by Anthology
"Then," resumed Barbicane, "a speed of 800 yards is the maximum obtained at present."
"Yes," answered Morgan.
"I might add, however," replied J.T. Maston, "that if my mortar had not been blown up--"
"Yes, but it was blown up," replied Barbicane with a benevolent gesture. "We must take the speed of 800 yards for a starting point. We must keep till another meeting the discussion of the means used to produce this speed; allow me to call your attention to the dimensions which our projectile must have. Of course it must be something very different to one of half a ton weight."
"Why?" asked the major.
"Because," quickly answered J.T. Maston, "it must be large enough to attract the attention of the inhabitants of the moon, supposing there are any."
"Yes," answered Barbicane, "and for another reason still more important."
"What do you mean, Barbicane?" asked the major.
"I mean that it is not enough to send up a projectile and then to think no more about it; we must follow it in its transit."
"What?" said the general, slightly surprised at the proposition.
"Certainly," replied Barbicane, like a man who knew what he was saying, "or our experiment will be without result."
"But then," replied the major, "you will have to give the projectile enormous dimensions."
"No. Please grant me your attention. You know that optical instruments have acquired great perfection; certain telescopes increase objects six thousand, and bring the moon to within a distance of forty miles. Now at that distance objects sixty feet square are perfectly visible. The power of penetration of the telescope has not been increased, because that power is only exercised to the detriment of their clearness, and the moon, which is only a reflecting mirror, does not send a light intense enough for the telescopes to increase objects beyond that limit."
"Very well, then, what do you mean to do?" asked the general. "Do you intend giving a diameter of sixty feet to your projectile?"
"No."
"You are not going to take upon yourself the task of making the moon more luminous?"
"I am, though."
"That's rather strong!" exclaimed Maston.
"Yes, but simple," answered Barbicane. "If I succeed in lessening the density of the atmosphere which the moon's light traverses, shall I not render that light more intense?"
"Evidently."
"In order to obtain that result I shall only have to establish my telescope upon some high mountain. We can do that."
"I give in," answered the major; "you have such a way of simplifying things! What enlargement do you hope to obtain thus?"
"One of 48,000 times, which will bring the moon within five miles only, and objects will only need a diameter of nine feet."
"Perfect!" exclaimed J.T. Maston; "then our projectile will have a diameter of nine feet?"
"Precisely."
"Allow me to inform you, however," returned Major Elphinstone, "that its weight will still be--"
"Oh, major!" answered Barbicane, "before discussing its weight allow me to tell you that our forefathers did marvels in that way. Far be it from me to pretend that ballistics have not progressed, but it is well to know that in the Middle Ages surprising results were obtained, I dare affirm, even more surprising than ours."
"Justify your statement," exclaimed J.T. Maston.
"Nothing is easier," answered Barbicane; "I can give you some examples. At the siege of Constantinople by Mahomet II., in 1453, they hurled stone bullets that weighed 1,900 lbs.; at Malta, in the time of its knights, a certain cannon of Fort Saint Elme hurled projectiles weighing 2,500 lbs. According to a French historian, under Louis XI. a mortar hurled a bomb of 500 lbs. only; but that bomb, fired at the Bastille, a place where mad men imprisoned wise ones, fell at Charenton, where wise men imprison mad ones."
"Very well," said J.T. Maston.
"Since, what have we seen, after all? The Armstrong cannons hurl projectiles of 500 lbs., and the Rodman Columbiads projectiles of half a ton! It seems, then, that if projectiles have increased in range they have lost in weight. Now, if we turn our efforts in that direction, we must succeed with the progress of the science in doubling the weight of the projectiles of Mahomet II. and the Knights of Malta."
"That is evident," answered the major; "but what metal do you intend to employ for your own projectile?"
"Simply cast-iron," said General Morgan.
"Cast-iron!" exclaimed J.T. Maston disdainfully, "that's very common for a bullet destined to go to the moon."
"Do not let us exaggerate, my honourable friend," answered Morgan; "cast-iron will be sufficient."
"Then," replied Major Elphinstone, "as the weight of the projectile is in proportion to its volume, a cast-iron bullet, measuring nine feet in diameter, will still be frightfully heavy."
"Yes, if it be solid, but not if it be hollow," said Barbicane.
"Hollow!--then it will be an obus?"
"In which we can put despatches," replied J.T. Maston, "and specimens of our terrestrial productions."
"Yes, an obus," answered Barbicane; "that is what it must be; a solid bullet of 108 inches would weigh more than 200,000 lbs., a weight evidently too great; however, as it is necessary to give the projectile a certain stability, I propose to give it a weight of 20,000 lbs."
"What will be the thickness of the metal?" asked the major.
"If we follow the usual proportions," replied Morgan, "a diameter of 800 inches demands sides two feet thick at least."
"That would be much too thick," answered Barbicane; "we do not want a projectile to pierce armour-plate; it only needs sides strong enough to resist the pressure of the powder-gas. This, therefore, is the problem:--What thickness ought an iron obus to have in order to weigh only 20,000 lbs.? Our clever calculator, Mr. Maston, will tell us at once."
"Nothing is easier," replied the honourable secretary.
