The resolutions passed at the last meeting produced a great effect out of doors. Timid people took fright at the idea of a shot weighing 20，000 pounds being launched into space；they asked what cannon could ever transmit a sufficient velocity to such a mighty mass.The minutes of the second meeting were destined triumphantly to answer such questions.

“My dear colleagues，”said Barbicane, without further preamble，“the subject now before us is the construction of the engine, its length, its composition, and its weight. It is probable that we shall end by giving it gigantic dimensions；but however great may be the difficulties in the way, our mechanical genius will readily surmount them.Be good enough, then, to give me your attention, and do not hesitate to make objections at the close.I have no fear of them.The problem before us is how to communicate an initial force of 12，000 yards per second to a shell of 108 inches in diameter, weighing 20，000 pounds.Now when a projectile is launched into space, what happens to it?It is acted upon by three independent forces：the resistance of the air, the attraction of the earth, and the force of impulsion with which it is endowed.Let us examine these three forces.The resistance of the air is of little importance.The atmosphere of the earth does not exceed forty miles.Now, with the given rapidity, the projectile will have traversed this in five seconds, and the period is too brief for the resistance of the medium to be regarded otherwise than as insignificant.Proceding, then, to the attraction of the earth, that is, the weight of the shell, we know that this weight will diminish in the inverse ratio of the square of the distance.When a body left to itself falls to the surface of the earth, it falls fifteen feet in the first second；and if the same body were removed 257，542 miles further off, in other words, to the distance of the moon, its fall would be reduced to about half a line in the first second.That is almost equivalent to a state of perfect rest.Our business, then, is to overcome progressively this action of gravitation.The mode of accomplishing that is by the force of impulsion.”

“There's the difficulty，”broke in the major.

“True，”replied the president；“but we will overcome that, for the force of impulsion will depend on the length of the engine and the powder employed, the latter being limited only by the resisting power of the former. Our business, then, today is with the dimensions of the cannon.”

“Now, up to the present time，”said Barbicane，“our longest guns have not exceeded twenty-five feet in length. We shall therefore astonish the world by the dimensions we shall be obliged to adopt.It must evidently be, then, a gun of great range, since the length of the piece will increase the detention of the gas accumulated behind the projectile；but there is no advantage in passing certain limits.”

“Quite so，”said the major.“What is the rule in such a case?”

“Ordinarily the length of a gun is twenty to twenty-five times the diameter of the shot, and its weight two hundred and thirty-five to two hundred and forty times that of the shot.”

“That is not enough，”cried J. T.Maston impetuously.

“I agree with you, my good friend；and, in fact, following this proportion for a projectile nine feet in diameter, weighing 30，000 pounds, the gun would only have a length of two hundred and twenty-five feet, and a weight of 7，200，000 pounds.”

“Ridiculous！”rejoined J. T.Maston.“As well take a pistol.”

“I think so too，”replied Barbicane；“that is why I propose to quadruple that length, and to construct a gun of nine hundred feet.”

The general and the major offered some objections；nevertheless, the proposition, actively supported by the secretary, was definitely adopted.

“But，”said Elphinstone，“what thickness must we give it?”

“A thickness of six feet，”replied Barbicane.

“You surely don't think of mounting a mass like that upon a carriage?”asked the major.

“It would be a superb idea, though，”said J. T.Maston.

“But impracticable，”replied Barbicane.“No, I think of sinking this engine in the earth alone, binding it with hoops of wrought iron, and finally surrounding it with a thick mass of masonry of stone and cement. The piece once cast, it must be bored with great precision, so as to preclude any possible windage.So there will be no loss whatever of gas, and all the expansive force of the powder will be employed in the propulsion.”

“One simple question，”said Elphinstone；“is our gun to be rifled?”

“No, certainly not，”replied Barbicane；“we require an enormous initial velocity；and you are well aware that a shot quits a rifled gun less rapidly than it does a smooth-bore.”

“True，”rejoined the major.

The committee here adjourned for a few minutes to tea and sandwiches, the discussion being renewed.

“Gentlemen，”said Barbicane，“we must now take into consideration the metal to be employed. Our cannon must be possessed of great tenacity, great hardness, be infusible by heat, indissoluble, and inoxidable by the corrosive action of acids.”

