THE FÊTE OF THE CASTING.
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 1200 reverberating ovens, each six feet in diameter, and
separated from each other by an interval of three feet. The circumference
occupied by these 1200 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 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 lbs. 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 1000 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 be easily understood that 1200 furnaces were not too many to
melt simultaneously these 60,000 tons of iron. Each of these furnaces
contained nearly 140,000 lbs. 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°, allowed the metal to flow into the
receiving troughs; and the 1200 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 centre of the well, and with a coincident
axis, a cylinder 900 feet high, and 9 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.
Illustration: THE CASTING.
This operation was completed on the 8th of July, and the run of the metal
was fixed for the following day.
"This fête 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 fête."
"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 fête 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
1200 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 12 o'clock precisely. The previous
evening each furnace had been charged with 114,000 lbs. 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 1200 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 neighbouring 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 towards 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 upwards through the vent-holes of the stone
lining in the form of dense vapour-clouds. These artificial clouds
unrolled their thick spirals to a height of 1000 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 vapours, these gigantic flames worthy of a volcano itself,
these tremendous vibrations resembling the shock of an earthquake, these
reverberations rivalling those of hurricanes and storms; and it was his
hand which precipitated into an abyss, dug by himself, a whole Niagara
of molten metal!