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'Miscellaneous Papers on Mechanical Subjects | Guns and Steel' by Sir Joseph Whitworth, Bart., was published in London by Longmans, Green Reader, & Dyer in 1873. The text reproduced here is from Chapter II and concerns Whitworth's involvement in rifle design. The remainder of the work concerns artillery and Whitworth's 'fluid-compressed steel.'

Preface

It is probable that few are aware of the manner in which I approached the subject of rifling guns, or know that the Whitworth rifle was produced as the result of many months of experimental research in the rifle gallery, five hundred yards long, erected in my grounds at Manchester. I cannot mention this fact without saying how much personal interest the then Commander-in-Chief, Lord Hardinge, took in the experiments, every stage of which he communicated to the Prince Consort. At that time I demonstrated every conclusion by the most carefully conducted trials, and I proved that the Enfield service rifle of that day was wrong in every particular. The diameter of the bullet was too large for the size of the gun, the bullet itself was too short, and the twist of rifling was not one-third of what it should have been. Accordingly, in the year 1857, the public trials of my rifle against the Enfield rifle, made by the direction of Lord Panmure, established the superiority of my weapon, as well as the soundness of the conclusions at which I had arrived.

In 1859 a Committee of officers reported that the bore of my muzzle-loading rifle was too small for use as a military weapon.

In 1869 another Committee recommended that the bore of the service breech-loading rifle should be exactly that rejected ten years previously.


IN the year 1854, when Lord Hardinge was endeavouring to obtain the best possible rifle with which to arm the British troops, he requested me to aid him by investigating the mechanical principles applicable in the construction of an efficient weapon. I willingly agreed to do so, subject, however, to the condition that I should have a suitable gallery, protected from changes in the wind and from fluctuations in the atmosphere, wherein to carry on the experiments which were necessary for enabling me to arrive at any sound conclusion.

It was absolutely essential to track the path of a rifle bullet throughout its entire course, to determine whether its point preserved a true forward direction, and to record its trajectory. This could be done most readily in a closed gallery provided with screens of very light tissue paper.

Accordingly a gallery, 500 yards in length, was erected in my grounds at Rusholme, in the year 1855. Its height was 20 feet and width 16 feet; it was slated, and had openings on the south side only for the admission of light and for getting rid of the smoke.

The first result of the work done in this gallery was the construction of my small-bore rifle.


First Comparative Trials Of The Whitworth And Enfield Rifles

In the year 1855 I commenced a series of experiments in the new rifle gallery, and was at that time requested to adhere to the service charge of powder, viz., 70 grains, as well as to the service weight of bullet, viz., 530 grains, but I was unrestricted in every other particular.

The barrel of the Enfield rifle, as then used in the service, was 39 inches in length, its bore being .577 of an inch in diameter. The rifling was effected by three spiral grooves, making 1 turn in 78 inches, and the bullet rotated half a turn during its passage along the barrel. The length of the bullet was 1.81 diameters of the bore.

The bullet was cylindro-conoidal; it was wrapped in paper, and was made of such a size as to pass easily down the barrel, and had a conical wood plug in its hollow base. At the instant of firing, the explosive force of the powder caused the bullet to become expanded or upset, and thus moulded it to fit the grooves in the bore. It was essential that the lead should be very pure and soft in order to allow of its being properly expanded into the grooves.

The bullet is shown in the diagram.

The cross section of the barrel is given at D, the circular portions, which do no work in rotating the bullet, are called lands, and the grooves run in a screw thread of uniform pitch between the lands.

The barrel of the Whitworth rifle is 39 inches in length, the interior is hexagonal in section, and, instead of consisting partly of non-effective lands and partly of grooves, has rifling surfaces which are wholly effective. The rifling turn is much quicker than that of the Enfield rifle, being 1 turn in 20 inches, and the angular corners of the hexagon are rounded in the manner shown. The maximum diameter of the bore is .490 of an inch, and the minimum diameter is .451 of an inch.

The bullet may be either hexagonal or cylindrical; in the latter case, it will expand and be driven into the recesses of the hexagon, and will adapt itself to the curves of the spiral rifling; in the former case the inclined sides of the hexagon offer no direct resistance to this expansion, which is easily effected. The length of the bullet is 3 diameters of the bore.

