From 18G1 to 18C5 Mr. Fairbairn was engaged in
aiding the Government on an official investigation respecting
the application of iron to defensive purposes in warfare. The present
construction of the iron armoured vessels of our navy has all arisen out of
this enquiry; and on account of the great public interest and importance of
the question, it demands a notice at some length.
It is necessary to give a short preliminary
account of the circumstances which led to the investigation.
Some twenty years ago it began to be perceived
that a great change must be made in the construction of ships of war, in
consequence of the introduction into heavy artillery of rifled shell. The
'Wooden Walls of Old England,' which had done such good service from the
time of the Spanish Armada to that of Trafalgar, were powerless against the
long range, the accurate aim, the penetrating power, and the destructive
effect, of these deadly missiles; and it was seen that unless something
could be done to meet the difficulty, the efficiency of our navy must be
The use of iron was one of the most obvious
modes of resisting the penetration of shells ; but hitherto the application
of this material had not found favour with the naval authorities of the
It has been mentioned in earlier parts of this
work how actively Mr. Fairbairn had exerted himself in introducing iron
ship-building. The first application of this material had been for
mercantile purposes, but in 1835-6 he had arrived at the conclusion that
wrought iron was the safest and most durable material for naval
constructions also, and he was anxious to impress on the Government the
advisability of its being employed for vessels of war. lie was, at an early
stage of the manufacture, in communication with the Admiralty, and he urged
that iron ships, if applied to war purposes, would be not only superior in
power, but safe under all the circumstances of attack and defence.
There was at that time a great deal of ignorance
and prejudice in regard to the use of the new material. Many people (among
them persons of influence in naval matters) conceived that the flotation of
a timber ship was due to the fact of wood being lighter than water, and
seriously argued that if a heavy material, like iron, were substituted, the
ship must inevitably go to the bottom This argument was of course met in a
simple way by the direct logic, of facts, inasmuch as iron ships, which did
really float, were m existence; but there were other objections less easily
disposed of, and one of the most formidable was the great damage likely to
be done to the iron plates by heavy projectiles. In a ship with wooden
sides, a shot hole was not a very serious matter; ir seldom made a great
leak, and the hole could easily be plugged up. Hut a shot blow on iron
plates rent them open with a fearful gash incapable of stoppage. It was
suggested that this evil might be diminished by backing the plates with soft
or elastic substances, and some experiments were tried, in 1840, by the-
Admiralty at Portsmouth with this view; but the results were so unfavourable
that they were deemed conclusive against the adoption of iron vessels for
war purposes, and the Government stood aloof from the general movement,
deciding to limit the construction of iron vessels to the. mail and packet
Still, however, in regard to wooden ships, the
awkward difficulty remained of their destractibility by the new rifled
shell. With solid shot the improved artillery woidd have been much less
formidable. The entrance of a solid shot into a ship, was an event always
expected in action ; and though it often did much damage, it did not destroy
the ship, which was capable, in brave hands, of holding out for a long
defence, even though 'riddled,' as the expression was, by the fire of the
enemy. But large shells, bursting out like fierce volcanoes among the
timbers of the structure, or scattering between the decks showers of
fragments of jagged iron, every piece dealing destruction in its path, made
such havoc as no bravery or skill could hold out against; and a wooden ship
efficiently attacked in this way must, in a very short time, either blow up,
or sink, or surrender.
Shells, in themselves, were no novelties; they
had, long before the introduction of rifled guns, been used for bombardment
with mortars, and had even been introduced as projectiles from ordinary
cannon ; but from the. uncertainty of aim and want of force when fired from
a distance, and from the imperfect construction of the missiles themselves,
they were not much more effective against ships than ordinary cannon balls.
It was only when rifling enabled them to be fired at long range, with great
accuracy and powerful impact, and when the improvements of their
construction gave full scope to their destructive capabilities, that they
became so formidable.
The use of timber ships being retained, there
remained the alternative of casing them with an armour of iron plate, of a
thickness which shells could not penetrate. There were many difficulties in
the way of this, and the first person who made any successful efforts to
overcome them, was the late Emperor of the French. At the time of the
Russian War, when rifled guns were first beginning to assume importance,
Napoleon III. saw the necessity of an impenetrable armour, and quietly
pursued experiments and investigations on the subject till he had succeeded
in building three floating batteries, which were protected by thick plates
of iron. They we're sent out to the Black Sea, where they arrived shortly
before the conclusion of the war, and they were employed by the French in
the allied attack upon Kinburn, on October 17, 1855. .
