Home Categories science fiction from earth to moon

Chapter 8 Chapter 8 History of the Cannon

from earth to moon 儒勒·凡尔纳 2689Words 2018-03-23
The decision adopted at this meeting caused great repercussions in the outside world.The faint-hearted are a little horrified at the thought of launching a twenty-thousand-pound projectile into space.Everyone is asking each other, what kind of cannon can give enough muzzle velocity to such a heavy thing?The minutes of the second meeting of the Executive Committee can successfully answer these questions. The next evening, the four members of the Cannon Club sat down again at a table with a mountain of sandwiches and tea that surpassed a real ocean.They immediately resumed their discussion, this time cutting out even the opening remarks.

"My dear commissioners," said Barbicane, "we now have to study the cannon we are to make, its length, shape, construction, and weight. We may give it a great volume: but, in spite of the difficulties How great are they, and our industrial talents can easily overcome them. So listen, you should relentlessly raise strong objections. I will not be afraid." The announcement was greeted with murmurs of admiration. "Do not forget where we were discussing yesterday," went on Barbicane, "our problem now takes the form of how to make a cannonball 108 inches in diameter and weighing 20,000 pounds achieve clock an initial velocity of twelve thousand yards."

"Really, that's exactly what it is," echoed Alphaston. "I will go on," continued Barbicane. "What will happen to a cannonball after it is fired into the open air? It will be affected by three independent forces, that is, external resistance, gravity and its own driving force. The external resistance is also That is to say, the resistance of the air is not a very important force. Indeed, the earth's atmosphere is only forty miles thick. A cannonball traveling at 10,000 to 2,000 yards per second travels through it in only five seconds. Time is so short that we can Thinking that the resistance of the atmosphere is insignificant, then, let us now study the gravity of the earth, that is to say, the weight of the shell. We know that the weight is inversely proportional to the square of the distance. In fact, what physics teaches us is: the object moves towards the earth When the surface descends, the speed in the first second is fifteen feet, and if the same body is placed at 257,542 miles, that is, at an altitude equivalent to the distance between the earth and the moon ; its speed in the first second is about half a lini.It could almost be said to be standing still.So we have to gradually overcome the effect of gravity.What method is used to achieve this goal?driving force. "

"Here lies the difficulty," said the staff officer. Yes, therein lies the difficulty," went on the club's chairman, "but we can overcome it, because the propulsion we need depends on the length of the cannon and the quantity of explosives used, and the amount of counterfeit is determined by the cannon. limitations of resistance.So let's study the volume of the cannon today.Of course, there is no limit to the resistance we can give it, since it doesn't need to move. " "That's obvious," said the general. "Until now," said Barbicane, "the longest guns, our great Columbians, have not exceeded twenty-five feet in length, so the size of the guns we have to adopt will surprise many."

"Ah! No problem," cried Maston. "I, I demand a cannon at least half a mile long!" "Half a mile!" cried the staff officer and the general at the same time. "Yes, half a mile long, so it's half as short." "Forget it, Maston," Morgan replied, "you're exaggerating." "No!" replied the quick-tempered secretary aggressively, "I don't know why you accuse me of exaggeration." "Because you ran too far!" "You know, sir," said Maston, Secretary of the Executive Committee, with airs of superiority, "you know, the inventor of the cannon, like the cannon ball, never gets very far!"

The discussion turned into a personal attack, but the chairman intervened. "Calm down, friends, let's do some research. Obviously, what we need is a gun with a very long barrel, because the length of the barrel can increase the expansion of the gas under the shell, but it doesn't need to exceed a certain limit." "Exactly," said the staff officer. "What rule generally applies in such cases? The usual length of the barrel is twenty to twenty-five times the diameter of the shell, and its weight two hundred and thirty-five to two hundred and forty times."

"It's not enough," cried Maston boldly. "I agree, noble friend, that in truth, on this scale, a nine-foot-diameter, twenty-thousand-pound shell would have a barrel of only two hundred and twenty-five feet, and weigh only seven, two million pounds." "That would be ridiculous," Maston said hastily. "It's better to use a pistol!" "I think so too," replied Barbicane, "and I propose to quadruple this length, and make a cannon nine hundred feet long." Several objections were raised by the general and the staff, but this proposal was enthusiastically supported by the Secretary of the Cannon Club, and it was adopted.

"Now," said Alfiston, "what is the thickness of the walls?" "Six feet," answered Barbicane. "Perhaps you are not going to put such a bulky thing on the gun mount," the staff officer asked. "That's a good idea!" said Maston. "Unfortunately, it cannot be done," replied Barbicane. "Yes, I intend to cast the barrel on the ground, throw wrought iron hoops around it, and finally surround it firmly with stone and lime, so that the cannon building can share the surrounding land. The recoil force received. After the gun barrel is cast, carefully flatten and round the surface of the cavity, so as not to allow play ① to exist; I'm strong."

"Uh-huh! Uh-huh!" said Maston, Secretary of the Executive Committee. "Our cannon has succeeded." "Not yet!" answered Barbicane, hushing his impatient friend with a gesture. "Because we don't know what metal to cast the cannon from yet." Then decide now. ""Now I have a suggestion for you. " The entire Executive Committee swallowed a dozen sandwiches each, then forked a cup of tea before resuming the debate. "Honest commissioners," said Barbicane, "our cannon must be tough, hard, resistant to high heat, and insoluble and inoxidized by all kinds of acids."

"Of course there is no doubt," replied the staff officer, "as the quantity of metals we need to use is so great that we should have no difficulty in selecting them." "Very well," said Morgan, "I propose to cast this Colombian gun from the best alloys hitherto known, that is to say, from an alloy of one hundred parts copper, twelve parts tin, and six parts brass." "Friends," continued the chairman, "I admit that this alloy has very good properties; but in the present case, one is too expensive, and the other is difficult to manufacture. Therefore, I think we should use another A fine, but cheap material, made of cast iron. Isn't that your opinion, staff?"

"Exactly," Alphaston replied. "The truth is," continued Barbicane, "that cast-iron is ten times cheaper than bronze, is easily melted, and needs only to be poured into sand-moulds, and the operation takes no time, thus saving both money and time. Besides, this This material is of excellent quality, and I remember that during the war, when Atlanta was besieged, each cast-iron gun fired a thousand rounds every twenty minutes, and the barrel was not damaged." "Cast iron is too brittle, though," says Morgan. "True, but it's very resistant; and besides; I'm sure we can fire without blowing the barrel." "We can shoot and have a clear conscience," Maston said meaningfully. "No doubt," answered Barbicane. "Now ask our noble secretary to calculate the weight of a cannon nine hundred feet long, nine feet inside diameter, and six feet thick. "In a moment," replied Maston. As he had done the night before, he drew a few formulas briskly, and after a minute he said: "The weight of this cannon is sixty-eight thousand and forty tons." "At two cents per pound, the total value of..." "Total value of two hundred and fifty thousand seven hundred and one dollars." Maston, the secretary of the executive committee, the staff and the general all looked worried and said to Barbicane, "Well, gentlemen," said the chairman, "I will repeat what I told you yesterday. You can rest assured. , we won't be short of millions of dollars!" After receiving assurances from the Chairman and hearing his decision to resume the next day, the Executive Committee adjourned.
Press "Left Key ←" to return to the previous chapter; Press "Right Key →" to enter the next chapter; Press "Space Bar" to scroll down.