With all expanding bullets, a quick burning powder must be employed. The expansion depends on the sudden action of the powder upon a bullet possessing inertia, it therefore fails with a slow burning powder.

If there be a mechanical fit between the bullet and the bore of a muzzle-loading rifle, this expansion is no longer necessary, and the bullet may then be made of alloys of tin and lead of any degree of hardness, or a hardened steel bullet may be used. It is perfectly easy to form a mechanically-fitting bullet adapted to the hexagonal rifling, on account of the simplicity of the form, but quite impracticable to obtain an accurate fit between the bullet and the bore of the rifle where any system of grooves is adopted.

The expansion principle may be combined with an easy mechanical fit, so that a projectile made of metal harder than lead, such as an alloy of lead and tin, may be used, and the bullet will then expand sufficiently to fill the bore, giving a penetration more than double that of lead.

In my earlier experiments I tried the effect of lengthening the bullet of the Enfield rifle, and I showed, by means of a piece of tissue paper placed three yards from the gun, that an increase of only a quarter of an inch in length caused the bullet to strike obliquely. This fact was clearly ascertained by the mark left upon the paper. I then made a barrel of the same bore with a twist of 1 turn in 30 inches, instead of 1 turn in 78 inches, and I kept the weight of the lengthened bullet at 530 grains by making a portion of the interior hollow. The result was that with the same charge the bullet hit the target at the same height.

Having thus proved that there was no loss of range on account of the increased rotation of the bullet, and that the trajectory was as good as before, I made another barrel, reducing the minimum diameter to .5 inch, and lengthening the projectile, and finally I reduced the bore to .45 inch.

In order to satisfy myself as to the effect of increased twist in the rifling I tried barrels with 1 turn in 20 inches, 1 turn in 10 inches, 1 turn in 5 inches and lastly with 1 turn in 1 inch. I fired from these barrels mechanically fitting bullets of lead and tin, and with the barrel rifled to 1 turn in 1 inch (using 35 grains of powder) I penetrated through 7 inches of elm-tree planks.

In this way I exhausted the subject, and arrived at the result that the best twist for a rifled musket bullet would be 1 turn in 20 inches, the minimum diameter of the barrel being .45 inches.

This construction gave the best shooting with the charge of powder and weight of bullet to which I was limited.

If the ordinary strength of a man was greater than it is, the Enfield bore would be right but it would be necessary to increase the length of bullet and the twist of rifling, the rifle itself being also made heavier in proportion.

I experienced great opposition to the change of rifle turn from 1 turn in 78 inches to 1 turn in 20 inches, or I should have made the twist somewhat more rapid in order to fire a steel bullet when necessary for penetration. It should be understood that the amount of rotation must be increased when the specific gravity of the bullet is made less, otherwise the projectile will fall over in its flight, - that is to say, an iron projectile requires more rotation than one made of lead.

The same principles apply in determining the rotation for the heaviest guns. A long projectile turns over unless it has sufficient rotation, and the twist for field guns should not be less than 1 turn in 15 diameters. The gun will then fire projectiles 6 diameters in length.

I have always contended that the primary element of success in long range shooting, is length of bullet, and generally that great range, with a low trajectory, accuracy and penetration are obtained by employing a long bullet, high rotation, and a large powder charge.

The superiority of the Whitworth, as compared with the Enfield rifle, was first proved in a series of trials made at Hythe, in the year 1857, under the direction of Lord Panmure, then Minister of War.

These trials led to no satisfactory conclusion, and after a lapse of eighteen months a Committee of Officers reported to the Government in 1859 that the bore of my rifle was to small for use as a military weapon.

Compare with this the report of another Committee of Officers made in 1862, "that the makers of every small-bore rifle, having any pretensions to special accuracy, have copied to the letter the three main elements of success adopted by Mr. Whitworth, viz., diameter of bore, degree of spiral, and large proportion of rifling surface."

