In Fig. 50, A represents the ram of an hydraulic press, and B a circular punch, the lower angles of which are slightly rounded; C is a circular ring, or die, having a trumpet-shaped mouth, shown in section, and resting on the hollow bed D, of the hydraulic press. A circular recess of 27 in. in diameter was made on the upper side of the die to receive the plate of steel to be operated on; E, Fig. 50, shows the cold plate of steel placed in the die ready for bulging. The descent of the ram forced the plate into a dished form, shown at E in Fig. 51. The further descent of the ram, as shown in Fig. 52, drove the plate nearly through the die: it, however, still had its mouth slightly splayed. Another movement of the ram pushed the plate entirely through the die, and made it into a plain parallel cylinder, with a slightly-rounded bottom, as represented at Fig. 55. In spite of this marvellous transformation, in form and dimensions, the metal remained at all parts wholly uninjured, as was incontestably proved by the fact that the cylinder became a beautiful sonorous bell, in which the critical musical ear could not detect any fault in tone, due to crack or injury of any kind.
Now let us for one moment consider what changes the solid cold steel
underwent, as it flowed like a piece of plastic clay, and suffered so
great a change in the position of all its constituent particles. In
Fig. 53 we have the original disc seen on edge; it was 3/4 in. in
thickness, 27 in. in diameter, and 84 3/4 in. in circumference; both
its sides were originally of the same area. When made into a cylinder
or cup it measured on the outside 34 1/2 in. in circumference, and on
the inside 29 in. only; the metal which originally formed its outer
circumference had been reduced to 34 1/2 in. Such a change of form and
flow of cold steel from one part of the mass to another, required
enormous force, and yet so great was the toughness and resilience of
this mild steel that the changes of form and dimension were possible
without producing a symptom of rupture. I fearlessly challenge any
person of ordinary intelligence to study, however slightly, these
diagrams, and then to cast his eye on the accompanying illustration,
Fig. 56, Plate XX., which is a reproduction of this steel cup, without
coming to the conclusion that in these early days of the Bessemer
process we could, and did, produce a metal pre-eminently adapted to the
construction of ordnance: a metal that could be manufactured from
Swedish charcoal pig-iron in homogeneous, unwelded masses of from 5 to
20 tons in weight, at less than one-half the price paid for Lowmoor
iron bars, from which the Armstrong gun coils were made. I cannot tell
the precise date of the actual production of the cup illustrated, but I
know it was many months before the great Exhibition of 1862. I can
trace it back to that period by evidence that cannot be disputed. The
Engineer newspaper of the first week in May, 1862, describing my
exhibit of Bessemer steel, says:
There are also some extraordinary examples of the toughness of Bessemer
steel made from British coke-made pig-iron, among which may be
enumerated two deep vessels of one foot in diameter, with flattened
bottoms and vertical sides; at the top edge, one of them is 5/8 in. and
the other 7/8 in. in thickness. These are formed up in a press from
flat circular discs of steel.
They can now be drawn into long tubes, either of their present
diameter, or they may be reduced to locomotive boiler tubes of 2 in. in
diameter; there is also shown an attempt to raise a piece of the best
Staffordshire iron plate by the same tools; this only went about as
deep in proportion as an ordinary soup plate before it fractured all
around the punch, and almost fell into two pieces. It may be remembered
that Mr. Parkes, who invented this beautiful system of making unwelded
tubes, has been obliged to use the very highest quality of copper for
that purpose; the ordinary copper of commerce generally cracks, but the
Bessemer steel, as seen by these examples, stands this fearful ordeal
with perfect safety.
On the closing of the Exhibition of 1862, I presented this cup to Dr.
Percy, who placed it in the gallery of the Geological Museum in Jermyn
Street, whence it was, many years ago, transferred to the South
Kensington Museum. The Curator kindly allowed me to have a photograph
taken of it, and from this photograph the engraving on Plate XX. has
been made.
