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Henry Harrisse.

Britain at work; a pictorial description of our national industries online

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and revolving shafts and cranks, until the
senses deaden, and the mind reels in the
effort to grasp it all. From the steel works,
where the huge ingot of steel comes glowing
at white heat from the furnace to meet the
irresistible grip of the 6,ooo-ton pressure
hydraulic press, to the delivery shop, where
the finished gun awaits the firing tests, all
is order and design, as precise in the smallest
minuti;e as comprehensive in the general
scheme. Huge boring machines bore an
absolutely flawless steel gun-barrel weighing



TIIK MAKING OF BIG GUXS.



225



up to 40 tons to the fineness of a i,oooth
part of an inch. A titanic gun, whose
projectile will devastate a city, is built up
with a watchmaker s skill. The visitor
leaves the works with an overwhelming sense
of their tremendous energy, and a profound
impression of their creator s genius ; but the
central idea he carries away is the perfect
union of strength and precision which he
.sees everywhere around him. The ordnance
works are infinitely great and infinitely
little, and if genius is the art of taking
pains then the gun-maker is the greatest
genius of us all.

At Klswick over fifty large shops (including
the steel works) are devoted to the making of
guns, these shops covering over fifty acres,
employing a busy army of from 15,000 to
16,000 men, and turning out an average of
eighty-five guns of all sixes and types per
month, besides mountings, carriages, turrets,
and ammunition. The enormous value of
this work may be judged Irom the fact that
a 5o-ton gun is worth more than .10,000,
and the mountings as much more.

Like the battleship for which it is in
tended, like all things great and strong, the



modern big gun is of slow growth. Its
parts pass through almost incomprehensible
stages in the process and manufacture, and
are subjected to test after test, and then are
slowly, and with the utmost care, pieced
together, only to be subjected to more tests
before finally leaving the makers hands. It
takes from ten to twelve months to make a
12-inch Armstrong gun. Its birth begins in
the melting-furnace, where Siemens-Martin
steel of the finest quality is subtly com
pounded of the best Swedish iron, rich oxide
ore, and ferro- manganese, and emptied,
molten and glowing, into a great casting
ladle, from which it runs into the moulds,
and is slowly cooled into ingots of from 2O
to 40 tons. The ingot from which the barrel
of a 12-inch gun is made weighs over 40 tons.
Measuring 13 or 14 feet in length when it
comes from the furnace, a hole is bored through
it, and it is then compressed and drawn out
in the powerful hydraulic press which works
up to 6,000 tons pressure, until it measures
three or four times that length. Before the
elongated ingot leaves the steel works it is
rough-turned in a heavy turning machine,
and, most important detail, a disc is cut off




*%5^ *



29



i-our.ixc, A r.rx Tt BK.

(/ ; -in a fh-t^rnfh sufflicd by .1f,-SM-s. Camiiie. t & So -.s. 1.1,1., :



22fc>



BRITAIN AT WORK.




will stand
mancnt set is
square inch in the



without pcr-
21 tons per



ROUGH-TURNING A GUN-BARREL IX TURNING MACHINE.

(Photo supplied by Sir- IT. G. Armstrong, Whitworth & Co.)



each end in order to test the quality,
elasticity, and tensile strength of the steel,
for if that should fail a new ingot would
have to be worked.

Before the hollow, rough-turned cylinder
goes further, then, the steel discs cut from
it are severely tested. Out of these discs
there are cut several testing pieces about
four inches long, with heads resembling short
double-headed bolts, the hydraulic testing
machine taking hold of the bolts at either
end. The tests are made in a little office
not far away, where stands a machine which
does not take up much more space than a
copying-press, but has tremendous power.
The first duty of those conducting the
tests is to note when the steel commences
to move or yield as it begins to elon
gate under the stress to which it is
subjected ; then a piece is elongated until
a point is readied when the steel ceases
to return after expansion to its original
length ; and, finally, the breaking stress is
ascertained by adding weight until a test
piece breaks. A self- registering apparatus
is attached to the bolts in the first two
tests.

