"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 Canal?"
"Well, Ned, I don't know, exactly. You see, the government isn't telling all its secrets. I assume 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 Canal. 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 canal 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 class."
"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 pass, 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 pass 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 quantities 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.
This long, neck-like strip of land on the New Jersey coast is, as most of you know, one of the principal defenses of our country.
Foreign vessels that steam into New York harbor first have to pass the line of terrible guns that, back of the earth and concrete defenses, look frowningly out to sea. It is a wonderful place.
On the Sandy Hook Bay side of the Hook there is a life-saving station. Right across, on the sea side, are the big guns. Between are the barracks where the soldiers live, and part of the land is given over to a proving ground, where many of the big guns are taken to be tested.
Tom and Ned reached New York City without incident of moment, and, after a night spent at a hotel, they went to the Battery, whence the small government steamer leaves every day for Sandy Hook. It is a trip of twenty-one miles, and as the bay was rather rough that day, Tom and Ned had a taste of a real sea voyage. But they were too experienced travelers to mind that, though some other visitors were made quite ill.
A landing was made on the bay side of the Hook, it being too rough to permit of a dock being constructed on the ocean side.
"Now we'll see what luck we have," spoke Tom, as he and Ned, inquiring the way to the proving grounds from a soldier on duty, started for them. On the way they passed some of the fortifications.
"Look at that gun!" exclaimed Ned, pointing to a big cannon which seemed to be crouched down in a sort of concrete pit. "How can they fire that, Tom? The muzzle points directly at the stone wall. Does the wall open when they want to fire?"
"No, the gun raises up, peeps over the wall, so speak, shoots out its projectile, and then crouches down again."
"Oh, you mean a disappearing gun."
"That's it, Ned. See, it works by compressed air," and Tom showed his chum how, when the gun was loaded, the projectile in place, and the breech-block screwed fast, the officer in charge of the firing squad would, on getting the range from the soldier detailed to calculate it, make the necessary adjustments, and pull the lever.
The compressed air would fill the cylinders, forcing the gun to rise on toggle-jointed arms, so that the muzzle was above the bomb-proof wall. Then it would be fired, and sink back again, out of sight of the enemy.
The boys looked at several different types of big rifled cannon, and then passed on. They could hear firing in the distance, some of the explosions shaking the ground.
"They're making some tests now," said Tom, hurrying forward.
Ned followed until, passing a sort of machine shop, the lads came to where a sentry paced up and down a concrete walk.
"Are these the proving grounds?" asked Tom. "This is the entrance to them," replied the soldier, bringing his rifle to "port," according to the regulations. "What do you want?"
"To go in and watch the gun tests," replied Tom. "I have a permit," and he held it out so the soldier could see it.
"That permit is no good here;" the sentry exclaimed.
"No good?" faltered Tom.
"No, it has to be countersigned by General Waller. And, as he's on the proving grounds now, you can't see him. He's getting ready for the test of his new cannon."
"But that's just what we want to see!" cried Tom. "We want to get in there purposely for that. Can't you send word to General Waller?"
"I can't leave my post," replied the sentry, shortly. "You'll have to come another time, when the General isn't busy. You can't get in unless he countersigns that permit."
"Then it may be too late to witness the test," objected the young inventor. "Isn't there some way I can get word to him?"
"I don't think so," replied the sentry. "And I'll have to ask you to leave this vicinity. No strangers are allowed on the proving grounds without a proper pass."
Tom looked at Ned in dismay. After all their work and planning, to be thus thwarted, and by a mere technicality! As they stood there, hardly knowing what to do, the sound of a tremendous explosion came to their ears from behind the big pile of earth and concrete that formed the bomb-proof around the testing ground.
"What's that?" cried Ned, as the earth shook.
"Just trying some of the big guns," explained the sentry, who was not a bad-natured chap. He had to do his duty. "You'd better move on," he suggested. "If anything happens the government isn't responsible, you know."
"I wish there was some way of getting in there," murmured Tom.
"You can see General Waller after the test, and he will probably countersign the permit," explained the sentry.
"And we won't see the test of the gun I'm most interested in," objected Tom. "If I could only—"
He stopped as he noticed the sentry salute someone coming up from the rear. Tom and Ned turned to behold a pleasant-faced officer, who, at the sight of the young inventor, exclaimed:
"Well, well! If it isn't my old friend Tom Swift! So you got here on my permit after all?"