These batteries were exposed to a heavy fire, at
a distance of 700 yards, for about three hours, unsupported by the fleet;
and though some casualties occurred from shell and shot entering the large
old-fashioned port-holes, yet the vessels themselves were comparatively
uninjured. This success, so creditable to the skill and perseverance of our
ally, settled the question of the practicability of defending ships of war
by iron armour; and in France the further development of the principle was
soon rapidly pushed forward.
In England, however, the authorities were loth
to distrust their time-hallowed wooden walls; and although the subject was
looked into, very little was seriously done. In 1858, two floating batteries
were experimentally cased in iron plates, in imitation of the French
batteries at Kinburn, and were fired at for trial. Iron plates were also,
about the same time, placed experimentally on the sides of some of Her
Majesty's ships, and Mr. Whitworth's new rifled ordnance, with steel
projectiles, were used against them. The result demonstrated the value of
the protection, though it showed much imperfection through want of
In the mean time the French, profiting by their
experience at Kinburn, pushed on vigorously, and, a year or two after the
Crimean War, had completed a frigate plated with iron armour, which was
named 'La Gloire,' and was launched about 1859. She was timber-built,
resembling one of our line-of-battle ships cut down, and was cased from end
to end with iron plates inches thick; she was 250 feet long, and was
propelled by a screw, with engines of 900 horse-power.
When the news of the construction of 'La Gloire'
reached this country, our Government became alarmed, and naturally so; for
she was a formidable challenge to our navy. Accordingly, early in 1859, the
Admiralty determined, in great haste, to build a ship to approch her, and
they laid down the celebrated iron-plated frigate the 'Warrior,' which was
built with great celerity, and was launched in December 1860. This ship was
much larger than her opponent, being 380 feet long, 6,000 tons burthen, and
having engines of 1,250 horse-power. Her armament was much heavier than that
of 'La Gloire,' and her speed much faster. She differed also materially from
the French ship, in that she was built of iron instead of timber. The
Government had, as already stated, arrived, twenty years before, at the
conclusion, that iron was an unfit material for ships of war; but the
subject had since been much discussed, and the opinions of scientific naval
constructors in its favour had been urged so strongly, in opposition to the
prejudices of the Admiralty, that they were induced, almost against their
own will, to fall in with Mr. Fairbairn's original recommendation. This has
since become universally adopted, and wooden ships of war are now things of
Although, however, there was no timber hull to
set on fire, yet the thin plates were easily penetrable both by shot and
shell, and hence it was as necessary to protect an iron as a wooden ship.
But nothing was known experimentally as to how the iron armour could be
applied, our authorities having wasted, in indecision, the time that the
French Government had employed in investigation and experiment.
In this state of ignorance our designers
considered they could not do better than repeat the plan they had followed
with the floating batteries, namely, copy from the French as nearly as they
could. They, therefore, first made the hull of the ' Warrior' represent that
of 'La Gloire,' by fastening, on the outside of the iron skin, a thick
cushion of timber, on which they proceeded to iix the plates by bolting.
They introduced certain novelties into the details, which, however, were
afterwards found to be no improvement, but rather inferior to the French
On the finishing of the ' Warrior,' the
Government bethought themselves that it would be desirable to do what they
ought to have done five years before, namely, to ascertain something about
the principles which should guide the design of iron armour. In other words,
having already built the ship, they began to enquire how they ought to have
built her (a curious line of policy which, it will be seen, was repeated in
an analogous case a few years later). It was apparent that the use of iron
for such a novel purpose was so complicated by considerations of a
mechanical and metallurgical character as to demand a more searching
technical investigation than it could receive at the hands of purely
military or naval authorities; and at the end of 1860 the Government wisely
determined to submit the whole matter to a mixed special committee. The
Secretary-at-War, Mr. Herbert (afterwards Lord Herbert) therefore selected
six gentlemen, and, having obtained their consent to act, the Committee,
called the 'Special Committee on Iron,' was formally appointed on January
12, 1861. The members were:—
Captain (afterwards Sir John) Dalryrnple Hay,
chairman, to represent the Navy.
Major Jervois, R.E., to represent the Royal Engineers.