Since writing the above, I have called to memory an earlier date on
which one of these deep cups was exhibited. I refer to the occasion of
Sir William Armstrong's visit to Sheffield, as President of the
Institution of Mechanical Engineers, which held its summer meeting
there on July 31st, 1861; in proof of this I refer to the copy of my
Paper as printed and issued by that Institution. In the Proceedings of
the Institution the Secretary interpolated, between the reprint of my
Paper and the report of the discussion thereon, the announcement which
is here reproduced.
Mr. Bessemer exhibited an 18-pounder gun made of the Bessemer steel
cast in a single ingot of the required size and subsequently hammered,
with a variety of specimens of the metal, broken to show the quality of
the fracture; also some piston rods, a boiler plate flanged for a
locomotive fire-box, and a plate bulged in a die without cracking or
tearing; a plate of thin metal punched with a number of small holes
very close together, and a tube of the metal which had been crushed
flat without the surface of the metal cracking. He showed also one of
the fireclay tuyères used for blowing the melted metal in the
converting vessel, and specimens of the ganister used for lining the
vessel and ladle, both new and after use.
The "variety of specimens of the metal broken to show the quality of
the fracture" should have been described as "specimens crushed to show
the toughness of the steel." "A plate bulged in a die" is the deep cup
made from a flat piece of boiler plate 27 in. diameter, and already
mentioned as being illustrated in Fig. 56, Plate XX. The tube
of metal crushed flat without cracking (see C, Fig. 49, Plate XIX.) was
similar to the crushed gun-tubes so many years exhibited in the South
Kensington Museum, and now in the possession of the Iron and Steel
Institute. Figs. 57 to 60, on Plates XXI, XXII., and XXIII., show other
specimens exhibited at the meeting.
It is unnecessary to multiply examples, since those already given
cannot fail to convince any unprejudiced person that in these early
days of the Bessemer process all those manufacturers who understood it,
and took the amount of care which is necessary in all
properly-conducted manufacturing operations, were able to produce steel
of high quality with as great a degree of regularity as is common with
any other modes of production. I, however, cannot refrain from giving
yet another instance of the wonderful tenacity and endurance of this
metal when subjected to the most violent strains.
About the year 1862, a Mr. Thompson, of Bilston, took out a patent for
a novel and ingenious mode of manufacturing Enfield rifle-barrels, and
after many trials he chose Bessemer mild steel as the material most
suitable for this purpose. Our works at Sheffield supplied him with
large quantities of mild steel, in the form of round bars 3 in. in
diameter. These were afterwards sawn into lengths of about 6 in., and
when made red-hot were placed on end under the steam-hammer, which
carried a cylindrical steel punch of 1 in. in diameter, having a
conical end resembling an armour-piercing shot, as shown in Fig. 61.
The hammer A had projecting from it the punch B, beneath which was
placed the steel piece C, shown partly pierced by one or two blows. This piece
was placed over an opening in the anvil block D, and after two or three
more blows it was pierced from end to end, forming a short tube from
which no metal has been removed. This violent treatment did not split
or injure the steel in any way, but was well calculated to show any
defect if the metal operated upon was not absolutely sound. After the
operation of punching, the short tubular piece was rolled between a
pair of rollers having a series of tapering grooves formed on them,
and also an enlarged recess to form the breech part out of the solid,
so that a barrel in one piece without welding was produced. This was
afterwards finished in the usual way. The severe test to which these
mild steel barrels were subjected at the Proof House, Birmingham, is
shown in the annexed tabular statement, which is taken from a Paper
read by me at the Royal United Service Institution on May 2nd, 1864,
and published in the Transactions, from which the Table herewith given
is copied.
TRIAL OF TWO STEEL GUN-BARRELS (ENFIELD PATTERN), AT THE
PROOF-HOUSE, BIRMINGHAM.