“There is no doubt about that，”replied the major；“and as we shall have to employ an immense quantity of metal, we shall not be at a loss for choice.”

“Well, then，”said Morgan，“I propose the best alloy hitherto known, which consists of one hundred parts of copper, twelve of tin, and six of brass.”

“I admit，”replied the president，“that this composition has yielded excellent results, but in the present case it would be too expensive, and very difficult to work. I think, then, that we ought to adopt a material excellent in its way and of low price, such as cast iron.What is your advice, major?”

“I quite agree with you，”replied Elphinstone.

“In fact，”continued Barbicane，“cast iron costs ten times less than bronze；it is easy to cast, it runs readily from the moulds of sand, it is easy of manipulation, it is at once economical of money and of time. In addition, it is excellent as a material, and I well remember that during the war, at the siege of Atlanta, some iron guns fired one thousand rounds at intervals of twenty minutes without injury.”

“Cast iron is very brittle, though，”replied Mogran.

“Yes, but it possesses great resistance. I will now ask our worthy secretary to calculate the weight of a cast-iron gun with a bore of nine feet and a thickness of six feet of metal.”

“In a moment，”replied J. T.Maston.Then, dashing off some algebraical formulae with marvelous facility, in a minute or two he declared the following result：

“The cannon will weigh 68，040 tons. And, at two cents a pound, it will cost—”

“Two million five hundred and ten thousand seven hundred and one dollars.”

J. T.Maston, the major, and the general regarded Barbicane with uneasy looks.

“Well, gentlemen，”replied the president，“I repeat what I said yesterday. Make yourselves easy；the millions will not be wanting.”

With this assurance of their president the committee separated, after having fixed their third meeting for the following evening.

这次会议所做出的决定在外界引起了极大的反响。一些胆小的人一想到要将一颗重达两万磅的炮弹发往太空，不免有点儿惶恐不安。有的人在寻思什么样的大炮能够具有如此大的威力，让这么大个儿的炮弹产生足够大的初速度。委员会第二次会议记录将很好地回答种种疑问。

“亲爱的同事们，”巴比凯恩说道，“我们现在就来讨论一下大炮制造的问题。它需要多长，什么结构，重量是多少等。我们有可能得造一门巨型炮，但是，无论困难有多大，我们的工业精英们都会战而胜之的。请大家注意听我说，如有反对意见，请立即提出来。我不害怕反对意见！现在的问题是这样的：如何让一颗直径为一百零八英寸、重达两万磅的炮弹产生每秒一万两千码的初速度？当一颗炮弹被发射到空中去，会是个什么情况呢？它会为三种独立的力量所左右：外界阻力、地球引力和驱使它的推动力。让我们来研究一下这三种力量。外界阻力，也就是空气阻力，影响并不大。其实，地球大气层的厚度只有四十英里。而炮弹的速度高达每秒一万两千码，五秒钟就穿过去了，时间很短，以至外界阻力可以说是微乎其微的。再来看一下地球引力，也就是炮弹的重力问题。我们知道，这个重力是与距离的平方成反比的。当一个物体呈自由落体状坠落到地球表面的时候，它在第一秒钟时下降十五英尺；而这同样的物体被移到二十五万七千五百四十二英里的远处，也就是说，移到月球所在的那么远的地方去的话，它的下降幅度在第一秒钟时将减小到半法分[25]左右。这几乎等于静止不动了。因此，我们需要逐渐克服重力作用。怎么才能如愿以偿呢？利用推动力。”

“这就是困难之所在。”少校紧接着说道。

“没错，这确实是困难之所在，”巴比凯恩继续说道，“但是，我们一定会战胜它的，因为这个对我们来说必不可少的推动力将由大炮的长度以及所使用的炮弹火药的多少来决定，而后者又是受到前者的抗力限制的。因此，我们今天就要研究一下大炮体积的大小问题。”

“到目前为止，”巴比凯恩接着说道，“最长的那些大炮，并没有超过二十五英尺，而我们将不得不制造的体积巨大的大炮，会让世人惊讶不已。很明显，必须拥有一门炮身很长的大炮，因为炮身越长，炮弹底下聚集的气体就越多；但是也得有一定的限度，超过了也没有必要。”

