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  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 weighing20,000 lbs. hurled into space. People asked what cannon could evertransmit an initial speed sufficient for such a mass. The report of thesecond meeting was destined to answer these questions victoriously.

  The next evening the four members of the Gun Club sat down before freshmountains of sandwiches and a veritable ocean of tea. The debate thenbegan.

  "My dear colleagues," said Barbicane, "we are going to occupy ourselveswith the construction of the engine, its length, form, composition, andweight. It is probable that we shall have to give it giganticdimensions, but, however great our difficulties might be, our industrialgenius will easily overcome them. Will you please listen to me andspare 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'sdebate brought us; the problem is now the following: how to give aninitial speed of 12,000 yards a second to a shot 108 inches in diameterweighing 20,000 lbs.

  "That is the problem indeed," answered Major Elphinstone.

  "When a projectile is hurled into space," resumed Barbicane, "whathappens? It is acted upon by three independent forces, the resistance ofthe medium, the attraction of the earth, and the force of impulsion withwhich it is animated. Let us examine these three forces. The resistanceof the medium--that is to say, the resistance of the air--is of littleimportance. In fact, the terrestrial atmosphere is only forty milesdeep. With a rapidity of 12,000 yards the projectile will cross that infive seconds, and this time will be short enough to make the resistanceof the medium insignificant. Let us now pass to the attraction of theearth--that is to say, to the weight of the projectile. We know thatthat weight diminishes in an inverse ratio to the square ofdistances--in fact, this is what physics teach us: when a body left toitself falls on the surface of the earth, it falls 15 feet in the firstsecond, 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 reducedto half a line in the first second. That is almost equivalent toimmobility. The question is, therefore, how progressively to overcomethis 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 overit, for this force of impulsion we want depends on the length of theengine and the quantity of powder employed, the one only being limitedby the resistance of the other. Let us occupy ourselves, therefore,to-day with the dimensions to be given to the cannon. It is quiteunderstood that we can make it, as large as we like, seeing it will nothave to be moved."

  "All that is evident," replied the general.

  "Until now," said Barbicane, "the longest cannon, our enormousColumbiads, have not been more than twenty-five feet long; we shalltherefore astonish many people by the dimensions we shall have toadopt."

  "Certainly," exclaimed J.T. Maston. "For my part, I ask for a cannonhalf 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 whyyou tax me with exaggeration."

  "Because you go too far."

  "You must know, sir," answered J.T. Maston, looking dignified, "that anartilleryman 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 gunof great range, as the length of the engine will increase the detentionof gas accumulated behind the projectile, but it is useless to overstepcertain limits."

  "Perfectly," said the major.

  "What are the usual rules in such a case? Ordinarily the length of acannon 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 thatproportion for a projectile nine feet wide, weighing 30,000 lbs., theengine would only have a length of 225 feet and a weight of 7,200,000lbs."

  "That is ridiculous," resumed J.T. Maston. "You might as well take apistol."

  "I think so too," answered Barbicane; "that is why I propose toquadruple that length, and to construct a cannon 900 feet long."

  The general and the major made some objections, but, nevertheless, thisproposition, strongly supported by the secretary, was definitelyadopted.

  "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 themajor.

  "That would be superb, however! said J.T. Maston.

  "But impracticable," answered Barbicane. "No, I think of casting thisengine in the ground itself, binding it up with wrought-iron hoops, andthen surrounding it with a thick mass of stone and cement masonry. Whenit is cast it must be bored with great precision so as to preventwindage, so there will be no loss of gas, and all the expansive force ofthe powder will be employed in the propulsion."

  "Hurrah! hurrah!" said Maston, "we have our cannon."

  "Not yet," answered Barbicane, calming his impatient friend with hishand.

  "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 favouriteweapon, when the president stopped it short.

  "My friends," said he, "I will soon make you agree. Our Columbiad willbe a mixture of all three. It will be a cannon, because thepowder-magazine will have the same diameter as the chamber. It will be ahowitzer, because it will hurl an obus. Lastly, it will be a mortar,because it will be pointed at an angle of 90 deg., and that without anychance of recoil; unalterably fixed to the ground, it will communicateto 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_ berifled?"

  "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 asmooth-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, andinoxydable by the corrosive action of acids."

  "There is no doubt about that," answered the major, "and as we shallhave to employ a considerable quantity of metal we shall not have muchchoice."

  "Well, then," said Morgan, "I propose for the fabrication of theColumbiad the best alloy hitherto known--that is to say, 100 parts ofcopper, 12 of tin, and 6 of brass."

  "My friends," answered the president, "I agree that this composition hasgiven excellent results; but in bulk it would be too dear and very hardto work. I therefore think we must adopt an excellent material, butcheap, such as cast-iron. Is not that your opinion, major?"

  "Quite," answered Elphinstone.

&n
bsp; "In fact," resumed Barbicane, "cast-iron costs ten times less thanbronze; it is easily melted, it is readily run into sand moulds, and israpidly manipulated; it is, therefore, an economy of money and time.Besides, that material is excellent, and I remember that during the warat the siege of Atlanta cast-iron cannon fired a thousand shots eachevery 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 itexplode, I can answer for that."

  "It is possible to explode and yet be honest," replied J.T. Mastonsententiously.

  "Evidently," answered Barbicane. "I am, therefore, going to beg ourworthy secretary to calculate the weight of a cast-iron cannon 900 feetlong, 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, hemade his calculations with marvellous facility, and said at the end of aminute--

  "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 onedollars."

  J.T. Maston, the major, and the general looked at Barbicane anxiously.

  "Well, gentlemen," said the president, "I can only repeat what I said toyou yesterday, don't be uneasy; we shall not want for money."

  Upon this assurance of its president the committee broke up, afterhaving fixed a third meeting for the next evening.