With these examples of the extraordinary toughness and tenacity of both
pure Bessemer iron and Bessemer steel, no one, with any knowledge of
the violent strains to which the test pieces were subjected, can doubt
the fact that between the copper-like toughness of the pure Bessemer
iron, and the great tenacity of the more highly carburised steel which
we were at that time supplying to engineers, for making every
description of cutlery and cutting tools, there did exist, and could
easily have been found by trial, the precise quality of steel most
suitable for the construction
of ordnance. It must be borne in mind that it was not until some ten
years later, that is, in the year 1869, that any Siemens-Martin, or
open-hearth steel, was made, and consequently that the only varieties
of cast-steel then available for guns were
crucible cast-steel and Bessemer cast-steel. The fact must also be
recognised that both the difficulty and the cost of producing large
masses of crucible steel increased greatly whenever the metal was
required to be of the very mild quality known as low
carbon steel, which is most difficult to fuse in crucibles, as well as
to retain in fusion during the time occupied in filling a large mould
from hundreds of separate small vessels. Hence the strong temptation
the steel manufacturers had to supply a more carburised, and
consequently a more easily fusible and less tough, steel than was
specified; while the price of this crucible steel was greatly augmented
as the ingot became larger, increasing to over £100 per ton. It is
equally notorious that not one of these disadvantages applied to the
Bessemer metal; it was, in fact, cheaper to produce a single mass of
10 or 20 tons in weight than to make the same weight in a number of
small batches of 3 tons to 5 tons. Nor was there any greater
difficulty
in making the mildest possible quality of steel, because we always
began by making pure soft iron. From the zero point of decarburisation
the hardest qualities of steel could be made, differing by almost
imperceptible gradations, and depending on the number of pounds of
rich carburet of iron added to the pure iron for that purpose.
The material had been proved in all respects suitable for the
manufacture of ordnance, and, as I have already said, Colonel Eardley
Wilmot and I had arranged, under contract, to erect a Bessemer plant in
the old gun foundry at Woolwich, which was amply large enough for that
purpose. This project, had it been carried out, would have rendered
wholly unnecessary the erection of a second arsenal at Elswick, built
under the guarantee of the British Government at a cost of £85,000. It
must also be borne in mind that by my process we had the advantage of
being able to make, if desired, malleable iron guns in a single piece
without a weld or joint, by founding, or by the combined processes of
founding and forging, with or without hoops; so that if malleable iron,
and not steel, had in reality been the best material for the
construction of ordnance, such guns could have been produced at
Woolwich Arsenal, either as complete gun-castings, or as ingots to be
forged, at a cost not exceeding £6 or £7 per ton if made of British
iron, and not exceeding £10 per ton if made of Swedish charcoal
pig-iron; whereas the Lowmoor iron bars used to make the coiled guns
cost over £20 per ton, and were the mere raw material to start with.
Nor did the Bessemer pure malleable iron, if used for guns, admit of
any of the charges that had been made to depreciate the value of steel
for that purpose, namely, that it was very uncertain in quality, and
could not be obtained of the precise degree of carburisation and
toughness required.
Such a charge could not possibly be made in reference to pure iron,
which was wholly decarburised, a condition which it was impossible to
mistake during its manufacture, for the huge white flame issuing from
the converter suddenly drops when all the carbon is burnt out, a
result which occurs with unerring certainty. At all events, if Bessemer
steel could not be depended upon at Woolwich, Swedish charcoal
pig-iron, wholly decarburised, could have been made in masses of 10 to
20 ton, at a cost not exceeding £10 per ton, and
of, at least, 5 tons per square inch greater tensile strength than
Lowmoor bars, as was proved by Colonel Wilmot's experiments at Woolwich
Arsenal; while the cost of the huge unwelded mass would have been less
than half the cost per ton of the bar-iron used to make a welded coil
with its many imperfect junctions.
I should like to say a few words here about the broad distinctive
characters of the two materials, wrought or bar-iron, and cast
homogeneous iron or steel. I need scarcely remind the reader that
bar-iron making begins with the process of puddling, which produces a
ball or mass of iron that, in every case, is mechanically mixed with
fluid scoria, and sometimes with sand and dry oxide or iron scale. From
this crude material, puddle bars are made, and these are cut into
lengths of 2 ft. or 3 ft., and formed into a bundle or pile, which is
brought up to a welding heat in a suitable furnace, and then rolled
into a merchant bar. This process of rolling and piling is repeated
more than twice, and a bar is in this way produced, which to the eye
appears, and is supposed, to have all its separate parts welded or
united so as to form an undivided and indivisible mass. But this is not
so. I have never seen a bar of wrought iron produced by puddling that,
in two or three minutes, by a very simple treatment, I could not
separate more or less perfectly into its component bars, which are in
reality never thoroughly united, although they adhere more or less
soundly. In fact, so imperfect is this adhesion called "welding," that
whenever bar-iron is worked under the hammer, it is necessary to forge
it at such a degree of heat as will continue the welding process; for
by working it much below this temperature, the imperfectly coherent
mass begins at once to separate at all the junctions between the
several bars of which it is composed, and tumbles to pieces.