"Yes, Captain Badger," replied the lad, and then with a rueful face he added: "But it doesn't seem to be doing me much good. I can't get into the proving grounds."
"You can't? Why not?" and he looked sharply at the sentry.
"Very sorry, sir," spoke the man on guard, "but General Waller has left orders, Captain Badger, that no outsiders can enter the proving grounds when his new gun is being tested unless he countersigns the permits. And he's engaged just now. I'm sorry, but—"
"Oh, that's all right, Flynn," said Captain Badger. "It isn't your fault, of course. I suppose there is no rule against my going in there?" and he smiled.
"Certainly not, sir. Any officer may go in," and the guard stepped to one side.
"Let me have that pass, Tom, and wait here for me," said the Captain. "I'll see what I can do for you," and the young officer, whose acquaintance Tom had made at the tests when the government was purchasing some aeroplanes for the army, hurried off.
He came back presently, and by his face the lads knew he had been successful.
"It's all right," he said with a smile. "General Waller countersigned the pass without even looking at it. He's so excited over the coming test of his gun that he hardly knows what he is doing. Come on in, boys. I'll go with you."
"Then they haven't tested his gun yet?" Asked Tom, eagerly, anxious to know whether he had missed anything.
"No, they're going to do so in about half an hour. You'll have time to look around a bit. Come on," and showing the sentinel the counter-signed pass, Captain Badger led the two youths into the proving grounds.
Tom and Ned saw so much to interest them that they did not know at which to look first. In some places officers and firing squads were testing small-calibre machine guns, which shot off a round with a noise like a string of firecrackers on the Chinese New Year's. On other barbettes larger guns were being tested, the noise being almost deafening.
"Stand on your tiptoes, and open your mouth when you see a big cannon about to be fired," advised Captain Badger, as he walked alongside the boys.
"What good does that do?" inquired Ned.
"It makes your contact with the earth as small as possible—standing on your toes," the officer explained, "and so reduces the tremor. Opening your mouth, in a measure, equalizes the changed air pressure, caused by the vacuum made when the powder explodes. In other words, you get the same sort of pressure down inside your throat, and in the tubes leading to the ear—the same pressure inside, as outside.
"Often the firing of big guns will burst the ear drums of the officers near the cannon, and this may often be prevented by opening the mouth. It's just like going through a deep tunnel, or sometimes when an elevator descends quickly from a great height. There is too much outside air pressure on the ear drums. By opening your mouth and swallowing rapidly, the pressure is nearly equaled, and you feel no discomfort."
The boys tried this when the next big gun was fired, and they found it true. They noticed quite a crowd of officers and men about a certain large barbette, and Captain Badger led them in that direction.
"Is that General Waller's gun?" asked Tom.
"That's where they are going to test it," was the answer.
Eagerly Tom and Ned pressed forward. No one of the many officers and soldiers grouped about the new cannon seemed to notice them. A tall man, who seemed very nervous and excited, was hurrying here and there, giving orders rapidly.
"How is that range now?" he asked. "Let me take a look! Are you sure the patrol vessels are far enough out? I think this projectile is going farther than any of you gentlemen have calculated."
"I believe we have correctly estimated the distance," answered someone, and the two entered into a discussion.
"That excited officer is General Waller," explained Captain Badger, in a low voice, to Tom and Ned.
"I guessed as much," replied the young inventor. Then he went closer to get a better look at the big cannon.
I say big cannon, and yet it was not the largest the government had. In fact, Tom estimated the calibre to be less than twelve inches, but the cannon was very long—much longer in proportion than guns of greater muzzle diameter. Then, too, the breech, or rear part, was very thick and heavy.
"He must be going to use a tremendous lot of powder," said Tom.
"He is," answered Captain Badger. "Some of us think he is going to use too much, but he says it is impossible to burst his gun. He wants to make a long-range record shot, and maybe he will."
"That's a new kind of breech block," commented Tom, as he watched the mechanism being operated.
"Yes, that's General Waller's patent, too. They're going to fire soon."
I might explain, briefly, for the benefit of you boys who have never seen a big, modern cannon, that it consists of a central core of cast steel. This is rifled, just as a small rifle is bored, with twisted grooves throughout its length. The grooves, or rifling, impart a twisting motion to the projectiles, and keep them in a straighter line.