So saying, he traced some algebraical signs on the paper, amongst which n^2 and x^2 frequently appeared. He even seemed to extract from them a certain cubic root, and said--
"The sides must be hardly two inches thick."
"Will that be sufficient?" asked the major doubtfully.
"No," answered the president, "certainly not."
"Then what must be done?" resumed Elphinstone, looking puzzled.
"We must use another metal instead of cast-iron."
"Brass?" suggested Morgan.
"No; that is too heavy too, and I have something better than that to propose."
"What?" asked the major.
"Aluminium," answered Barbicane.
"Aluminium!" cried all the three colleagues of the president.
"Certainly, my friends. You know that an illustrious French chemist, Henry St. Claire Deville, succeeded in 1854 in obtaining aluminium in a compact mass. This precious 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, and is very widely distributed in nature, as aluminium forms the basis of most rocks; it is three times lighter than iron, and seems to have been created expressly to furnish us with the material for our projectile!"
"Hurrah for aluminium!" cried the secretary, always very noisy in his moments of enthusiasm.
"But, my dear president," said the major, "is not aluminium quoted exceedingly high?"
"It was so," answered Barbicane; "when first discovered a pound of aluminium cost 260 to 280 dollars; then it fell to twenty-seven dollars, and now it is worth nine dollars."
"But nine dollars a pound," replied the major, who did not easily give in; "that is still an enormous price."
"Doubtless, my dear major; but not out of reach."
"What will the projectile weigh, then?" asked Morgan.
"Here is the result of my calculations," answered Barbicane. "A projectile of 108 inches in diameter and 12 inches thick would weigh, if it were made of cast-iron, 67,440 lbs.; cast in aluminium it would be reduce
d to 19,250 lbs."
"Perfect!" cried Maston; "that suits our programme capitally."
"Yes," replied the major; "but do you not know that at nine dollars a pound the projectile would cost--"
"One hundred seventy-three thousand and fifty dollars. Yes, I know that; but fear nothing, my friends; money for our enterprise will not be wanting, I answer for that."
"It will be showered upon us," replied J.T. Maston.
"Well, what do you say to aluminium?" asked the president.
"Adopted," answered the three members of the committee.
"As to the form of the projectile," resumed Barbicane, "it is of little consequence, since, once the atmosphere cleared, it will find itself in empty space; I therefore propose a round ball, which will turn on itself, if it so pleases."
Thus ended the first committee meeting. The question of the projectile was definitely resolved upon, and J.T. Maston was delighted with the idea of sending an aluminium bullet to the Selenites, "as it will give them no end of an idea of the inhabitants of the earth!"
CHAPTER VIII.
HISTORY OF THE CANNON.
The resolutions passed at this meeting produced a great effect outside. Some timid people grew alarmed at the idea of a projectile weighing 20,000 lbs. hurled into space. People asked what cannon could ever transmit an initial speed sufficient for such a mass. The report of the second meeting was destined to answer these questions victoriously.
The next evening the four members of the Gun Club sat down before fresh mountains of sandwiches and a veritable ocean of tea. The debate then began.
"My dear colleagues," said Barbicane, "we are going to occupy ourselves with the construction of the engine, its length, form, composition, and weight. It is probable that we shall have to give it gigantic dimensions, but, however great our difficulties might be, our industrial genius will easily overcome them. Will you please listen to me and spare objections for the present? I do not fear them."
An approving murmur greeted this declaration.
"We must not forget," resumed Barbicane, "to what point our yesterday's debate brought us; the problem is now the following: how to give an initial speed of 12,000 yards a second to a shot 108 inches in diameter weighing 20,000 lbs.
"That is the problem indeed," answered Major Elphinstone.
"When a projectile is hurled into space," resumed Barbicane, "what happens? It is acted upon by three independent forces, the resistance of the medium, the attraction of the earth, and the force of impulsion with which it is animated. Let us examine these three forces. The resistance of the medium--that is to say, the resistance of the air--is of little importance. In fact, the terrestrial atmosphere is only forty miles deep. With a rapidity of 12,000 yards the projectile will cross that in five seconds, and this time will be short enough to make the resistance of the medium insignificant. Let us now pass to the attraction of the earth--that is to say, to the weight of the projectile. We know that that weight diminishes in an inverse ratio to the square of distances--in fact, this is what physics teach us: when a body left to itself falls on the surface of the earth, it falls 15 feet in the first second, and if the same body had to fall 257,542 miles--that is to say, the distance between the earth and the moon--its fall would be reduced to half a line in the first second. That is almost equivalent to immobility. The question is, therefore, how progressively to overcome this law of gravitation. How shall we do it? By the force of impulsion?"
"That is the difficulty," answered the major.
"That is it indeed," replied the president. "But we shall triumph over it, for this force of impulsion we want depends on the length of the engine and the quantity of powder employed, the one only being limited by the resistance of the other. Let us occupy ourselves, therefore, to-day with the dimensions to be given to the cannon. It is quite understood that we can make it, as large as we like, seeing it will not have to be moved."
"All that is evident," replied the general.
"Until now," said Barbicane, "the longest cannon, our enormous Columbiads, have not been more than twenty-five feet long; we shall therefore astonish many people by the dimensions we shall have to adopt."
"Certainly," exclaimed J.T. 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.
&nbs
p; "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."