The Hymn Of The Cannon-ball

: From The Earth To The Moon

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."



"Suffer me to say a word," here broke in J. T. Maston.

Permission having been granted, "Gentlemen," said he with an

inspired accent, "our president is right in placing the question

of the projectile above all others. The ball we are about to

discharge at the moon is our ambassador to her, and I wish to

consider it from a moral point of view. The cannon-ball,

gentlemen, to my mind, is the most magnificent manifestation of

human power. If Providence has created the stars and the planets,

man has called the cannon-ball into existence. Let Providence

claim the swiftness of electricity and of light, of the stars,

the comets, and the planets, of wind and sound-- we claim to

have invented the swiftness of the cannon-ball, a hundred times

superior to that of the swiftest horses or railway train.

How glorious will be the moment when, infinitely exceeding all

hitherto attained velocities, we shall launch our new projectile

with the rapidity of seven miles a second! Shall it not,

gentlemen-- shall it not be received up there with the honors

due to a terrestrial ambassador?"



Overcome with emotion the orator sat down and applied himself to

a huge plate of sandwiches before him.



"And now," said Barbicane, "let us quit the domain of poetry and

come direct to the question."



"By all means," replied the members, each with his mouth full

of sandwich.



"The problem before us," continued the president, "is how to

communicate to a projectile a velocity of 12,000 yards per second.

Let us at present examine the velocities hitherto attained.

General Morgan will be able to enlighten us on this point."



"And the more easily," replied the general, "that during the war

I was a member of the committee of experiments. I may say,

then, that the 100-pounder Dahlgrens, which carried a distance

of 5,000 yards, impressed upon their projectile an initial

velocity of 500 yards a second. The Rodman Columbiad threw a

shot weighing half a ton a distance of six miles, with a

velocity of 800 yards per second-- a result which Armstrong and

Palisser have never obtained in England."



"This," replied Barbicane, "is, I believe, the maximum velocity

ever attained?"



"It is so," replied the general.



"Ah!" groaned J. T. Maston, "if my mortar had not burst----"



"Yes," quietly replied Barbicane, "but it did burst. We must

take, then, for our starting point, this velocity of 800 yards.

We must increase it twenty-fold. Now, reserving for another

discussion the means of producing this velocity, I will call

your attention to the dimensions which it will be proper to

assign to the shot. You understand that we have nothing to do

here with projectiles weighing at most but half a ton."



"Why not?" demanded the major.



"Because the shot," quickly replied J. T. Maston, "must be big

enough to attract the attention of the inhabitants of the moon,

if there are any?"



"Yes," replied Barbicane, "and for another reason more important still."



"What mean you?" asked the major.



"I mean that it is not enough to discharge a projectile, and

then take no further notice of it; we must follow it throughout

its course, up to the moment when it shall reach its goal."



"What?" shouted the general and the major in great surprise.



"Undoubtedly," replied Barbicane composedly, "or our experiment

would produce no result."



"But then," replied the major, "you will have to give this

projectile enormous dimensions."



"No! Be so good as to listen. You know that optical

instruments have acquired great perfection; with certain

instruments we have succeeded in obtaining enlargements of 6,000

times and reducing the moon to within forty miles' distance.

Now, at this distance, any objects sixty feet square would be

perfectly visible.



"If, then, the penetrative power of telescopes has not been

further increased, it is because that power detracts from their

light; and the moon, which is but a reflecting mirror, does not

give back sufficient light to enable us to perceive objects of

lesser magnitude."



"Well, then, what do you propose to do?" asked the general.

"Would you give your projectile a diameter of sixty feet?"



"Not so."



"Do you intend, then, to increase the luminous power of the moon?"



"Exactly so. If I can succeed in diminishing the density of the

atmosphere through which the moon's light has to travel I shall

have rendered her light more intense. To effect that object it

will be enough to establish a telescope on some elevated mountain.

That is what we will do."



"I give it up," answered the major. "You have such a way of

simplifying things. And what enlargement do you expect to

obtain in this way?"



"One of 48,000 times, which should bring the moon within an

apparent distance of five miles; and, in order to be visible,

objects need not have a diameter of more than nine feet."



"So, then," cried J. T. Maston, "our projectile need not be more

than nine feet in diameter."



"Let me observe, however," interrupted Major Elphinstone, "this

will involve a weight such as----"



"My dear major," replied Barbicane, "before discussing its

weight permit me to enumerate some of the marvels which our

ancestors have achieved in this respect. I don't mean to

pretend that the science of gunnery has not advanced, but it

is as well to bear in mind that during the middle ages they

obtained results more surprising, I will venture to say, than ours.

For instance, during the siege of Constantinople by Mahomet II.,

in 1453, stone shot of 1,900 pounds weight were employed. At Malta,

in the time of the knights, there was a gun of the fortress of St.

Elmo which threw a projectile weighing 2,500 pounds. And, now,

what is the extent of what we have seen ourselves? Armstrong guns

discharging shot of 500 pounds, and the Rodman guns projectiles

of half a ton! It seems, then, that if projectiles have gained

in range, they have lost far more in weight. Now, if we turn our

efforts in that direction, we ought to arrive, with the progress

on science, at ten times the weight of the shot of Mahomet II.

and the Knights of Malta."



"Clearly," replied 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; "decidely 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 n^2 and x^2 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.



"Aluminum!" replied Barbicane.



"Aluminum?" 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 aluminum 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

aluminum, 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 aluminum, gentlemen?"



"Adopted!" replied the three members of the committee. So ended

the first meeting. The question of the projectile was

definitely settled.