After the central core is made and rifled, thick jackets of steel are "shrunk" on over the rear part of the gun. Sometimes several jackets are put on, one over the other, to make the gun stronger.
If you have ever seen a blacksmith put a tire on a wheel you will understand what I mean. The tire is heated, and this expands it, or makes it larger. It is put on hot, and when it cools it shrinks, getting smaller, and gripping the rim of the wheel in a strong embrace. That is what the jackets of steel do to the big guns.
A big rifled cannon is loaded from the rear, or breech, just as is a breech-loading shotgun or rifle. That is, the cannon is opened at the back and the projectile is put in by means of a derrick, for often the projectiles weigh a thousand pounds or more. Next comes the powder—hundreds of pounds of it—and then it is necessary to close the breech.
The breech block does this. That block is a ponderous piece of steel, quite complicated, and it swings on a hinge fastened to one side of the rear of the gun. Once it is swung back into place, it is made fast by means of screw threads, wedges or in whatever way the inventor of the gun deems best.
The breech block must be very strong, and held firmly in place, or the terrific force of the powder would blow it out, wreck the gun and kill those behind it. You see, the breech block really stands a great part of the strain. The powder is between it and the projectile, and there is a sort of warfare to see which will give way—the projectile or the block. In most cases the projectile gracefully bows, so to speak, and skips out of the muzzle of the gun, though sometimes the big breech block will be shattered.
With eager eyes Tom and Ned watched the preparations for firing the big gun. The charge of powder was hoisted out of the bomb-proof chamber below the barbette, and then the great projectile was brought up in slings. At the sight of that Tom realized that the gun was no ordinary one, for the great piece of steel was nearly three feet long, and must have weighed nearly a thousand pounds. Truly, much powder would be needed to send that on its way.
"I'm afraid, General, that you are using too much of that strong powder," Tom heard one officer say to the inventor of the gun. "It may burst the breech."
"Nonsense, Colonel Washburn. I tell you it is impossible to burst my gun—impossible, sir! I have allowed for every emergency, and calculated every strain. I have a margin of safety equal to fifty per cent."
"Very well, I hope it proves a success."
"Of course it will. It is impossible to burst my gun! Now, are we ready for the test."
The gun was rather crude in form, not having received its final polish, and it was mounted on a temporary carriage. But even with that Tom could see that it was a wonderful weapon, though he thought he would have put on another jacket toward the muzzle, to further strengthen that portion.
"I'm going to make a gun bigger than that," said Tom to Ned. He spoke rather louder than he intended, and, as it was at a moment when there was a period of silence, the words carried to General Waller, who was at that moment near Tom.
"What's that?" inquired the rather fiery-tempered officer, as he looked sharply at our hero.
"I said I was going to make a larger gun than that," repeated Tom, modestly.
"Sir! Do you know what you are saying? How did you come in here, anyhow? I thought no civilians were to be admitted today! Explain how you got here!"
Tom felt an angry flush mounting to his cheeks.
"I came in here on a pass countersigned by you," he replied.
"A pass countersigned by me? Let me see it."
Tom passed it over.
"Humph, it doesn't seem to be forged," went on the pompous officer. "Who are you, anyhow?"
"Tom Swift."
"Hum!"
"General Waller, permit me to introduce Tom Swift to you," spoke Captain Badger, stepping forward, and trying not to smile. "He is one of our foremost inventors. It is his type of monoplane that the government has adopted for the coming maneuvers at Panama, you may recall, and he was very helpful to Uncle Sam in stopping that swindling on the border last year—Tom and his big searchlight. Mr. Swift, General Waller," and Captain Badger bowed as he completed the introduction.
"What's that. Tom Swift here? Let me meet him!" exclaimed an elderly officer coming through the crowd. The others parted to make way for him, as he seemed to be a person of some importance, to judge by his uniform, and the medals he wore.
"Tom Swift here!" he went on. "I want to shake hands with you, Tom! I haven't seen you since I negotiated with you for the purchase of those submarines you invented, and which have done such splendid service for the government. Tom, I'm glad to see you here today."
The face of General Waller was a study in blank amazement.
There were murmurs throughout the throng about the big gun, as the officer approached Tom Swift and shook hands with him.
"What have you in mind now, Tom, that you come to Sandy Hook?" the much-medaled officer asked.
"Nothing much, Admiral," answered our hero.