In 1869 a Special Committee reported to the War Office that the calibre of a breech-loading rifle, should be .45 inches, as appearing to be the most suitable for a military arm. This conclusion is directly contrary to that arrived at in 1859, but is the exact bore which I recommended in 1857.

The mechanical question is the same whether we deal with a rifled musket or the heaviest gun. I have from the commencement advocated one uniform system, the value of which I have established by direct experiment.

As regards heavy artillery, it will probably require some long interval before the professional advisers will be enabled to see that sound ductile steel is the best material for a gun, that the bore for a given weight of gun should be made smaller than that used in the service, that the projectile should be lengthened, that its rotation should be increased, and that the stud system should be abolished.

In this direction they have made one step. They have taken the weight I proposed for a gun of 12 inches bore, and have increased the weight of the service 12 inch gun from 25 to 35 tons. In all other respects the Woolwich system is in direct opposition to my own. Following past precedent it must be expected that when the truths I have endeavoured to press upon official attention are fully understood, and action is taken upon them, my part in first developing them will probably be forgotten.


Rifle Trials At Hythe In 1857

The peculiar features or the Whitworth rifle may be summed up as follows:-

1.- The bore is much smaller than that of the Enfield rifle.

Whitworth - Maximum diameter .49 inch, - Minimum diameter .45 inch
Enfield - Maximum diameter .61 inch, - Minimum diameter .577 inch

2.- The length of the bullet is increased.

Whitworth - length 3 diameters
Enfield - length 1.81 diameters

3.- The twist of the rifling is increased.

Whitworth - 1 turn in 20 inches
Enfield - 1 turn in 78 inches

4.- The form of the Whitworth bore is polygonal, being a hexagon with the edges rounded. The form of the Enfield bore is cylindrical, with grooves and lands.

The Government were desirous of testing the merits of my new arm, and of comparing it with the Enfield rifle, and a series of trials were made by the direction of Lord Panmure. The subjoined account of these trials, is extracted from the "Times," of April 23rd, 1857:-

For the last few days a very interesting and important series of experiments has been in progress at the Government School of Musketry, Hythe, in order to test the comparative merits of the Whitworth and Enfield rifles. The trial, which was of a most searching and impartial character, was conducted by Colonel Hay, the able head of the school, and has terminated in establishing beyond all doubt the great and decided superiority of Mr. Whitworth's invention. The Enfield rifle, which was considered so much better than any other, has been completely beaten. In accuracy of fire, in penetration, and in range its rival excels it to a degree which hardly leaves room for comparison.

The following table gives the best results that have been obtained from 10 shots of each arm respectively in the course of the experiments, which were brought to a close yesterday, in the presence of Lord Panmure, and of a number of military and scientific spectators:-

Rifle Range
Yard
Elevation
Degrees
Figure of Merit*
Feet
Whitworth
Enfield
500
500
1.1
1.32
0.37
2.24
Whitworth
Enfield
800
800
2.22
2.45
1.0
4.11
Whitworth
Enfield
1100
1100
3.45
4.12
2.41
8.04
Whitworth
Enfield
1400
1400
5.0
6.20 to 7.0
4.62
no hits
Whitworth
Enfield
1800
1800
6.40
--
11.62
--

* The figure of merit is the average divergence of the number of shots fired

It would appear from these figures that at 500 yards, in 10 shots, the Manchester rifle has a superior accuracy of 1.87 of a foot; at 800 yards 3.11; at 1,100 yards 5.63; and that at 1,400 yards and upward, the Enfield weapon ceases to afford any data for comparison. In penetration the results have been equally decisive; the Whitworth projectile with the regulation charge of powder going through 33 half-inch planks of elm, and being brought up by a solid bulk beyond, while the Enfield ball could not get past the 13th plank. 

All these were made by firing from a beautifully constructed machine rest, which placed both weapons on a footing of perfect equality, as to the other condition under which they were tested.

By referring to the table of experiments it will be seen that the target made by the former weapon at 1,100 yards so nearly as good as that made by the latter at 500 yards. These are great results to have achieved, and amply justify the forethought of the late Lord Hardinge in securing the services of so eminent a mechanic as Mr. Whitworth for the improvement of the rifle. Until he took the subject in hand the proper principles for guidance in the construction of the weapon had not been accurately determined.

