Maston. "For my part, I ask for a cannon
half a mile long at least!"
"Half a mile!" cried the major and the general.
"Yes, half a mile, and that will be half too short."
"Come, Maston," answered Morgan, "you exaggerate."
"No, I do not," said the irate secretary; "and I really do not know why
you tax me with exaggeration."
"Because you go too far."
"You must know, sir," answered J.T. Maston, looking dignified, "that an
artilleryman is like a cannon-ball, he can never go too far."
The debate was getting personal, but the president interfered.
"Be calm, my friends, and let us reason it out. We evidently want a gun
of great range, as the length of the engine will increase the detention
of gas accumulated behind the projectile, but it is useless to overstep
certain limits."
"Perfectly," said the major.
"What are the usual rules in such a case? Ordinarily the length of a
cannon is twenty or twenty-five times the diameter of the projectile,
and it weighs 235 to 240 times its weight."
"It is not enough," cried J.T. Maston with impetuosity.
"I agree to that, my worthy friend, and in fact by keeping that
proportion for a projectile nine feet wide, weighing 30,000 lbs., the
engine would only have a length of 225 feet and a weight of 7,200,000
lbs."
"That is ridiculous," resumed J.T. Maston. "You might as well take a
pistol."
"I think so too," answered Barbicane; "that is why I propose to
quadruple that length, and to construct a cannon 900 feet long."
The general and the major made some objections, but, nevertheless, this
proposition, strongly supported by the secretary, was definitely
adopted.
"Now," said Elphinstone, "what thickness must we give its sides?"
"A thickness of six feet," answered Barbicane.
"You do not think of raising such a mass upon a gun-carriage?" asked the
major.
"That would be superb, however! said J.T. Maston.
"But impracticable," answered Barbicane. "No, I think of casting this
engine in the ground itself, binding it up with wrought-iron hoops, and
then surrounding it with a thick mass of stone and cement masonry. When
it is cast it must be bored with great precision so as to prevent
windage, so there will be no loss of gas, and all the expansive force of
the powder will be employed in the propulsion."
"Hurrah! hurrah!" said Maston, "we have our cannon."
"Not yet," answered Barbicane, calming his impatient friend with his
hand.
"Why not?"
"Because we have not discussed its form. Shall it be a cannon, howitzer,
or a mortar?"
"A cannon," replied Morgan.
"A howitzer," said the major.
"A mortar," exclaimed J.T. Maston.
A fresh discussion was pending, each taking the part of his favourite
weapon, when the president stopped it short.
"My friends," said he, "I will soon make you agree. Our Columbiad will
be a mixture of all three. It will be a cannon, because the
powder-magazine will have the same diameter as the chamber. It will be a
howitzer, because it will hurl an obus. Lastly, it will be a mortar,
because it will be pointed at an angle of 90°, and that without any
chance of recoil; unalterably fixed to the ground, it will communicate
to the projectile all the power of impulsion accumulated in its body."
"Adopted, adopted," answered the members of the committee.
"One question," said Elphinstone, "and will this canobusomortar be
rifled?"
"No," answered Barbicane. "No, we must have an enormous initial speed,
and you know very well that a shot leaves a rifle less rapidly than a
smooth-bore."
"True," answered the major.
"Well, we have it this time," repeated J.T. Maston.
"Not quite yet," replied the president.
"Why not?"
"Because we do not yet know of what metal it will be made."
"Let us decide that without delay."
"I was going to propose it to you."
The four members of the committee each swallowed a dozen sandwiches,
followed by a cup of tea, and the debate recommenced.
"Our cannon," said Barbicane, "must be possessed of great tenacity,
great hardness; it must be infusible by heat, indissoluble, and
inoxydable by the corrosive action of acids."
"There is no doubt about that," answered the major, "and as we shall
have to employ a considerable quantity of metal we shall not have much
choice."
"Well, then," said Morgan, "I propose for the fabrication of the
Columbiad the best alloy hitherto known—that is to say, 100 parts of
copper, 12 of tin, and 6 of brass."
"My friends," answered the president, "I agree that this composition has
given excellent results; but in bulk it would be too dear and very hard
to work. I therefore think we must adopt an excellent material, but
cheap, such as cast-iron. Is not that your opinion, major?"
"Quite," answered Elphinstone.
"In fact," resumed Barbicane, "cast-iron costs ten times less than
bronze; it is easily melted, it is readily run into sand moulds, and is
rapidly manipulated; it is, therefore, an economy of money and time.
Besides, that material is excellent, and I remember that during the war
at the siege of Atlanta cast-iron cannon fired a thousand shots each
every twenty minutes without being damaged by it."
"Yet cast-iron is very brittle," answered Morgan.
"Yes, but it possesses resistance too. Besides, we shall not let it
explode, I can answer for that."
"It is possible to explode and yet be honest," replied J.T. Maston
sententiously.
"Evidently," answered Barbicane. "I am, therefore, going to beg our
worthy secretary to calculate the weight of a cast-iron cannon 900 feet
long, with an inner diameter of nine feet, and sides six feet thick."
"At once," answered J.T. Maston, and, as he had done the day before, he
made his calculations with marvellous facility, and said at the end of a
minute—
"This cannon will weigh 68,040 tons."
"And how much will that cost at two cents a pound?"
"Two million five hundred and ten thousand seven hundred and one
dollars."
J.T. Maston, the major, and the general looked at Barbicane anxiously.
"Well, gentlemen," said the president, "I can only repeat what I said to
you yesterday, don't be uneasy; we shall not want for money."
Upon this assurance of its president the committee broke up, after
having fixed a third meeting for the next evening.
*
The question of powder still remained to be settled. The public awaited
this last decision with anxiety. The size of the projectile and length
of the cannon being given, what would be the quantity of powder
necessary to produce the impulsion? This terrible agent, of which,
however, man has made himself master, was destined to play a part in
unusual proportions.
It is generally known and often asserted that gunpowder was invented in
the fourteenth century by the monk Schwartz, who paid for his great
discovery with his life. But it is nearly proved now that this story
must be ranked among the legends of the Middle Ages. Gunpowder was
invented by no one; it is a direct product of Greek fire, composed, like
it, of sulphur and saltpetre; only since that epoch these mixtures;
which were only dissolving, have been transformed into detonating
mixtures.
But if learned men know perfectly the false history of gunpowder, few
people are aware of its mechanical power. Now this is necessary to be
known in order to understand the importance of the question submitted to
the committee.
Thus a litre of gunpowder weighs about 2 lbs.; it produces, by burning,
about 400 litres of gas; this gas, liberated, and under the action of a
temperature of 2,400°, occupies the space of 4,000 litres.
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