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1THE HYMN OF THE CANNON-BALL The Observatory of Cambridge in its memorable letter had treated the question from a purely
2astronomical point of view. The mechanical part still remained. President Barbicane had, without loss of time, nominated
3a working committee of the Gun Club. The duty of this committee was to resolve the three grand questions of the cannon,
4the projectile, and the powder. It was composed of four members of great technical knowledge, Barbicane (with a casting
5vote in case of equality), General Morgan, Major Elphinstone, and J. T. Maston, to whom were confided the functions of
6secretary. On the 8th of October the committee met at the house of President Barbicane, 3 Republican Street. The meeting
7was opened by the president himself. "Gentlemen," said he, "we have to resolve one of the most important problems in the
8whole of the noble science of gunnery. It might appear, perhaps, the most logical course to devote our first meeting to
9the discussion of the engine to be employed. Nevertheless, after mature consideration, it has appeared to me that the
10question of the projectile must take precedence of that of the cannon, and that the dimensions of the latter must
11necessarily depend on those of the former." "Suffer me to say a word," here broke in J. T. Maston. Permission having
12been granted, "Gentlemen," said he with an inspired accent, "our president is right in placing the question of the
13projectile above all others. The ball we are about to discharge at the moon is our ambassador to her, and I wish to
14consider it from a moral point of view. The cannon-ball, gentlemen, to my mind, is the most magnificent manifestation of
15human power. If Providence has created the stars and the planets, man has called the cannon-ball into existence. Let
16Providence claim the swiftness of electricity and of light, of the stars, the comets, and the planets, of wind and
17sound--we claim to have invented the swiftness of the cannon-ball, a hundred times superior to that of the swiftest
18horses or railway train. How glorious will be the moment when, infinitely exceeding all hitherto attained velocities, we
19shall launch our new projectile with the rapidity of seven miles a second! Shall it not, gentlemen--shall it not be
20received up there with the honors due to a terrestrial ambassador?" Overcome with emotion the orator sat down and
21applied himself to a huge plate of sandwiches before him. "And now," said Barbicane, "let us quit the domain of poetry
22and come direct to the question." "By all means," replied the members, each with his mouth full of sandwich. "The
23problem before us," continued the president, "is how to communicate to a projectile a velocity of 12,000 yards per
24second. Let us at present examine the velocities hitherto attained. General Morgan will be able to enlighten us on this
25point." "And the more easily," replied the general, "that during the war I was a member of the committee of experiments.
26I may say, then, that the 100-pounder Dahlgrens, which carried a distance of 5,000 yards, impressed upon their
27projectile an initial velocity of 500 yards a second. The Rodman Columbiad threw a shot weighing half a ton a distance
28of six miles, with a velocity of 800 yards per second--a result which Armstrong and Palisser have never obtained in
29England." "This," replied Barbicane, "is, I believe, the maximum velocity ever attained?" "It is so," replied the
30general. "Ah!" groaned J. T. Maston, "if my mortar had not burst--" "Yes," quietly replied Barbicane, "but it did burst.
31We must take, then, for our starting point, this velocity of 800 yards. We must increase it twenty-fold. Now, reserving
32for another discussion the means of producing this velocity, I will call your attention to the dimensions which it will
33be proper to assign to the shot. You understand that we have nothing to do here with projectiles weighing at most but
34half a ton." "Why not?" demanded the major. "Because the shot," quickly replied J. T. Maston, "must be big enough to
35attract the attention of the inhabitants of the moon, if there are any?" "Yes," replied Barbicane, "and for another
36reason more important still." "What mean you?" asked the major. "I mean that it is not enough to discharge a projectile,
37and then take no further notice of it; we must follow it throughout its course, up to the moment when it shall reach its
38goal." "What?" shouted the general and the major in great surprise. "Undoubtedly," replied Barbicane composedly, "or our
39experiment would produce no result." "But then," replied the major, "you will have to give this projectile enormous
40dimensions." "No! Be so good as to listen. You know that optical instruments have acquired great perfection; with
41certain instruments we have succeeded in obtaining enlargements of 6,000 times and reducing the moon to within forty
42miles' distance. Now, at this distance, any objects sixty feet square would be perfectly visible. "If, then, the
43penetrative power of telescopes has not been further increased, it is because that power detracts from their light; and
44the moon, which is but a reflecting mirror, does not give back sufficient light to enable us to perceive objects of
45lesser magnitude." "Well, then, what do you propose to do?" asked the general. "Would you give your projectile a
46diameter of sixty feet?" "Not so." "Do you intend, then, to increase the luminous power of the moon?" "Exactly so. If I
47can succeed in diminishing the density of the atmosphere through which the moon's light has to travel I shall have
48rendered her light more intense. To effect that object it will be enough to establish a telescope on some elevated
49mountain. That is what we will do." "I give it up," answered the major. "You have such a way of simplifying things. And
50what enlargement do you expect to obtain in this way?" "One of 48,000 times, which should bring the moon within an
51apparent distance of five miles; and, in order to be visible, objects need not have a diameter of more than nine feet."
52"So, then," cried J. T. Maston, "our projectile need not be more than nine feet in diameter." "Let me observe, however,"
53interrupted Major Elphinstone, "this will involve a weight such as--" "My dear major," replied Barbicane, "before
54discussing its weight permit me to enumerate some of the marvels which our ancestors have achieved in this respect. I
55don't mean to pretend that the science of gunnery has not advanced, but it is as well to bear in mind that during the
56middle ages they obtained results more surprising, I will venture to say, than ours. For instance, during the siege of
57Constantinople by Mahomet II., in 1453, stone shot of 1,900 pounds weight were employed. At Malta, in the time of the
58knights, there was a gun of the fortress of St. Elmo which threw a projectile weighing 2,500 pounds. And, now, what is
59the extent of what we have seen ourselves? Armstrong guns discharging shot of 500 pounds, and the Rodman guns
60projectiles of half a ton! It seems, then, that if projectiles have gained in range, they have lost far more in weight.
61Now, if we turn our efforts in that direction, we ought to arrive, with the progress on science, at ten times the weight
62of the shot of Mahomet II. and the Knights of Malta." "Clearly," replied the major; "but what metal do you calculate
63upon employing?" "Simply cast iron," said General Morgan. "But," interrupted the major, "since the weight of a shot is
64proportionate to its volume, an iron ball of nine feet in diameter would be of tremendous weight." "Yes, if it were
65solid, not if it were hollow." "Hollow? then it would be a shell?" "Yes, a shell," replied Barbicane; "decidely it must
66be. A solid shot of 108 inches would weigh more than 200,000 pounds, a weight evidently far too great. Still, as we must
67reserve a certain stability for our projectile, I propose to give it a weight of 20,000 pounds." "What, then, will be
68the thickness of the sides?" asked the major. "If we follow the usual proportion," replied Morgan, "a diameter of 108
69inches would require sides of two feet thickness, or less." "That would be too much," replied Barbicane; "for you will
70observe that the question is not that of a shot intended to pierce an iron plate; it will suffice to give it sides
71strong enough to resist the pressure of the gas. The problem, therefore, is this--What thickness ought a cast-iron shell
72to have in order not to weight more than 20,000 pounds? Our clever secretary will soon enlighten us upon this point."
73"Nothing easier." replied the worthy secretary of the committee; and, rapidly tracing a few algebraical formulae upon
74paper, among which n2 and x2 frequently appeared, he presently said: "The sides will require a thickness of less than
75two inches." "Will that be enough?" asked the major doubtfully. "Clearly not!" replied the president.
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