General Hay informed me that the best figure of merit obtained by any rifle at a range of 500 yards, before the year 1857, was 24 inches, and here the new Whitworth rifle had a figure of merit of 12 inches at 800 yards, and of 4.62 feet at 1,400 yards. The figures of its competitor, the Enfield rifle, at the same ranges were 4.11 feet and "no hits," that is to say, the Enfield bullet could not touch a target, 14 feet square, at 1,400 yards range.

The accuracy of the Whitworth rifle may be estimated from the following facts, a figure of merit of 10.5 inches has been obtained at a range of 1,000 yards, 20 shots being fired. At a range of 500 yards it is a common thing to obtain a mean deviation of 3 to 5 inches, from my mechanical rest in the gallery, with 20 shots.


Trials Of The Whitworth And Enfield Rifles, Made At Woolwich In The Year 1857

After the contest at Hythe, a series of experiments were conducted by a Committee appointed by the Minister of War, and the enquiries were especially directed to these points:-

(1) Precision, (2) penetration, (3) range.

The trials were made in July and August, 1857, and the best results obtained from the Whitworth and Enfield rifles were officially reported to be the following:-

Rifle Range
Yard
Figure of Merit

Whitworth
Enfield
500
500
10.194
18.240
Whitworth
Enfield
800
800
18.264
45.750
Whitworth
Enfield
1400
1400
74.844
110.451
Whitworth
Enfield
1700
1700
129.762
beyond range
Whitworth
Enfield
2000
2000
129.565
beyond range

In the experiment on penetration, a Whitworth bullet made of a hard alloy passed through 34 half-inch elm boards, while a tubular bullet passed through 34 of the same boards, cutting out clean cores in its passage. The range was 307 yards.

I have not any record of the penetration of the Enfield bullet, except that given in the Hythe trials, where it passed through 12 half-inch elm planks, and was stopped by the 13th plank.


A Rifle Fired By The Queen

The first prize meeting of the National Rifle Association was held at Wimbledon on the 2nd July, 1860. Her Majesty, the Queen, graciously signified her intention of inaugurating it in person, and also of firing the first rifle shot.

Accordingly a Whitworth rifle was mounted on the mechanical rest, which is dependent on the use of my true planes for its geometrical exactness. The drawing shows the rest supported on a tripod stand, and weighted to ensure steadiness; the rifle is placed on a light steel slide, having true plane surfaces sliding on other true planes, which construction ensures that the recoil of the piece shall take place in one definite unchangeable line. Nothing can disturb the accuracy of the aim at the instant of firing.

A spring balance fixed on a smaller tripod, also weighted, receives the recoil by means of a projecting arm, and measures, its amount.

The target having been fixed at a distance of 400 yards, a silken cord attached to the trigger was handed to Her Majesty by me, and the rifle was discharged by a slight pull on the cord.

The adjustment was so accurate that the bullet struck the target within 1.25 inches from the centre, or point of intersection of the two cross lines, as shown by the diagram copied from a photograph:-


Report By The Ordnance Select Committee

On the 26th of November, 1862, the Ordnance Select Committee published the following results of a series of trials made with the Whitworth and Enfield rifles.

The dimensions and constructions of the two rifles are stated below, the mean angle of elevation for a given range is tabulated, and also the mean radial deviation, or figure of merit. The experiments were instituted by the Secretary of State for War in the year 1861.

ENFIELD:- 

Diameter of bore 0.577in.
Pitch of rifling, 1 turn in 78ins.
No. of grooves 3 

WHITWORTH:-

Diameter across angles, 0.490in.
Diameter across flats, 0.451in.
Pitch of rifling, 1 turn in 20ins.
No. of grooves Hexagon.

  ENFIELD WHITWORTH
Range
Yards
Mean Radial
Deviation
Mean
Angle
Mean Radial
Deviation
Mean
Angle
  inches   inches  
300 12.69 0° 44' 8" 3.86 0° 56' 49"
500 19.80 1° 45' 13" 7.29 1° 23' 37"
800 41.61 2° 46' 6" 15.67 2° 17' 6"
1,000 95.01 4° 3' 33" 23.13 3° 5' 36"
1,200 133.53 5° 9' 48" 46.92 4° 3' 6"

Henry & Metford Rifles 

I here confine myself to pointing out the manner in which my system has been followed in the construction of the Henry and Metford rifles. The drawing shows in section the bore of each gun, as well as the respective bullets.