The first test shows that the steel began
to move at a pressure of 15 tons to the
square inch ; the second proves that
the amount of the strain which the steel



bolt

two inches long the measure
of elongation is found to
be just under half an inch ;
and the third shows that
it breaks at 36 3 tons per
square inch. In the case
of a big gun, say 50 tons,
the minimum requirements
of the Government are
yielding strain i i to 15
tons to the square inch ;
amount of elongation, above
15 per cent, of the length
tested ; and breaking strain
between 27 and 35 tons
per square inch. These
tests refer to the steel in
o.\ its soft state, as it comes

from the steel works.
Similar tests with other bolts follow, upon
their being hardened by heat and tempered
by being plunged into oil. At this last
series of tests the minimum requirements
for a similar gun are these : Yielding strain,
25 to 33 tons to the square inch ; amount
of elongation, above 10 per cent, of the
length tested ; and breaking strain, 38 to
48 tons per square inch.

Assuming that the tests are satisfactory,
as they were when the writer saw them, the
boring of the gun is the next operation.
At the first " cut " 9}^ inches are taken by
a circular cutter out of the centre of the
cylinder, which has an outside diameter of
about 21 inches. With the barrel 30 feet
long the rough boring occupies more than a
week, although the machine works day and
night. The borer or cutter, which is carried
on the end of a substantial shaft, advances
at the rate of 4 3 4 inches per hour, that is
assuming it could be kept at work con
tinuously, but, as a matter of fact, it is
frequently withdrawn to admit of the
examination of the bore and ensure the
accuracy of the " cut." Although it has
behind it a powerful pressure, and cuts the
hardest steel like so much cheese, the bore
travels silently, and with singular slowness.
This slowness means economy and care. The
slightest irregularity in the progress of the



THE MAKING OF BIG GUNS.



227



borer over any part of the cylinder might
easily mean the complete ruin of the ingot.
Having been rough-bored, the barrel is
toughened by being heated and tempered
by being clipped in a pit of oil, operations
naturally involving the use of heavy
hydraulic cranes, which are all over the
works. Then comes the difficult and tedious
process of " fine-boring-." The fine-boring
comprises three separate borings, and in the
case of a 12-inch or 5o-ton gun the rough
"cuts " in this stage take two or three weeks
each. In the final boring from jooth to
i7,th of an inch, according to the gun, is left
to be taken out. This operation requires
the greatest care. If the bore becomes torn
or damaged by the breaking of a tool or
seizure of the boring head, a barrel which
may now be worth between ,2,000 and
,3,000 is utterly spoiled.

The barrel, having- been fine-turned in the
lathe on the outside, is reach to receive the
outer coats of steel with which a gun is
built up. A gun is really a succession of
cylinders of steel shrunk over each other,
and each cylinder has to be treated in almost
exactly the same fashion as the barrel or
central tube that is to say, has to be tested,
turned, rough- and fine-bored, and gauged
carefully throughout, to ensure correctness
of diameter. To attain perfect accuracy in
all these borings is no easy matter, par-



ticularly in the case of the central tube, for
as the cutter of the bore wears down as it
approaches the end of the cylinder, the
diameter of the tube diminishes. The
12-inch gun consists of five cylinders or
layers, or four beyond the barrel. These
cylinders run in thickness thus: Barrel, 4 \
in.; second course, 5 in.; third course, 3 } 4
in.; fourth course, 3 ] 2 in.; fifth course, 4 ; ,
in. The gun is thickest over the powder
chamber about 19^ in. because it is the
seat of the explosion. In the guns made for
our national service the barrel is covered
from breech to muzzle with layers of wire
or with long cylinders of steel, the muzzle
being finished off with the old-fashioned
muzzle-swell. In the older patterns of guns
all the cylinders, except the inmost one,
were in short lengths; the iio-ton gun
comprises no fewer than forty -four pieces,
apart from the breech - screw and the
mechanism for closing it. The number of
tests which this division of the gun into
forty-four sections involves is striking enough.
The barrel is credited with twelve tests for
each end 24 ; the other 43 pieces have four
test pieces taken from each end 344. Thus
the total number of tests made in the case
of each separate gun is 368.

The cylinders are affixed to each other
by the process known as shrinkage. The
bore of the cylinders (apart from the original




WIRING A RIG- Or\.

(.Phota supplied ly Sir IT. G. .lri<.tron~. U hihvortn & Co.)



