Excerpt
from "The aluminium cannonball" (Jules Vernes's
novel "From the Earth to the Moon", 1865)
The
Observatory of Cambridge in its memorable letter had treated the
question from a purely astronomical point of view. The mechanical
part still remained. President Barbicane had, without loss of time,
nominated a working committee of the Gun Club.
The
duty of this committee was to resolve the three grand questions
of the cannon, the projectile, and the powder. It was composed of
four members of great technical knowledge, Barbicane (with a casting
vote in case of equality), General Morgan, Major Elphinstone, and
J. T. Maston, to whom were confided the functions of secretary.
On the 8th of October the committee met at the house of President
Barbicane, 3 Republican Street. The meeting was opened by the president
himself.
"Gentlemen,"
said he, "we have to resolve one of the most important problems
in the whole of the noble science of gunnery. It might appear, perhaps,
the most logical course to devote our first meeting to the discussion
of the engine to be employed.
Nevertheless,
after mature consideration, it has appeared to me that the question
of the projectile must take precedence of that of the cannon, and
that the dimensions of the latter must necessarily depend on those
of the former."
The major : "But what metal do you calculate upon employing?"
"Simply
cast iron," said General Morgan.
"But,"
interrupted the major, "since the weight of a shot is proportionate
to its volume, an iron ball of nine feet in diameter would be of
tremendous weight."
"Yes,
if it were solid, not if it were hollow."
"Hollow?
then it would be a shell?"
"Yes,
a shell," replied Barbicane; "decidedly it must be. A
solid shot of 108 inches would weigh more than 200,000 pounds, a
weight evidently far too great. Still, as we must reserve a certain
stability for our projectile, I propose to give it a weight of 20,000
pounds."
"What,
then, will be the thickness of the sides?" asked the major.
"If
we follow the usual proportion," replied Morgan, "a diameter
of 108 inches would require sides of two feet thickness, or less."
"That would be too much," replied Barbicane; "for
you will observe that the question is not that of a shot intended
to pierce an iron plate; it will suffice to give it sides strong
enough to resist the pressure of the gas. The problem, therefore,
is this — What thickness ought a cast-iron shell to have in
order not to weight more than 20,000 pounds? Our clever secretary
will soon enlighten us upon this point."
"Nothing easier." replied the worthy secretary of the
committee; and, rapidly tracing a few algebraical formulae upon
paper, among which n2 and x2 frequently appeared, he presently said:
"The sides will require a thickness of less than two inches."
"Will that be enough?" asked the major doubtfully.
"Clearly not!" replied the president.
"What is to be done, then?" said Elphinstone, with a puzzled
air.
"Employ another metal instead of iron."
"Copper?" said Morgan.
"No! that would be too heavy. I have better than that to offer."
"What then?" asked the major.
"Aluminium!" replied Barbicane.
"Aluminium?" cried his three colleagues in chorus.
"Unquestionably, my friends. This valuable metal possesses
the whiteness of silver, the indestructibility of gold, the tenacity
of iron, the fusibility of copper, the lightness of glass. It is
easily wrought, is very widely distributed, forming the base of
most of the rocks, is three times lighter than iron, and seems to
have been created for the express purpose of furnishing us with
the material for our projectile."
"But, my dear president," said the major, "is not
the cost price of aluminium extremely high?"
"It was so at its first discovery, but it has fallen now to
nine dollars a pound."
"But still, nine dollars a pound!" replied the major,
who was not willing readily to give in; "even that is an enormous
price."
"Undoubtedly, my dear major; but not beyond our reach."
"What will the projectile weigh then?" asked Morgan.
"Here is the result of my calculations," replied Barbicane.
"A shot of 108 inches in diameter, and twelve inches in thickness,
would weigh, in cast-iron, 67,440 pounds; cast in aluminium, its
weight will be reduced to 19,250 pounds."
"Capital!" cried the major; "but do you know that,
at nine dollars a pound, this projectile will cost…"
"One hundred and seventy-three thousand and fifty dollars ($173,050).
I know it quite well. But fear not, my friends; the money will not
be wanting for our enterprise. I will answer for it. Now what say
you to aluminium, gentlemen?"
"Adopted!" replied the three members of the committee.
So ended the first meeting. The question of the projectile was definitely
settled.
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