The Henry rifle has a polygonal bore with seven instead of six sides.

The diameter of a circle touching each flat side of the polygon is .45 of an inch; the maximum diameter of the grooving is .457 of an inch.

The bullet is 2.93 diameters in length.

The twist of the rifling is 1 turn in 22 inches.

When the bullet moulds itself to the form of the rifling, each angular point is cut away by the seven projecting sharp edges which protrude in the barrel at the junction of the sides of the polygon.

This alteration in the rifling of my barrel was no doubt done in order to meet the requirements of a cylindrical hardened lead bullet, which cannot be much upset by the powder. It may be very well for match shooting when in good order. The difference between the maximum and minimum diameters is small, and the amount of upsetting required by the bullet is proportionately less but the use of a steel bullet is rendered impracticable, and the rifling is unsuited for the great wear and tear of a military weapon.

Regarded as a military arm, the additions to my barrel above referred to have nullified its efficiency.

I was the first to use a hardened bullet, but I made it the shape of the barrel, and obtained a mechanical fit, which enabled me to use a steel or any other hardened bullet.

The alteration of the twist from 1 turn in 20 inches to 1 turn in 22 inches, must have been made purely for the sake of alteration. I had found it requisite to go from 1 turn in 78 inches of the Enfield to 1 turn in 20 inches. If the steel bullet is to be considered a matter of importance, I should prefer I turn in 17 inches, because steel requires a higher rotation than lead on account of its less specific gravity.

The Metford rifle has a bore of a cylindrical character. It is made up of a series of cylindrical portions concentric with the axis of the bore, and alternating in size. This provides a series of grooves, five in number, and cylindrical in section, with sharp sloping edges.

The maximum diameter is .47 of an inch, the minimum diameter being .462 of an inch.

The bullet is 3.02 diameters in length.

The barrel is rifled with an increasing twist, commencing at the breech end with 1 turn in 48 inches, and terminating at the muzzle with 1 turn in 16 inches.

It will be remembered that in the Whitworth rifle the bore is hexagonal, the mean diameter is .47 of an inch, the bullet is 3 diameters in length, and the twist of the rifling is 1 turn in 20 inches.


Hexagonal Rifling

I have stated that the form of the bore of the Whitworth rifle is polygonal, being a hexagon with rounded edges; it is therefore a combination of a straight line and a circle, and its surfaces are those most easily produced in the workshop.

There is a geometrical simplicity pertaining to the polygonal form which is unattainable by any other form.

The amount of bearing surface for giving rotation, and which also conduces to the centreing of the shot, depends upon the difference between the maximum and minimum diameters of the bore, this difference, in fact, represents the hold which the barrel has upon the projectile. In any grooved system of rifling you pass more rapidly from the maximum to the minimum diameter, and the extent of bearing surface is diminished accordingly, whereas in the hexagonal system, there is a long inclined bearing surface, the section of which is a straight line starting from the minimum diameter and running into a circle at the end of the maximum diameter.

A polygonal rifled projectile is applicable to the largest cannon as well as to small arms, and I have adopted the hexagonal form, because it gives me the best working difference between the maximum and minimum diameters.

It will be observed that the hexagonal form of the projectile is analogous to that of the hexagonal nut universally used.

It may be said that this record of my experiments, showing how the modern rifle has become what it is in range, in penetration, and in accuracy, has ceased to be of interest or importance since the new element of rapid firing has been brought to bear with such important results by the introduction of breech loading. I would state in reply that breech loading and rapid fire give increased importance and value to range, penetration, and accuracy, as the primary and essential qualities of the rifle. However necessary these qualities may have been for the muzzle-loader, they are still more requisite with an arm which must otherwise waste its ammunition. Rapid firing must rest on the very best system of rifling, as its only safe basis.