Col. W. Henderson, R.A., to represent the Royal Artillery.
Dr. John Percy, F.R.S., the eminent metallurgist
Civil Engineers, specially
Mr. William Fairbairn, F.R.S.
Mr. William Pole, F.R.S., experienced in the uses and properties of iron.
The Committee were actively at work four years,
during which time they presented to the Government four Annual Reports, each
accompanied with a large volume of minutes of experiments and proceedings.
The information contained in these volumes was of the greatest value, but
unfortunately they were never published. The Government, although no
particular secrecy had been observed in the proceedings (foreigners having
been often admitted freely to them), were reluctant to make the mass of
knowledge gained public property, and accordingly only-extracts and
abstracts were made known from time to time.
It is, however, no breach of confidence, after
this lapse of time, to give a summary of the principal matters that occupied
the Committee's attention.
Their first duty was to collect and classify all
the meagre information that existed, and the results of all the experiments
that had been made on the use of iron for resisting shot.
They then called before them various persons
whom they considered likely to have knowledge of the subject, military and
naval officers, engineers, ship-builders, and iron manufacturers; and their
evidence, given very fully, was recorded find considered. But the great
diversity of the opinions thus gathered showed the obscurity in which this
novel application of the material was involved.
The Committee then commenced an elaborate series
of investigations and experiments systematically carried out; first on a
small scale on single plates of various sizes and thicknesses; and then on
targets of large size, made to represent actual ships' sides, of a great
variety of constructions. These enquiries extended over several years, and
led to the establishment of many important principles as to the nature of
the material best adapted to the purpose; the arrangement and dimensions of
the armour; the mode of fastening to the ship; the effect of the iron and
material of the shot; and so on. It may be interesting to give an account of
some of the trials made and the results arrived at on these points.
One of the most important considerations was as
to the nature of the material best fitted to be used for armour; for as this
was capable of being given many varieties of character, according to the
mode of its preparation, it was desirable to ascertain which was best for
the purpose in view. On this point the opinions of the witnesses had varied
a good deal, but there had been a general impression that one of the most
important qualities to give was hardness. It was urged that the harder the
armour was made the better would it resist the shot, and that in fact the
best material, if it could be made and applied conveniently, would be hard
steel, or at least a combination of steel and iron.
This was a plausible idea, but it was not borne
out by investigation and experiment. It was found that hard plates were
brittle, and were broken up by the blows, when the detaching of the
fragments exposed the vessel to penetration; soft plates, on the contrary,
gave way, and became dented, bruised, and distorted, but still held together
and formed an efficient protection.
Both theoretical considerations and practical
experiments showed that the best principle of defence was not to attempt to
resist the blow, but to receive it in such a way as would do the least
mischief. The obvious mode of accomplishing this with iron armour was to
make it of soft, tough plates, which would allow the energy of the shot to
be expended in indenting and battering them without producing fracture.
The Committee, therefore, came to the conclusion
that the best material for armour was wrought-iron, free from hardness and
brittleness, but as soft and tough as could be procured. This opinion,
though it was arrived at in opposition to the ideas generally prevalent, has
been fully confirmed by subsequent experience.
The mode of making the plates also engaged the
attention of the Committee. It was a new thing in the iron trade to
fabricate plates of this enormous size; and the first attempts were
imperfect, the iron being of inferior quality. The Committee requested the
principal houses to produce plates for trial, invited them to witness the
experiments, and gave them every aid in their endeavour to perfect the
manufacture; and the result was a marked improvement and a much better
approach to the quality required.
Two processes were used for making the plates—
hammering and rolling. In the former, large lumps of iron, previously
prepared from 'scrap' or from 'puddled bars,' were brought to a welding
heat, and being laid together, were placed under heavy steam hammers, the
repeated blows of which welded the masses together, and shaped them to the
required form and dimensions. This process was the first adopted for the
manufacture of armour plates; it was used by the Thames Iron Company, who
built the 'Warrior,' and the plates of that ship were made in that way.
Shortly afterwards a firm in Yorkshire adopted
another plan, namely, by rolling—a process in tact the same as that used for
ordinary boiler-plates, but on a much larger scale. The masses of iron,
first prepared, were fiat iu shape, and several of these, being laid one on
the other, were heated to the welding point in a furnace, and then passed
between large rollers, which rolled them out into one solid plate of the
required size. The process was a difficult one, from all the apparatus
requiring to be of such great size, and the machinery of such immense power.