"Oh, yes, you have!" returned Admiral Woodburn, head of the naval forces of Uncle Sam. "You've got some idea in your head, or you wouldn't come to see this test of my friend's gun. Well, if you can invent anything as good for coast defense, or even interior defense, as your submarines, it will be in keeping with what you have done in the past. I congratulate you, General Waller, on having Tom Swift here to give you the benefit of some of his ideas."
"I—I haven't had the pleasure of meeting Mr. Swift before," said the gun inventor, stiffly. "I did not recognize his name when I countersigned his pass."
It was plain that the greeting of Tom by Admiral Woodburn had had a marked effect in changing sentiment toward our hero. Captain Badger smiled as he noticed with what different eyes the gun inventor now regarded the lad.
"Well, if Tom Swift gives you any points about your gun, you want to adopt them," went on the Admiral. "I thought I knew something about submarines, but Tom taught me some things, too; didn't you, Tom?"
"Oh, it was just a simple matter, Admiral," said Tom, modestly. "Just that little point about the intake valves and the ballast tanks."
"But they changed the whole matter. Yes, General, you take Tom's advice—if he gives you any."
"I don't know that I will need any—as yet," replied General Waller. "I am confident my gun will be a success as it is at present constructed. Later, however, if I should decide to make any changes, I will gladly avail myself of Mr. Swift's counsel," and he bowed stiffly to Tom. "We will now proceed with the test," he went on. "Kindly send a wireless to the patrol ships that we are about to fire, and ask them to note carefully where the projectile falls."
"Very good, sir," spoke the officer in immediate charge of the matter, as he saluted. Soon from the aerials snapped the vicious sparks that told of the wireless telegraph being worked.
I might explain that near the spot where the projectile was expected to fall into the sea—about fifteen miles from Sandy Hook—several war vessels were stationed to warn shipping to give the place a wide berth. This was easy, since the big gun had been aimed at a spot outside of the steamship lanes. Aiming the rifle in a certain direction, and giving it a definite angle of inclination, made it practically certain just where the shot would fall. This is called "getting the range," and while, of course, the exact limit of fire of the new gun was not known, it had been computed as nearly as possible.
"Is everything ready now?" asked General Waller, while Tom was conversing with his friends, Captain Badger and Admiral Woodburn, Ned taking part in the conversation from time to time.
"All ready, sir," was the assurance. The inventor was plainly nervous as the crucial moment of the test approached. He went here and there upon the barbette, testing the various levers and gear wheels of the gun.
The projectile and powder had been put in, the breech-block screwed into place, the primer had been inserted, and all that remained was to press the button that would make the electrical connection, and explode the charge. This act of firing the gun had been intrusted to one of the soldiers, for General Waller and his brother officers were to retire to a bomb-proof, whence they would watch the effect of the fire, and note the course of the projectile.
"It seems to me," remarked Ned, "that the soldier who is going to fire the gun is in the most danger."
"He would be—if it exploded," spoke Tom, for his officer friends had joined their colleagues, most of whom were now walking toward the shelter. "But I think there is little danger.
"You see, the electric wires are long enough to enable him to stand some distance from the gun. And, if he likes, he can crouch behind that concrete wall of the next barbette. Still, there is some chance of an accident, for, no matter how carefully you calculate the strain of a bursting charge of powder, and how strongly you construct the breech-block to stand the strain, there is always the possibility of a flaw in the metal. So, Ned, I think we'll just go to the bomb-proof ourselves, when we see General Waller making for the same place."
"I suppose," remarked Ned, "that in actual warfare anyone who fired one of the big guns would have to stand close to it—closer than that soldier is now."
"Oh, yes—much," replied Tom, as he watched General Waller giving the last instructions to the private who was to press the button. "Only, of course, in war the guns will have been tested, and this one has not. Here he comes; I guess we'd better be moving."
General Waller, having assured himself that everything was as right as possible, had given the last word to the private and was now making his way toward the bomb-proof, within which were gathered his fellow-officers and friends.
"You had better retire from the immediate vicinity of the gun," said its inventor to Tom and Ned, as he passed them. "For, while I have absolute confidence in my cannon, and I know that it is impossible to burst it, the concussion may be unpleasant at such close range."
"Thank you," said Tom. "We are going to get in a safe place."
He could not refrain from contrasting the general's manner now with what it had been at first.
As for Ned, he could not help wondering why, if the inventor had such absolute faith in his weapon, he did not fire it himself, even at the risk of a "concussion."