I will describe an experiment clearly illustrating this fact. Two
pieces of ordinary commercial bar-iron of 1 in. square were heated to a
blood-red heat, and put under a small steam-hammer, where they received
several blows on alternate sides; the result was a complete
disintegration of the mass, as shown in Fig. 62, Plate XXIV. The lower
example was similarly treated on alternate angles, instead of on the
flat sides. It may be supposed that the far-famed Lowmoor and other
Yorkshire irons are exempt from this defect, but this is not so, the
simple fact being that "best-best" iron has been piled more times than
common iron, and the result of working it at a temperature that will
not continue the welding process, only divides it into more numerous
filaments than a bar of common iron. I may mention the fact that, on
one occasion, during a short stay at my works at Sheffield, I had the
honour of a visit from an active partner in one of the great Yorkshire
firms which stand so deservedly high among bar-iron makers. I mentioned
this fact of imperfect welding, and the consequent disintegration of
bar-iron by simply working it at a temperature below welding heat. My
visitor laughed outright at the possibility of such a thing happening
to any bar-iron that his firm had ever turned out. I said: "If you will
wait while one of my people goes to an iron warehouse in the town and
purchases a bar of your iron, I will convince you that I am right."
Well, he patiently waited until the bar was procured, and admitted at
once that the brand stamped on it was his own. A short length was then
cut from it and heated in his presence. It was put under one of the
rapidly-moving tilt hammers at that moment being used in forging our
bar steel at the same low heat. The result was that the Yorkshire iron
bar divided, under this simple treatment, for about a foot of its
length into a mass of fibres forming a veritable birch-broom, to the
utter astonishment of the manufacturer.
At the time when the two bars of 1-in. square iron, shown in Fig. 62,
Plate XXIV., were hammered, a similar bar of Bessemer mild steel was
treated at the same temperature under the same hammer. The
illustration, Fig. 63, Plate XXV., shows how it simply became extended
into a flat undivided surface, without crack or rift in the material.
These examples of forging below a welding heat serve to show the
imperfection inevitable in all puddled or welded iron; while the steel
example also shows the continuity of parts resulting from the Bessemer
steel or homogeneous iron being formed into an ingot while the metal is
in a fluid state, hence producing an undivided and indivisible mass,
however much it may be hammered, hot or cold.
It will be readily understood how deeply interested I was in the
application of my invention to the construction of ordnance, and how
much I felt encouraged by the high appreciation of what I had achieved
by so competent a person as Colonel Eardley Wilmot. Although I saw that
there was an almost endless variety of applications in industry to
which this cheap and superior metal could be advantageously applied, I
nevertheless felt a strong desire to see it used in the manufacture of
guns. Its summary rejection at Woolwich, however, without even a trial,
furnished me with yet another proof of the utter foolishness of relying
on Government, and made me throw up all idea of following that branch
of manufacture as a speciality. With a still lingering desire to put my
material to the test of gun-making, I had looked pretty deeply into the
subject, in order to see what had already been done by others, and how
far the road was still open to me as a gun-manufacturer. On searching
at the Patent Office I found the specification of Captain Blakeley,
dated February 27th, 1855; in this specification, Captain Blakeley
described his invention as consisting of certain improvements in the
construction of ordnance, in which an inner tube or cylinder of steel,
gun metal, or cast iron, was enclosed in a case or covering of wrought
iron or steel, which casing was made in parts, either shrunk on to a
cylindrical tube, or forced cold on to a tube, the exterior surface of
which was slightly conical, so as, in either case, to tightly grip the
inner tube, adding materially to its strength and power of resisting
internal pressure. This casing, whether made of cast-iron or steel,
might itself be further supported or strengthened by one or more outer