The Iron Committee tried extensive experiments
on plates made by both these systems. They found the hammered plates had a
tendency to be hard and unequal. The repeated blows of the hammer hardened
the material, and this effect was not always the same in different parts,
some receiving more action than others. Moreover, from the irregular form of
the primitive masses, the parts were not always perfectly welded together.
The rolled plates, on the other hand, from the more uniform and less sudden
action of the compressing force, were softer and more uniform in quality,
but they still had the defect of what was called 'lamination,' i.e. a want
of perfect welding between the different layers. The Committee, on the
whole, preferred the rolled plates, and this mode of manufacture has now
superseded the other almost entirely
Another point investigated by the Committee was
the effect of the form and material of the shot. They considered, however,
that too much importance had" been attached to these particulars. The shot
was merely a means of transferring to the plate a certain amount of
mechanical energy generated at a distance by the powder; and the orly way in
which form and material influenced the result was by causing a greater or
less proportion of this energy to be absorbed by the shot itself, and so
wasted, or diverted from its intended purpose.
It was attempted by a very ingenious process to
ascertain the amount of work absorbed by the shot. It was found that, after
striking the plates, the shot, or the fragments of them, became highly
heated, and, according to the recently established thermo-dynamic law, by
measuring the rise of temperature, an approximate estimate could be given of
the work absorbed. It was thus found that with a hard-tempered steel shot,
the energy expended upon the projectile was about one-tenth of that stored
up in it at the moment of striking; while with softer steel it was
two-tenths; with soft wrought-iron it amounted to above one-half of the
whole ; and with cast-iron to probably still more.
These results, which were fully corroborated by
the effects produced on the plates, pointed to hard steel as the best kind
of shot to be used against iron armour ; but this expensive material was
afterwards superseded, in consequence of a discovery made by Capt. Palliser,
that cast-iron shot would answer, if made of a particular quality, and in a
particular form. In the ordinary shapes, shot of cast-iron, whatever the
quality of metal, broke up with great facility; but Capt. Palliser showed
that if the head were made pointed and the metal were very hard, the shot
would penetrate the plate before breaking, and the minimum amount of work
would be lost on the projectile. The shot so designed was accordingly
adopted in the service.
The Committee further investigated the laws of
resistance offered by plates of different thicknesses to projectiles of
different natures and weights, and with different velocities. Reverting to
the principle that the damage to the iron plate was proportional to the work
in the shot, or to the charge of powder, it was assumed that some definite
estimate might be made of the thickness of plate necessary to resist certain
artillery. As far as could be made out, there appeared reason to believe
that, within certain limits, the resisting power of a plate bore a tolerably
near ratio to the square of its thickness; but there was so much difficulty
in estimating the amount of damage done, and the quality of the plates tried
was so variable, that no trustworthy relation could be fixed. In heavy
plates, moreover, practical effects came in which disturbed the application
of any general law.
Another question that occupied the attention of
the Committee was what form it was most advantageous to give to the
defensive material. Several forms were proposed, such as bars, superposed
thin plates, corrugations, ribs, bosses, and many other ingenious
contrivances. More than four hundred of such plans were submitted to the
Committee ; and a great many were fully considered and tried; but, through
all these complications, they arrived at the. simple result that the best
application of the material was a single plate of uniform thickness, with
the surface perfectly plane.
Great interest and importance were attached to
the mode of applying the iron armour-plates upon the h ill of the vessel In
the ' Warrior,' as already explained, a cushion or bed of timber about
eighteen inches thick had been interposed between the armour plates and the
iron skin of the vessel, a plan followed, probably, more for the purpose of
imitating the construction of 'La Gloire,' than with any very definite idea
of what object the wood was to serve.
Many objections were raised to this by persons
of considerable authority in ship-building and mechanical science. It was
said that the plates had better be fastened at once upon the iron skin, and
that the wood backing was not only unnecessary, but was absolutely
prejudicial, as liable to decay, and to destruction by fire and shells. It
was necessary to test this, and no less than three expensive targets were
constructed for the purpose.
The result of these trials was to convince the
Committee that the wood backing performed several important functions,
which, though they had not been foreseen, were of much advantage.
