Tom Swift and His Giant Cannon Part 5

"But--but--" stammered Ned.

"It is only when powder is confined that it explodes," Tom explained.

"If it can burn in the open it's as harmless as water, provided you don't burn too much at once. But put it in something where the resulting gases acc.u.mulate and can't escape, and then--why, you have an explosion--that's all."

"Yes--that's all," remarked Ned, grimly, as he nervously watched the burning stick of powder. Tom let it flame for a few seconds, and then calmly blew it out.

"You know what a little puff black gunpowder gives, if you burn some openly on the ground," went on Tom; "don't you, Ned?"

"Sure, I've often done that."

"But put that same powder in a tight box, and set fire to it, and you have a bang instead of a puff. It's the same way with this powder, only it doesn't even puff, for it burns more slowly.

"An explosion, you see, is the sudden liberation at one time of the gases which result when the powder is burned. If the gases are given off gradually, and in the open, no harm is done. But put a stick like this in, say, a steel box, all closed up, save a hole for the fuse, and what do you have? An explosion. That's the principle of all guns and cannon.

"But say, Ned, I'm getting to be a regular lecturer. I didn't know I was running on so. Why didn't you stop me?"

"Because I was interested. Go on, tell me some more."

"Not now. I want to get this powder in a safe place. I'm a little nervous about it after that fire. You see if it had caught, when tightly packed in the boxes, there would have been a terrific explosion, though it does burn so harmlessly in the open air. Now let me see--"

Tom was interrupted by the postman's whistle, and a little later Eradicate came in with the mail that had been left in the box at the shop door. Tom rapidly looked over the letters.

"Here's the note I want, I think," he said, Selecting one. "Yes, this is it. 'Permission is hereby granted,' he read, 'to Thomas Swift to visit,' and so on, and so on. This is the stuff, Ned!" he cried.

"What is it?"

"A permit to visit the government proving grounds at Sandy Hook, Ned, and see 'em test that new big gun I was telling you about. Hurray!

We'll go down there, and I'll see how my ideas fit in with those of the government's experts."

"Did you say 'we' would go down, Tom?"

"I sure did. You'll go with me; won't you?"

"Well, I hadn't thought very much about it, but I guess I will. When is it?"

"A week from today, and I'm going to need all that time to get ready.

Now let's get busy, and we'll arrange to go to Sandy Hook. I've had trouble enough to get this permit--I guess I'll put it where it won't get lost," and he locked it in a secret drawer of his desk.

Then the lads stored the powder in a safe place, and soon were busy about several matters in the shop.

CHAPTER V

OFF TO SANDY HOOK

"What's the idea of this government test of the big gun, Tom?" asked Ned. "I got so excited about that near-explosion the other day, that I didn't think to ask you all the particulars."

"Why, the idea is to see if the gun will work, and do all that the inventor claims for it," was the answer. "They always put a new gun through more severe tests than anything it will be called on to stand in actual warfare. They want to see just how much margin of safety there is."

"Oh I see. And is this one of the guns that are to be used in fortifying the Panama Ca.n.a.l?"

"Well, Ned, I don't know, exactly. You see, the government isn't telling all its secrets. I a.s.sume that it is, and that's why I'm anxious to see what sort of a gun it is.

"As a matter of fact, I'm going into this thing on a sort of chance, just as dad did when he invested in Mr. Peterson's opal mine."

"Do you think anything will come of that, Tom?"

"I don't know. If we get down to Panama, after I have made my big gun, we may take a run over, and see how he is making out. But, as I said, I'm going into this big cannon business on a sort of gamble. I have heard, indirectly, that Uncle Sam intends to use a new type of gun in fortifying the Panama Ca.n.a.l. It's about forty-nine miles long, you know, and it will take many guns to cover the whole route, as well as to protect the two entrances."

"Not so very many if you make a gun that will shoot thirty miles,"

remarked Ned, with a smile.

"I'm not so sure I can do it," went on Tom. "But, even at that, quite a number of guns will be needed. For if any foreign nation, or any combination of nations, intend to get the ca.n.a.l away from us, they won't make the attack from one point. They'll come at us seven different ways for Sunday, and I've never heard yet of a gun that can shoot seven ways at once. That's why so many will be needed.

"But, as I said, I don't know just what type the Ordnance Department will favor, and I want to get a line. Then, even if I invent a cannon that will outshoot all the others, they may not take mine. Though if they do, and buy a number of them, I'll be more than repaid for my labor, besides having the satisfaction of helping my country."

"Good for you, Tom! I wish it was time to go to Sandy Hook now. I'm anxious to see that big gun. Do you know anything about it?"

"Not very much. I have heard that it is not quite as large as the old sixteen-inch rifle that they had to throw away because of some trouble, I don't know just what. It was impractical, in spite of its size and great range. But this new gun they are going to test is considerably smaller, I understand.

"It was invented by a General Waller, and is, I think, about twelve inches across at the muzzle. In spite of that comparatively small size, it fires a projectile weighing a thousand pounds, or half a ton, and takes five hundred pounds of powder. Its range, of course, no one knows yet, though I have heard it said that General Waller claims it will shoot twenty miles."

"Whew! Some shot!"

"I'm going to beat it," declared Tom, "and I want to do it without making such a monstrous gun that it will be difficult to cast it.

"You see, Ned, there is, theoretically, nothing to prevent the casting of a steel rifled cannon that would be fifty inches across at the muzzle, and making it a hundred feet long. I mean it could be done on paper--figured out and all that. But whether you would get a corresponding increase in power or range, and be able to throw a relatively larger projectile, is something no one knows, for there never has been such a gun made. Besides, the strain of the big charge of powder needed would be enormous. So I don't want merely to make a giant cannon. I want one that will do a giant's work, and still be somewhere in the middle-sized cla.s.s."

"I see. Well, you'll probably get some points at Sandy Hook."

"I think so. We go day after tomorrow."

"Is Mr. Damon going?'

"I think not. If he does I'll have to get another pa.s.s, for mine only calls for two persons. I got it through a Captain Badger, a friend of mine, stationed at the Sandy Hook barracks. He doesn't have anything to do with the coast defense guns, but he got the pa.s.s to the proving grounds for me."

Tom and his chum talked for some time about the prospects for making a giant cannon, and then the young inventor, with Ned's aid, made some powder tests, using some of the explosive that had so nearly caught fire.

"It isn't just what I want," Tom decided, after he had put small quant.i.ties in little steel bombs, and exploded them, at a safe distance, and under a bank of earth, by means of an electric primer.

"Why, Tom, that powder certainly burst the bombs all to pieces," said Ned, picking up a shattered piece of steel.

"I know, but it isn't powerful enough for me. I'm going to send for samples of another kind, and if I can't get what I want I'll make my own powder. But come on now, this stuff gives me a headache. Let's take a little flight in the Humming Bird. We'll go see Mr. Damon," and soon the two lads were in the speedy little monoplane, skimming along like the birds. The fresh air soon blew away their headaches, caused by the fumes from the nitro-glycerine, which was the basis of the powder.

Dynamite will often produce a headache in those who work with it.

Two days later Tom and Ned set off for Sandy Hook.