layers of rings or hoops, also put on under tension. Here we had
clearly and distinctly laid down the vital principles embodied in all
modern built-up guns, in this and in other countries -- that of
external compression of the inner tube by an outer one; and, unless it
can be shown that this patent of Captain Blakeley was anticipated by a
prior invention, he must stand before the world as the originator and
father of modern built-up artillery. From this patent I saw at once
that it would be impossible for me to manufacture built-up guns having
an internal steel tube, without direct infringement. Captain Blakeley,
at this early period (February, 1855), had the sagacity to see that a
steel tube or lining was an indispensible condition of a perfectly
built-up gun: not only because of its homogeneous character and freedom
from welded joints, and its
greater cohesive strength, but also because of its greater hardness and
power to resist the severe abrasion of its inner surface, caused by the
studs on the projectile moving along the rifled grooves under immense
lateral pressure. Although he knew that steel was the best possible
material for the lining of the gun, he, nevertheless, thought it
prudent to claim also the use of gun-metal and cast-iron, lest he
should have his invention evaded by the substitution of either of these
last-named homogeneous metals. He, however, evidently thought it
unnecessary to guard himself against the possible evasion of his patent
built-up gun by the substitution of a welded wrought-iron tube in place
of a homogeneous steel one. This doubtless arose from his knowledge of
the great inferiority of wrought-iron, as compared with steel, for such
a purpose, and also from his practical experience, as an artillerist,
of the searching and highly corrosive nature of the intensely-heated
powder gases, which, sooner or later, find out and deeply corrode the
numerous imperfectly-welded joints inevitable in a wrought-iron gun
tube.
The natural effects of corrosion on wrought-iron bars must have been
commonly observed. Take, as an example, an old pump-handle, and see how
the once smooth and even surface is eaten into deep grooves and furrows
by corrosion, commencing at, and following, all the lines where the
several parts, of which the bar is composed, are imperfectly welded
together. Or examine an old chain cable, the links of which were made
of smooth round iron rods, and see the indented shape it has acquired,
the once smooth surface of each link being grooved by corrosion of the
metal where the parts were imperfectly welded in the original
formation, even of the high-class iron used for cables. This is the
effect of water only on ordinary wrought iron. If any one doubts the
destructive effects of fluids more corrosive than water, let him put a
bright, well-finished piece of bar-iron into water containing only
one-tenth of its weight of sulphuric acid, and he will find that in
less than one hour he will have a perfect picture of the arrangement of
parts of which the bar is composed, showing all the imperfectly-welded
fibres, like a beautifully engraved map. What, then, must be the result
from the union of the oxygen in the saltpetre with the sulphur in
gunpowder, producing sulphuric acid gas, acting under enormous heat
and pressure within the gun, and searching out and attacking all its
welded joints?
In my search at the Patent Office, I also found the provisional
petition of Mr. William George Armstrong (afterwards Lord Armstrong),
dated February 11th, 1857, being two years less sixteen days after the
patent of Captain Blakeley, which is dated, 27th February, 1855.
Annexed is a copy of Mr. Armstrong's provisional specification, issued
under the authority of the Commissioners of Patents :-
(This Invention received Provisional Protection only.)
PROVISIONAL SPECIFICATION left by William George Armstrong at the
Office Of the Commissioners of Patents, with his Petition, on the 11th
February, 1857.
I, WILLIAM GEORGE ARMSTRONG, Of Newcastle-upon-Tyne, in the County of
Northumberland, Civil Engineer, do hereby declare the nature of the
said Invention for "Improvements in Ordnance," to be as follows :-
The improvements relate, firstly, to forming guns with the internal
tube or cylinder of wrought iron or gun metal in one piece, surrounded
by one or more cylindrical casings of wrought iron or gun metal shrunk
upon the internal cylinder.