How it happened was never accurately known, as the soldier declared positively—after he came out of the hospital—that he had not pressed the button. The theory was that the wires had become crossed, making a short circuit, which caused the gun to go off prematurely.
But suddenly, while Tom, Ned and General Waller were still some distance away from the bomb-proof, there was a terrific explosion. It seemed as if the very foundations of the fortifications would be shattered. There was a roaring in the air—a hot burst of flame, and instantly such a vacuum was created that Tom and Ned found themselves gasping for breath.
Dazed, shaken in every bone, with their muscles sore, they picked themselves up from the ground, along which they had been blown with great force in the direction of the bomb-proof. Even as Tom struggled to his feet, intending to run to safety in fear of other explosions, he realized what had happened.
"What—what was it?" cried Ned, as he, too, arose.
"The gun burst!" yelled Tom.
He looked to the left and saw General Waller picking himself up, his uniform torn, and blood streaming from a cut on his face. At the same instant Tom was aware of the body of a man flying through the air toward a distant grass plot, and the young inventor recognized it as that of the soldier who had been detailed to fire the great cannon.
Almost instantaneously as everything happened, Tom was aware of noticing several things, as though they took place in sequence. He looked toward where the gun had stood. It was in ruins. The young inventor saw something, which he took to be the projectile, skimming across the sea waves, and he had a fleeting glimpse of the greater portion of the immense weapon itself sinking into the depths of the ocean.
Then, coming down from a great height in the air, he saw a dark object. It was another piece of the cannon that had been hurled skyward.
"Look out!" Tom yelled, instinctively, as he staggered toward the bomb-proof, Ned following.
He saw a number of officers running out to assist General Waller, who seemed too dazed to move. Many of them had torn uniforms, and not a few were bleeding from their injuries. Then the air seemed filled with a rain of small missiles—stones, dirt, gravel and pieces of metal.
"Are you much hurt, Ned?"
Tom Swift bent anxiously over the prostrate form of his chum. A big piece of the burst gun had fallen close to Ned—so close, in fact, that Tom, who saw it as he neared the entrance to the bomb-proof, shuddered as he raced back. But there was no sign of injury on his chum.
"Are you much hurt, Ned?"
The lad's eyes opened. He seemed dazed.
"No—no, I guess not," he answered, slowly. "I—I guess I'm as much scared as hurt, Tom. It was the wind from that big piece that knocked me down. It didn't actually hit me."
"No, I should say not," put in Captain Badger, who had run out toward the two lads. "If it had hit you there wouldn't have been much of you left to tell the tale," and he nodded toward the big piece of metal Tom had seen coming down from the sky. That part of the cannon forming a portion of the breech had buried itself deep in the earth. It had landed close to Ned—so close that, as he said, the wind of it, as well as the concussion, perhaps, had thrown him with enough force to send the breath from him.
"Glad to hear that, old man!" exclaimed Tom, with a sigh of relief. "If you'd been hurt I should have blamed myself."
"That would have been foolish. I took the same chance that you did," answered Ned, as he arose, and limped off between the captain and Tom.
A great silence seemed to have followed the terrific report. And now the officers and soldiers began to recover from the stupor into which the accident had thrown them. Sentries began pouring into the proving grounds from other portions of the barracks, and an ambulance call was sent in.
General Waller's comrades had hurried out to him, and were now leading him away. He did not seem to be much hurt, though, like many others, he had received numerous cuts and scratches from bits of stone and gravel scattered by the explosion, as well as from small bits of metal that were thrown in all directions.
"Are you hurt, General?" asked Admiral Woodburn, as he put his arm about the shoulder of the inventor.
"No—that is to say, I don't think so. But what happened? Did they fire some other gun in our direction by mistake?"
For a moment they all hesitated. Then the Admiral said, gently:
"No, General. It was your own gun—it burst."
"My gun! My gun burst?"
"That was it. Fortunately, no one was killed."
"My gun burst! How could that happen? I drew every plan for that gun myself. I made every allowance. I tell you it was impossible for it to burst!"
"But it did burst, General," went on the Admiral. "You can see for yourself," and he turned around and waved his hand toward the barbette where the gun had been mounted. All that remained of it now was part of the temporary carriage, and a small under-portion of the muzzle. The entire breech, with the great block, had been blown into fragments, so powerful was the powder used. The projectile one watcher reported, had gone about three hundred yards over the top of the barbette and then dropped into the sea, very little of the force of the explosive having been expended on that. A large piece of the gun had also been lost in the water off shore.