“太对了。”少校说道，“在这种情况下，应该采用一些什么样的标准呢？”

“一般来说，一门大炮的长度是炮弹直径的二十到二十五倍，重量是炮弹的两百三十五到两百四十倍。”

“这可不够。”J.T.马斯顿急躁地大声嚷嚷道。

“我同意，是不够，尊敬的朋友。确实，按照这个比例，发射一颗直径九英尺、重三万磅的炮弹所需的大炮只不过长两百二十五英尺，重七百二十万磅。”

“这也太小了，简直就像一把手枪！”J.T.马斯顿说。

“我也这么认为，”巴比凯恩回应道，“因此我想把它的长度扩大到四倍，造一门长九百英尺的大炮。”

将军和少校提出了点异议；但是，巴比凯恩的这一建议得到了大炮俱乐部秘书的热烈支持，最后被采纳了。

“但是，”埃尔菲斯通说，“炮管壁的厚度应该是多少呢？”

“六英尺厚。”巴比凯恩回答道。

“您大概不会认为得把这么个大玩意儿支到炮架上去吧？”少校问道。

“可是，那才壮观呀！”J.T.马斯顿说。

“不过，不好操作，”巴比凯恩说道，“我想还是把这门大炮就浇铸在地上，用一圈一圈的铸铁把它箍紧，再用石头和石灰给它砌上厚厚的炮座。炮身一旦铸成，就要仔细地铰好炮膛[26]，量好内径，以防止炮弹漏气[27]，这样就不会浪费任何一点气体，火药爆炸产生的力都将变成推动力。”

“我有一个小小的疑问，”埃尔菲斯通说，“这门加农炮—榴弹炮—迫击炮混合体有没有膛线呀？”

“没有，当然没有。”巴比凯恩回答道，“我们必须让它具有一个非常大的初速度；你们很清楚，有膛线的炮管发射的炮弹没有光滑炮管发射的速度快。”

“没错。”

委员会的四名成员每人都吃了三明治，又喝了茶，然后又开始讨论起来。

“先生们，”巴比凯恩说道，“我们现在必须考虑一下使用哪种金属。我们的大炮必须具有抗断裂性极大，硬度高，高温耐熔，遇酸不溶解、不氧化的特性。”

“这些都不成问题，”少校回答道，“而且，因为必须使用大量的金属材料，选择起来还不能盲目。”

“那好！”摩根说道，“我建议用迄今为止已知的最好的合金，也就是说，由一百份铜、十二份锡和六份黄铜组成的合金。”

“我承认，”主席说道，“这种组合结果非常好，但是，照目前的情况来说，它的造价太昂贵，制造起来也极其繁难。因此，我想，必须采用一种性能极好却价格低廉的材料，比如铸铁。您是不是这个想法，少校？”

“正是。”埃尔菲斯通回答道。

“确实，”巴比凯恩接着说道，“铸铁的造价只有铜的十分之一，而且它很容易熔化，在砂模里简单地浇铸即可，操作起来极其快捷，因此，既省钱又省时。另外，这种材质绝佳。我记得战争期间，在围攻亚特兰大的时候，那些铸铁大炮每门炮每隔二十分钟便发射一次，共射出一千颗炮弹，而大炮却毫发无损。”

“可是铸铁很容易断裂。”摩根说道。

“那倒是，不过，它有极强的抗力。因此，我要请我们尊敬的秘书计算一下，一门长九百英尺、内径九英尺、炮筒壁厚六英尺的铸铁大炮有多重。”

“马上就能算出来。”J.T.马斯顿回答说。然后，他非常熟练地列出公式来，一分钟之后，他说道：

“这门大炮将重达六万八千零四十吨。如果按每磅两美分来计算，得——”

“两百五十一万七百零一美元。”

J. T.马斯顿、少校和将军神情焦虑地看着巴比凯恩。

“好！先生们，”主席说道，“我要把我昨天跟你们说的重复一遍，请你们放宽心，我们并不缺钱！”

主席做了如此保证之后，委员会的成员们又决定在第二天晚上举行第三次会议，然后便散会了。