It will be seen that this proposal of Mr. W. G. Armstrong differs from
the invention set forth in Captain Blakeley's prior patent, by
substituting a wrought-iron internal tube for a steel one. As I could
not lawfully make a built-up gun with collars or rings shrunk or forced
on to a steel tube, and as I had no intention of evading Captain
Blakeley's patent by using an inferior material for the inner tube of
the gun, I abandoned all idea of the manufacture of built-up guns, and
contented myself with supplying Captain Blakeley with steel tubes, or
with forged steel guns complete in one piece, with the trunnions formed
thereon out of the solid ingot. This manufacture I commenced as early
as February, 1861; between that date and February 5th, 1863, I had
manufactured at my works in Sheffield no less than seventy forged steel
guns for foreign service, not one of which was ever returned to me, or
was reported to be in any way defective.
All these orders for guns came to me spontaneously, and were never
sought for by travellers, advertisements, circulars, or otherwise. But
not one gun, or gun-block, was ever ordered of me by the British
Government to test the qualities of this new steel, which at that period
was the subject of the deepest interest and most careful examination by
intelligent engineers in every State in Europe.
In the early part of the year 1859, the Bessemer Steel Works at
Sheffield had regularly embarked in the manufacture of high-class steel
for tools, and also for cutlery. For this purpose I had investigated
the whole question of the supply from abroad of pure charcoal pig-iron,
and had practically tried the famous Algerian iron from Bône and other
mines, and also Indian, Nova-Scotian, Styrian, and Swedish pig-irons.
Among the latter, I found on analysis, to my astonishment, that certain
brands of charcoal pig, which, when delivered in Sheffield, cost only
£6 to £7 per ton, were, when decarburised by my process, superior in
purity to some of the highest brands of Swedish bar-iron, costing in
Sheffield from £16 to £24 per ton. One Swedish brand of pig-iron in
particular,costing £6 10s. delivered in Sheffield, was capable of
making malleable iron by my process more pure than the far-famed
Dannemora L bar-iron, worth £30 per ton in Sheffield, and with which
particular brand the small malleable iron gun which I exhibited in May,
1859, at the Institution of Civil Engineers, was made. The analysis of
this by Mr. Edward Riley has already been
given (page 182 ante).
It will be conceded that if we obtained malleable iron of this extreme
purity by my process, steel of very high quality could also readily be
produced from that particular class of pig-iron.
Thus fortified by practical working and by actual analysis, and also by
the purchase of a large consignment of this pure charcoal pig, we laid
ourselves out at the Sheffield works for the production of high class
tool steel, which we put on the market at l5s. or 20s. per
hundredweight below the ordinary trade prices for this article. My
process, so admirably adapted for the production of large ingots, was
not so well fitted to make a great number of the 2 3/4 in. square
ingots generally used in the Sheffield steel trade for tilting into
small bars, which particular size of ingot had all its
long-established trade rules and prices connected with it. So we
determined to convert our pig into steel in large quantities, and to
pour the converted metal into an iron cistern filled with water, in
order to granulate the whole charge, and avoid all costs of moulds,
casting, etc. By this means, and by the
blending of different charges in definite proportions, we insured the
production of steel of any desired temper, or degree of carburation,
with an accuracy wholly unattainable by the old crucible system. For it
must be borne in mind that in the ordinary crucible process the steel
melter has to deal with bar-iron that has been subjected for several
days, in a very large closed box or chamber, to the action of charcoal
powder at a high temperature, during which treatment the iron bars
absorb about one per cent. of carbon, more or less, dependent on time
and on temperature. The amount of absorption depends also on the
relative positions of the bars in the converting-box; hence, when the
bars are thus converted into blister steel, it is almost impossible
that the ends and the middle of any particular bar should be equally
carburised, or that bars occupying different positions should absorb an
equal quantity of carbon. After the withdrawal of the bars from the
converting-chest, they are broken into short pieces for the melting
crucible. Now the only mode of telling how far each piece of the broken
bars has been carburised is to examine the crystalline fracture by the
eye, and thus class and assort the various fragments for each quality
of steel. It is wonderful how accurately a clever practised steel
melter will judge of the state of carburation of the metal; but his
judgment, after all, can only be approximate. Such visual determination
is not like measuring or weighing the constituents of a mixture.