228



BRITAIN AT WORK.



tube or barrel) is always made slightly less
than the outside diameter of the cylinder
which it has to cover. Expanded by the
application of heat, the outside cylinder or
"jacket" is easily slipped over the inner tube,
and as it gradually cools the jacket grips
with great power the inside cylinder. When
the gun is thus being built up it stands in
a pit, where the cylinder jacket next to
be placed upon it is brought by a hydraulic
lift from one of a series of furnaces heated
by gas and dropped over it. With a shield
over it, it then gradually cools, measures
being taken to ensure that it cools in a
uniform fashion. The grip of the cylinders
upon each other grows in severity as the
outside of the gun is reached, and the com
pression upon the original cylinder, of course*
increases with each layer added. This fact
discloses the application of an important
principle in gun-making.

In a natural way the great strain following
upon the explosion of the charge of powder
would fall heaviest upon the inner cylinder
(or barrel), in which the explosion takes place,
and the outer cylinders would only experi
ence it in a diminishing degree, in a degree
which diminishes so rapidly, as it approaches
the exterior part of the gun, that it might
almost be said to have disappeared by the
time it reaches the outside parts, for, as it
will be clear, there is a point under such
circumstances where thickness ceases to add
strength. By subdividing the gun into
cylinders, each cylinder having been put
into a high state of tension by being shrunk
on brings the full measure of its power to
withstand strain to the support of the inner
cylinder or bore, and the other parts of the
gun, that is, each successive layer, reinforces
the accumulated resisting power of the whole
mass. A further consequence of the system
of shrinking the cylinders one over the other
is that the compression experienced by the
original cylinder or barrel is so severe that
the outer cylinders, owing to their being
in a state of tension, first take the strain
created by the explosion, and as the
outer cylinders expand or extend fas the
quality of metal guarantees that they will
do), the strain is progressively imparted to the
original tube, which ultimately receives its
allotted proportion.



It was to further distribute the strain
over the whole gun that the wire or steel
riband gun was adopted at Elswick with
such success. Great additional strength and
security are gained in a gun through con
struction by means of ribands. The gun is
also lighter than one built in the ordinary way.
The building-up of a gun in ribands minimises
the danger from fla\v, for even should a flaw
escape observation when the riband is being
bound on, it is confined to a small area,
permits of the employment of steel of greater
strength than is attainable in the ingot
form, and secures more fully and efficiently
than is possible in the usual form of manu
facture the measure of tension in the steel.
If our gun is a wire gun, then, which it is
nowadays pretty certain to be, the process
of wiring must begin when the first steel
cylinder barrel is so far finished as to be
reach for its jacket. Before that is shrunk
on, the wiring has to be done. The riband,
which is apparently rather more than a
quarter of an inch broad and not half that
thickness, is wound on cold from a drum. The
gun, revolving slowly, draws the riband from
the drum, while the drum is controlled by
a brake to ensure that the wire is brought
into a full state of tension. The strain
varies with each layer of riband, these strains
being determined by the brake apparatus
attached to the drum shaft, which regulates
the amount of tension required for each
successive layer. In the lo-inch gun there
are fourteen layers of riband. The riband
portion of the gun is covered by a casing
of steel. The id-inch riband gun has a
thickness of walls of 1 1 inches, of which
3 inches is of steel riband. In some of
the larger guns as much as 100 miles of
riband are coiled up between its cylinders.

Bored, wired, jacketed, a composite whole,
the gun must now be " rifled." The rifling is
one of the most interesting operations in the
series. The cutter is directed in its twisted
movements by a pinion and rack, which in
their turn are acted upon by wheels rolling
along a slightly curved track or framework
of iron. The cutter appears to travel along
the barrel at a quicker rate than does the
boring bar when a gun is being bored ; but,
although the rifling only extends up four-
fifths of the length of the gun, the operation



230



BRITAIN AT WORK.




J hoto ; Gregory

A \YIRKD GUN IH.ACKn IX POSITION" FOR

occupies a week to a month, according to
size, with the machine working continuously.
The pitch of the rifling is progressive, and
with a 43-ton gun the cutter will make one
turn in every 30 feet. The cutter which
only cuts in coming out goes up each
groove from eight to twelve times, according
to the hardness of the metal, and, as there
are eighty grooves, in many instances it
travels along the gun eight hundred times.
The greatest conceivable care has to be
exercised in the rifling of big guns, as the
slightest departure from the true course
may now destroy material and work worth
together ,10,000 or ,12,000.

