Chapter 15 - Page 2

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.