is thus eliminated; at the same time the projectile receives the spiral motion about its longitudinal axis determined by the twist angle of the grooves. This method of pressing the projectile into the grooves, and the coat of soft material required for it, are the characteristic features of the Armstrong system, and if the reader refers back to the principles of rifled guns which we developed in our preceding articles, he will agree with us that Armstrong is, in principle, decidedly on the right track. Since the projectile is larger in diameter than the calibre, the gun is inevitably a breech-loader, which also seems to us a necessary feature of all rifled guns. The breech-loading mechanism itself, however, has absolutely nothing to do with the principle of a particular system of rifling, but can be transferred from one system to another; we therefore leave it entirely out of our considerations.

The range and the precision achieved with this new gun are simply astonishing. The projectile was thrown about 8,500 yards or almost 5 miles, and the certainty with which the target was hit at 2,000 or 3,000 yards far exceeded anything that the old smooth-bore cannon could exhibit at one third of these distances. Nevertheless, despite all the shouting of the English press, the scientifically interesting

details of all these experiments were kept strictly secret. It was never announced with what elevation and with what charge these ranges were attained. The weight of the projectile and that of the gun itself, the exact lateral and longitudinal deviations, etc. were never published in detail. Now, at last, since the Whitworth gun has appeared, we learn at least something about a series of trials. The Secretary of War, Sidney Herbert, reported to Parliament that an 8-hundredweight twelve-pounder, with a powder charge of 1 pound 8 ounces, at 7 degrees elevation, attained a range of 2,460 yards, with an extreme lateral deviation of 3 and an extreme longitudinal deviation of 65 yards. At 8 degrees elevation the range was 2,797 yards, at 9 degrees over 3,000 yards, the deviations remaining almost the same. An elevation of 7 to 9 degrees is, however, something unknown in the practice of smooth-bore field guns. The official tables, for example, do not go beyond 4 degrees elevation, at which the twelve- and nine-pounders achieve a range of 1,400 yards. Any greater elevation would be worthless in field guns, since it would give too high a trajectory and thereby immensely reduce accuracy. However, we are acquainted with some experiments with heavy smooth-bore naval guns at greater elevations (mentioned in Sir Howard Douglas’s “Naval Gunnery”). The long English 32-pounder yielded at Deal in 1839, at an elevation of 7 degrees, ranges from 2,231 to 2,318 yards, at 9 degrees from 2,498 to 2,682 yards. The French 36-pounder of 1846 and 1847 yielded at 7 degrees a range of 2,270, at 9 degrees a range of 2,636 yards. This shows that, at the same elevation, the ranges of rifled guns are not very much greater than those of smooth-bore guns.

The Whitworth gun is opposed to the Armstrong gun in almost every respect. Its bore is not circular, but hexagonal; the twist angle of its rifling is nearly double that of the Armstrong gun; the projectile consists of very hard material without any lead coat; that it is a breech-loader is, with Whitworth, not a question of necessity, but merely a question of convenience and fashion. This gun is manufactured of a recently patented material called “homogeneous iron,” which is distinguished by great strength, elasticity, and toughness; the projectile fits mathematically exactly into the barrel and can therefore only be introduced when it is lubricated. This is effected by a mixture of wax and tallow placed between the charge and the projectile, which at the same time helps to reduce any

windage still remaining. The material of the gun is so resistant that it can easily withstand 3,000 rounds without the barrel wall suffering as a result.

The Whitworth gun was presented to the public last February, when a series of experiments with it was carried out at Southport, on the Lancashire coast. There were three cannon – a three-pounder, a twelve-pounder, and an eighty-pounder. From the detailed reports we select the twelve-pounder for illustration. This cannon was 7 feet 9 inches long and weighed 8 hundredweight. The ordinary twelve-pounder for round shot is 6 feet 6 inches long and weighs 18 hundredweight. With the Whitworth cannon the following ranges were attained: at 2 degrees elevation (at which the old twelve-pounder reached 1,000 yards) with a charge of 1
1
/
2
pound the range varied from 1,208 to 1,281 yards. At 5 degrees (at which the old 32-pounder reached 1,940 yards) it came to a range of from 2,298 to 2,342 yards. At 10 degrees (range of the old 32-pounder 2,800 yards) it gave an average of 4,000 yards. For greater elevations a three-pounder cannon with an 8-ounce charge was used; at 20 degrees it had a range of from 6,300 to 6,800, at 33 and 35 degrees from 9,400 to 9,700 yards. The old 56-pounder smooth-bore attains at 20 degrees a range of 4,381 yards, at 32 degrees one of 5,680 yards. The precision attained by the Whitworth cannon was very satisfactory and, with respect to lateral deviation, at least as good as that of the Armstrong cannon; with regard to longitudinal deviations the experiments do not permit of satisfactory conclusions.