The gun now remains to be "chambered"
and fitted with the breech - screw. The
chamber, which is enlarged by a subsequent
boring after the bore is completed, is bottle-
shaped ; it does not meet the bore abruptly,
but the two diameters are joined by easy
curves. The gunmaker seeks to avoid a
long chamber, as it gives scope for wave
action on the part of the powder-gas, with
the result that excessive local pressures are
created. The breech-piece of the big gun is
connected with the breech-end of the gun
by a hinged platform. The breech - piece
or breech-screw of the i lo-ton gun draws
out from the gun on to a sliding tray. In
all cases the breech-screw or breech-plug is
fastened in the breech-end of the guns upon
what is known as the interrupted screw



system, that is, the breech-
plug and the breech-end of
the gun are cut into corre
sponding screw-grooves, only
for these to be subsequently
taken out to the extent of
one-half in opposite quarter-
sections, so that the breech-
piece is easily pushed into
the gun the scre\v parts or
the breech-piece passing into
the indented sections of the
breech-encl, and vice versa
and the screws drawn into
each other by a lever. The
interrupted screw is really
an ingenious form of lock.
The screw in our gun is 18
to 20 inches long.

The fixing of the breech-
piece demands great skill. The precision
of the fit is a vital point. It is an absolute
necessity to prevent the escape of the powder-
gas from the powder-chamber through the
breech-pieces. The escape of gas through
the breech is prevented in this way : An
annular canvas bag, filled with asbestos and
suet, is placed between the front of the breech-
screw and a strong steel bolt shaped like a
mushroom and called from its shape " the
mushroom head." When the gun is fired
the pressure of the powder-gas forces the
mushroom head back, compresses the canvas
pad, and squeezing it outwards makes it bear
closely against the interior of the gun, so that
an escape of gas is impossible ; when the
projectile is clear of the gun, and the pressure
is removed, the pad returns to its original
condition by its own elasticity, and the
breech-screw is easily withdrawn. The
effectual closing of the breech so as to
prevent the escape of gas has long been a
problem whose difficulty is only surpassed
by its importance, for it must be remembered
that the powder-gas exerts the same enor
mous pressure upon the breech-piece as it
does upon the projectile ; but that the Klswick
Company have hit upon an efficient method
is sufficiently proved by the fact that the
British service guns are fitted on the same
principle.

The arrangements for firing the gun
appear to be simple, but as a matter of fact



THE MAKING OF BIG GUNS.



231



thcv arc curefullv elaborate, for unless several
levers each lie in a particular way it is im
possible for the needle-hammer to strike the
needle, or for the needle to strike the
primer. The small primer-cartridge, \vhich
by its flash fires the great charge of powder,
is ingeniously constructed so as to prevent
the escape of gas. It is a close-ended tube,
and, the metal being flexible, the cap, which
is inside, is fired by the striker without any
hole being made through the base of the
cartridge. This close cartridge was intro
duced by the Elswick Company. The gun
is fired by the hammer at full cock, which,
moved by a pull upon a lanyard, strikes the
needle, the action of which fires the powder.
In turrets the guns are fired by electricity
by the commander, who, unlike those work
ing the guns, is in full sight of the object of
attack, but field guns are generally fired by
hand.

Now completed, the gun, after an im
pression of its interior has been taken in



gutta-percha, is ready for proof. Guns are
almost continually being proved at a range
which the Klswick Company possesses in
the moorland district of Ridsdale, thirty-
five miles north-west of Newcastle. Machine
guns are tried on the moor adjoining the
late Lord Armstrong s seat at Cragside, near
Rothbury, forty miles from Newcastle, and
experimental firing with big guns is carried
on at a tidal range of four-and-a-half miles
at Silloth, on the west coast. Only the guns
ordered by the British Government go to
their destination unproved. Of course, in
the case of guns fitted to ships-of-war built
at Elswick, special firing tests always con
stitute part of the trial trip to which the ship
is subjected before being duly handed over to
her owners. So, naturally, are guns fitted on
his Majesty s ships before the ships are put in
commission. And it is proof of the gun-
makers accuracy, whether at Elswick, Wool
wich, or elsewhere, that these guns seldom
fail in successfully passing their firing tests.

R. \V. JOHNSON.




I ltolo: Gregory f- Co., Stramt, ll .C.

AFTKK BARBETTE OK H.M.S. CAMPERDOWN, SHOWING 67-TON GUNS AND MACHINE GUNS.



232



HOW MONEY IS COINED.

A VISIT TO THE ROYAL MINT.