In the first place, by its softness, it deadened
the jar and vibration caused by the blow of the shot. In the iron targets
this was severely felt, breaking the bolts and rivets, and shaking and
damaging the structure generally ; but with the interposition of the soft
cushion these evils were much reduced, and the structure was greatly
Secondly, it had the advantage of distributing
the effect of the blow over a much larger area of the skin plate. When the
armour was fastened directly upon the skin the shot acted upon a small area,
which gave it a better chance of penetrating; but with the large thickness
of wood between, the area of operation enlarged backwards, like a cone,
thereby increasing materially the power of the thin skin to resist the
Thirdly, if. under heavy fire, the armour-plate
became broken, the pieces did not fall off, but became imbedded m the wood,
and were thereby hold in their places, retaining their utility of defence in
a considerable degree.
Fourthly, the wood was useful in catching what
is called 'langrage,' or pieces of shot and shell, and preventing their
entering the ship.
For these reasons the Committee recommended the
retention of the wood backing to the armour, and it has ever since formed an
essential feature of naval defence.
The best sizes of armour plates, the process of
bending them and adapting them to the form of the ship, and the modes of
fastening them to the hull, and securing them in their places, also received
the consideration of the Committee* and were fully reported on.
The Committee wished to carry their experimental
investigations so far as to put the ' Warrior' herself under the fire of
heavy guns. This was thought too expensive and troublesome a proceeding, but
the case was met by the construction of a target, about 20 feet long and 10
feet high, which was made exactly a counterpart of a portion of the ship's
side. This target was erected at Shoeburyuess in 1801, and was fired at with
the old 68-pounder gun, and with the Armstrong rifled ] 10 and 120-pouuders,
the maximum charge of powder being 20 lbs. It received altogether, from
these guns, twenty-nine rounds, the combined weight of the shot being 3,229
It was, of course, a good deal damaged at the
front, but it was not penetrated, and would still have afforded efficient
protection. This result, considering how small an area the fire was
concentrated upon, was very favourable, and showed that the ship's armour
was strong enough to resist guns of the size then used.
The Committee also experimented cm many other
targets of different kinds, made to represent ships' sides defended by
different iron constructions. One of these was designed specially by Mr.
Fairbairn, for the purpose •of testing certain views held by him.
The experiments were carried on for the most
part at Shoeburvness, where it was possible to get a large area of free
ground, and where the artillery depots enabled the Committee to obtain the
most powerful guns and the most skilled gunners. The trials involved a great
deal of risk, but by admirable precautionary arrangements no accident ever
Mr. Fairbairn, in addition to a frequent
attendance at the meetings and experiments of the Committee, undertook, at
their request, some special investigations for them, reports of which were
published in their proceedings. These were:—
On the Mechanical Properties of Specimens of the
Iron and Steel Plates subjected to Experiments with ordinance, their
Strength, Ductility, Resistance to Punching Force, &c.
In 1862 :—
On the Resistance of different kinds of Shot to
a Force tending to crush them, and the forms they assume under Pressure.
Experiments on Punching.
In 1863 :—
On the Mechanical Properties of Iron Plates.
On the Manufacture of Armour Plates.
Experiments to test the value of annealing Armour Plates.
On the Tenacity of Cast-Iron Shot.
On the Mechanical Properties of Iron Plates.
On the Manufacture of Armour Plates.
General Summary of Results.
In these investigations he was ably assisted by
Mr. Unwin, whose services in the matter were specially acknowledged by the
Mr. Fairbairn communicated information on this
subject in two papers read before the British Association in 1861 and 1862 ;
at a lecture at the Royal Institution in 1862; and in a memoir to the
Institution of Naval Architects in 1869.
In December 1867, the War Office called the Iron
Armour Committee together again, with the addition of some other members,
for the purpose of investigating the construction and properties of certain
large iron shields for land defences which had been sent out to the forts at
Gibraltar and Malta.
As iu the case of the 'Warrior,' previously
mentioned, the Government had first made the shields, and afterwards begun
to consider how they ought to be constructed. To enlighten themselves on
this point, they had one of the shields fired at, and it proved so weak
that, in alarm, they appealed to the Committee, who, after due examination,
reported unfavourably of the strength and construction of the shield.
Mr. Fairbairn attended some of the meetings, but
his great age and infirm health prevented his taking a very active part in