Chapter: During the eight months which were employed in the work of
excavation the preparatory works of the casting had been carried
on simultaneously with extreme rapidity.  A stranger arriving at
Stones Hill would have been surprised at the spectacle offered
to his view.

At 600 yards from the well, and circularly arranged around it as
a central point, rose 1,200 reverberating ovens, each six feet
in diameter, and separated from each other by an interval of
three feet.  The circumference occupied by these 1,200 ovens
presented a length of two miles.  Being all constructed on the
same plan, each with its high quadrangular chimney, they
produced a most singular effect.

It will be remembered that on their third meeting the committee
had decided to use cast iron for the Columbiad, and in particular
the white description.  This metal, in fact, is the most
tenacious, the most ductile, and the most malleable, and
consequently suitable for all moulding operations; and when
smelted with pit coal, is of superior quality for all
engineering works requiring great resisting power, such as
cannon, steam boilers, hydraulic presses, and the like.

Cast iron, however, if subjected to only one single fusion,
is rarely sufficiently homogeneous; and it requires a second
fusion completely to refine it by dispossessing it of its last
earthly deposits.  So long before being forwarded to Tampa Town,
the iron ore, molten in the great furnaces of Coldspring, and
brought into contact with coal and silicium heated to a high
temperature, was carburized and transformed into cast iron.
After this first operation, the metal was sent on to Stones Hill.
They had, however, to deal with 136,000,000 pounds of iron, a
quantity far too costly to send by railway.  The cost of
transport would have been double that of material.  It appeared
preferable to freight vessels at New York, and to load them with
the iron in bars.  This, however, required not less than sixty-
eight vessels of 1,000 tons, a veritable fleet, which, quitting
New York on the 3rd of May, on the 10th of the same month ascended
the Bay of Espiritu Santo, and discharged their cargoes, without
dues, in the port at Tampa Town.  Thence the iron was transported
by rail to Stones Hill, and about the middle of January this
enormous mass of metal was delivered at its destination.

It will easily be understood that 1,200 furnaces were not too
many to melt simultaneously these 60,000 tons of iron.  Each of
these furnaces contained nearly 140,000 pounds weight of metal.
They were all built after the model of those which served for
the casting of the Rodman gun; they were trapezoidal in shape,
with a high elliptical arch.  These furnaces, constructed of
fireproof brick, were especially adapted for burning pit coal,
with a flat bottom upon which the iron bars were laid.  This bottom,
inclined at an angle of 25 degrees, allowed the metal to flow into
the receiving troughs; and the 1,200 converging trenches carried
the molten metal down to the central well.

The day following that on which the works of the masonry and
boring had been completed, Barbicane set to work upon the
central mould.  His object now was to raise within the center of
the well, and with a coincident axis, a cylinder 900 feet high,
and nine feet in diameter, which should exactly fill up the
space reserved for the bore of the Columbiad.  This cylinder was
composed of a mixture of clay and sand, with the addition of a
little hay and straw.  The space left between the mould and the
masonry was intended to be filled up by the molten metal, which
would thus form the walls six feet in thickness.  This cylinder,
in order to maintain its equilibrium, had to be bound by iron
bands, and firmly fixed at certain intervals by cross-clamps
fastened into the stone lining; after the castings these would
be buried in the block of metal, leaving no external projection.

This operation was completed on the 8th of July, and the run of
the metal was fixed for the following day.

"This _fete_ of the casting will be a grand ceremony," said J.
T. Maston to his friend Barbicane.

"Undoubtedly," said Barbicane; "but it will not be a public _fete_"

"What! will you not open the gates of the enclosure to all comers?"

"I must be very careful, Maston.  The casting of the Columbiad
is an extremely delicate, not to say a dangerous operation, and
I should prefer its being done privately.  At the discharge of
the projectile, a _fete_ if you like-- till then, no!"

The president was right.  The operation involved unforeseen
dangers, which a great influx of spectators would have hindered
him from averting.  It was necessary to preserve complete
freedom of movement.  No one was admitted within the enclosure
except a delegation of members of the Gun Club, who had made the
voyage to Tampa Town.  Among these was the brisk Bilsby, Tom
Hunter, Colonel Blomsberry, Major Elphinstone, General Morgan,
and the rest of the lot to whom the casting of the Columbiad was
a matter of personal interest.  J. T. Maston became their cicerone.
He omitted no point of detail; he conducted them throughout the
magazines, workshops, through the midst of the engines, and
compelled them to visit the whole 1,200 furnaces one after
the other.  At the end of the twelve-hundredth visit they were
pretty well knocked up.

The casting was to take place at twelve o'clock precisely.
The previous evening each furnace had been charged with 114,000
pounds weight of metal in bars disposed cross-ways to each other,
so as to allow the hot air to circulate freely between them.
At daybreak the 1,200 chimneys vomited their torrents of flame
into the air, and the ground was agitated with dull tremblings.
As many pounds of metal as there were to cast, so many pounds of
coal were there to burn.  Thus there were 68,000 tons of coal
which projected in the face of the sun a thick curtain of smoke.
The heat soon became insupportable within the circle of furnaces,
the rumbling of which resembled the rolling of thunder.  The powerful
ventilators added their continuous blasts and saturated with
oxygen the glowing plates.  The operation, to be successful,
required to be conducted with great rapidity.  On a signal given
by a cannon-shot each furnace was to give vent to the molten
iron and completely to empty itself.  These arrangements made,
foremen and workmen waited the preconcerted moment with an
impatience mingled with a certain amount of emotion.  Not a soul
remained within the enclosure.  Each superintendent took his
post by the aperture of the run.

Barbicane and his colleagues, perched on a neighboring eminence,
assisted at the operation.  In front of them was a piece of
artillery ready to give fire on the signal from the engineer.
Some minutes before midday the first driblets of metal began to
flow; the reservoirs filled little by little; and, by the time
that the whole melting was completely accomplished, it was kept
in abeyance for a few minutes in order to facilitate the
separation of foreign substances.

Twelve o'clock struck!  A gunshot suddenly pealed forth and shot
its flame into the air.  Twelve hundred melting-troughs were
simultaneously opened and twelve hundred fiery serpents crept
toward the central well, unrolling their incandescent curves.
There, down they plunged with a terrific noise into a depth of
900 feet.  It was an exciting and a magnificent spectacle.
The ground trembled, while these molten waves, launching into the
sky their wreaths of smoke, evaporated the moisture of the mould
and hurled it upward through the vent-holes of the stone lining
in the form of dense vapor-clouds.  These artificial clouds
unrolled their thick spirals to a height of 1,000 yards into
the air.  A savage, wandering somewhere beyond the limits of the
horizon, might have believed that some new crater was forming in
the bosom of Florida, although there was neither any eruption,
nor typhoon, nor storm, nor struggle of the elements, nor any of
those terrible phenomena which nature is capable of producing.
No, it was man alone who had produced these reddish vapors,
these gigantic flames worthy of a volcano itself, these
tremendous vibrations resembling the shock of an earthquake,
these reverberations rivaling those of hurricanes and storms;
and it was his hand which precipitated into an abyss, dug by
himself, a whole Niagara of molten metal!

 With the hole complete, it's now time to cast the cannon. Maston wants to hold a big public festival, but Barbicane shoots him down--he doesn't want to risk anything going wrong. When they finally start the massive furnaces required for casting, huge "artificial clouds in thick spirals" are released into the sky.