IF you stand at the north end of the Tower
Bridge, with your back to Father Thames,
vou will have the ancient Tower of London
on your left hand and the outskirts of St.
Katharine s Docks on the other. In front
of you there rises a block of old-fashioned
buildings, whose gates are guarded night and
day by red-coated sentries. This is the Royal
Mint, where all the money coined in England




THE GOLD MELTING ROOM.

is made. Some of the operations by which
money is coined are shown to privileged
visitors at certain hours. Hut the number of
people admitted at one time is only half a
dozen, and in the course of the year less
than 10,000 visitors enter their names in
the book. For this reason the special photo
graphs which we are privileged to publish
will be welcomed with interest.

Leaving the Tower Hill, with its romantic
associations, behind us, let us cross the
road to the little postern gate, at which
two police sentries are stationed. The
neighbourhood, dingy as it now is, should
be sacred in the eyes of every Englishman,
because it is the oldest part of London.



For centuries the spot upon which we are
now standing was the site of the old
abbey of Eastminster, which at one time
was more famous than its great rival at
Westminster. Until the beginning of the
nineteenth century the minting of money
had been carried on in London at the
Tower ever since the time of the Romans
themselves, but in 1811 the sum of 250,000
was voted for the purpose
of erecting the Royal
Mint, and since that time
various changes have been
made in the buildings to
enable them to cope with
the enormous and in
creasing demand for
coins that comes from
every part of the Empire
year after year.

All this time, we will
suppose, the police officer
has been examining our
credentials. We at length
find o u r s e 1 ve s i n a
spacious courtyard, neatly
laid out with greenery.
In the corners may be
seen the official residences
of the Deputy Master, the
superintendent, the assayer, the chief clerk,
and other officials who are always on the
spot. The imposing structure in the centre
contains the Mint Office, by which all the
work of this curious colon}- of skilful artisans
is regulated. The first thing to be clone-
on the principle of the famous Mrs. Glasse
is to catch your ore. This comes into
the possession of the Mint in the shape of
ingots, which at busy times arrive in vans
two or three times a week. After running the
gauntlet of the sentinels, the vans rattle over
the cobble-stones of the courtyard to the
main entrance. Through this the ingots pass,
and after being weighed they are stored in
the strong-room until they have been assayed.



HOW MONEY IS COIXKD.



233



The gold ingots, which all come from the
Bank of England, weigh 400 ounces apiece,
and there are times when the Mint has a
little stock of 35 tons of gold to go on with.
Silver ingots, on the other hand, weigh about
100 lb. each, and there may be a small matter
of 20 tons in stock at a time. Copper is also
required, but this does not always arrive in
the form of ingots nowadays, but is delivered
by a Birmingham factory in
the form of blank discs, ready
for stamping into bronze
coins, of which the average
production is a ton per day.

Every morning the chief
officials have to decide what
coins are to be made. Some
times the Bank of England
informs the Mint that it is
running short of half-sover
eigns ; at another time there
may be a demand from the



the same weight of metal, but in the form
of finished coins.

His first care is to pass it on to the
melting house. This is a sort of kitchen,
with separate departments for gold and
silver, and a staff of about sixteen men.
A couple of ingots, with some of the
waste gold left after the coins have been
cut from the strips, are dropped into a





MARKING
MACHIXK.



Bank of South Africa for an extra supply
of silver money. All these little points have
to be taken into consideration, and the work
is planned out accordingly. Let us suppose
that sovereigns are to be made on a certain
day. So much gold, with the proper propor
tion of alloy, is weighed out and delivered
to the superintendent, who is responsible for
passing it on from room to room, until he
returns it again to the chief office in precisely
30



ROLLING FILLETS.

blacklcad crucible, which is then lowered
into one of the eight furnaces that stand
in a row. The gold and the copper are
slowly melted until they have the appear
ance of so much dull coloured liquor. At
the end of an hour the red-hot crucible is
lifted by means of tongs, and the molten gold
poured into eight or nine moulds, each of
which produces a bar of the value of about
600. Each of the furnaces is therefore
able to melt its little potful six times in the
course of the day, and when the Mint is
engaged upon this feast of Midas, it is able
to turn out golden bars at the rate of
a quarter of a million sterling every day.
The same course is pursued when boiling
silver, except that the blacklead saucepans
used for this metal hold about 5,000 oz.
apiece. No one could possibly lift such a



Online LibraryHenry HarrisseBritain at work; a pictorial description of our national industries → online text (page 23 of 39)