Crucible steel is made in separate pots of from 40 lb. to 50 lb. each,
and the steel maker cannot afford to make forty-five separate
quantitative analyses of every ton of steel he turns out. Even if he
could do so, after he had made the metal into ingots, he would not be
more secure, since he could not alter the ingot when once cast. As a
matter of fact, the precise degree of carburation of each 50lb. of
steel produced in the old crucible process depended on the judgment of
a man looking at the crystallised fracture of each piece he put into
his crucible; and all must agree that it is highly creditable to those
engaged in this mere guesswork that they got as near as they did to the
quality required.
In the manufacture of tool steel, on the system which I laid down at my
Sheffield works, we entirely eliminated this source of inequality, by
dispensing with ocular examination of a crystalline fracture, which
is subject to numerous modifications in character, from causes other
than its precise degree of carburation. We converted five tons of pig
iron at one charge, and having granulated it by pouring the molten
steel into a cistern of water, we had this quantity of shotted metal in
a condition that was still practically fluid as far as the power of
mixing was concerned. If each granule weighed, on an average, seven
grains, we had in our 50 lb. crucible 50,000 separate pieces, the
precise degree of carburation of which had been ascertained by careful
quantitative analysis of the whole five tons, which analysis we could
afford to make -- and did make -- very carefully.
We produced, as nearly as practicable, three qualities of converted
metal, say A, with half per cent. of carbon, B, with one per cent, and
C, with one and a-half per cent.; we also made pure iron upon which we
could absolutely rely. These four qualities, accurately analysed, were
kept in separate bins; the analyst who gave the order to the steel
melter to make two or three tons of steel of any precise and
predetermined degree of carburation would, say for example, weigh 41
1/4 lb. out of bin A, and put 8 3/4 lb. from bin B into it, thus making
the 50 lb. charge, always using the nearest of the three qualities to
the one required, and making it a little milder or a little more highly
carburised as desired. Most minute differences could thus, at all times,
be made with unerring certainty by the simple fusion in a crucible
of two metals, the carburation of which had, in each case, been tested
by careful analysis. The mixing of these accurately-ascertained
qualities in definite weights while in the granulated state resulted
in the production of a quality the exact mean of the known constituents
of the two qualities mixed. It gave a more certain and a more accurate
result than could possibly be obtained on the old system of crucible
steel-making, where judgment by the eye took the place of accurate
analysis and the weighing machine, as used in my system. Hence it was
an undeniable fact that we could, and did, produce commercially
crucible cast steel of great purity, and of any precise and
predetermined degree of carburation, with greater accuracy than was
obtained by the method employed to produce crucible steel in Sheffield.
Barrels made from Bessemer Steel by Thompson's Patent process.
Barrels, 1853 Infantry Pattern, .577 bore. Bullets used, 715
grains. Diameter, .551 Length, 1.043. Ratio of length to diameter.
1.893.
Result of Experiments:
1st round, charge 205 grains, 7 1/2 drachms powder, 1 bullet.
2nd round, charge 224 grains, 8 1/4 drachms powder, 1 bullet.
3rd round, " " 2 bullets
4th round, " " 3 bullets
5th round, " " 4 bullets
6th round, " " 5 bullets
The barrels were now examined and found intact.
7th round, charge 224 grains, 8 1/4 drachms powder, 6 bullets
8th round, " " 7 bullets
9th round, " " 8 bullets
10th round, " " 9 bullets
11th round, " " 10 bullets
12th round, " " 11 bullets
13th round, " " 12 bullets
14th round, " " 13 bullets
15th round, " " 14 bullets
16th round, " " 15 bullets
Barrels found intact.
17th round, charge 224 grains, 8 1/4 drachms powder, 16 bullets.
The firing was now continued with one barrel only, the nipple having
been blown out of the other, which, still retaining its charge of 16
bullets, remained intact.
18th round, charge increased to 269 grains, 9 3/4 drachms powder, 17 bullets.
19th round, " " " " 18 bullets.
*20th round, " 413 " 15 " " and 25 bullets.
The barrel was then examined and found intact. Further test was deemed
unnecessary. Proved by Mr. Samuel Hart, Assistant Proof-Master, *in the
presence of Ezra Millward, Esq., Proof-Master at Birmingham, December
23rd, 1863.
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