"My gun burst! My gun burst!" murmured General Waller, as if unable to comprehend it. "My gun burst—it is impossible!"
"But it did," spoke Admiral Woodburn, softly. "Come, you had better see the surgeon. You may be more seriously injured than you think."
"Was anyone else hurt?" asked the inventor, listlessly. He seemed to have lost all interest, for the time being.
"No one seriously, as far as we can learn," was the answer.
"What of the man who fired the gun?" inquired the General.
"He was blown high into the air," said Tom. "I saw him."
"But he is not injured beyond some bruises," put in one of the ambulance surgeons. "We have taken him to the hospital. He fell on a pile of bags that had held concrete, and they saved him. It was a miraculous escape."
"I am glad of it," said General Waller. "It is bad enough to feel that I made some mistake, causing the gun to burst; but I would never cease to reproach myself if I felt that the man who fired it was killed, or even hurt."
His friends led him away, and Tom and Ned went over to look at what remained of the great gun. Truly, the powder, expending its force in a direction not meant for it, had done terrific havoc. Even part of the solid concrete bed of the barbette had been torn up.
An official inquiry was at once started, and, while it would take some time to complete it (for the parts of the gun remaining were to be subjected to an exhaustive test to determine the cause of the weakness), it was found that there was some defect in the wiring and battery that was used to fire the charge.
The soldier who was to press the button was sure he had not done so, as he had been ordered to wait until General Waller gave the signal from the bomb-proof. But the gun went off before its inventor reached that place of safety. Just what had caused the premature discharge could never be learned, as part of the firing apparatus had been blown to atoms.
"Well, Tom, what do you think of it?" asked Ned, who had now fully recovered from the shock. The two were about to leave the proving grounds, having seen all that they cared to.
"I don't know just what to think," was the answer. "It sure was a big explosion, and it goes to prove that, no matter how many calculations you make, when you try a new powder in a new gun you don't know what's going to happen, until after it has happened—and then it's too late. It's a big problem, Ned."
"Do you think you can solve it? Are you still going on with your plan to build the biggest cannon ever made?"
"I sure am, Ned, though I don't know that I'll make out any better than General Waller did. It's too bad his was a failure; but I think I see where he made some mistakes."
"Oh, you do; eh?" suddenly exclaimed a voice, and from a nearby parapet, where he had gone to look at one of the pieces of his gun, stepped General Waller. "So you think I made some mistakes, Tom Swift? Where, pray?"
"In making the breech. The steel jackets were of uneven thickness, making the strain unequal. Then, too, I do not think the powder was sufficiently tested. It was probably of uneven strength. That is only my opinion, sir."
"Well, you are rather young to give opinions to men who have devoted almost all their lives to the study of high explosives."
"I realize that, sir; but you asked me for my opinion. I shall hope to profit by your mistakes, too. That is one reason I wanted to see this test."
"Then you are seriously determined to make a gun that you think will rival mine."
"I am, General Waller."
"For what purpose—to sell to some foreign government?"
"No, sir!" cried Tom, with flashing eyes. "If I am successful in making a cannon that will fire the longest shots on record, I shall offer it to Uncle Sam first of all. If he does not want it, I shall not dispose of it to any foreign country!"
"Hum! Well, I don't believe you'll succeed. I intend to rebuild my gun at once, though I may make some changes in it. I am sure I shall succeed the next time. But as for you—a mere youth—to hope to rival men who have made this problem a life-study—it is preposterous, sir! Utterly preposterous!" and he uttered these words much as he had declared that it was impossible for his gun to burst, even after it was in fragments.
"Come on, Ned," said Tom, in a low voice. "We'll go back home."
"Bless my cartridge belt, Tom, you don't really mean to say that stuff is powder!" exclaimed Mr. Damon.
"That's what I hope it will prove to be—and powerful powder at that."
"Why, it looks more like excelsior than anything else," went on the odd man, gingerly taking up some yellowish shreds in his fingers.
"And it will burn as harmlessly as excelsior in the open air," went on Tom. "But I hope to prove, when it is confined in a chamber, that it will be highly explosive. I'm going to make a test of it soon."
"Give me good notice, so I can get over in the next State!" exclaimed Ned Newton, with a laugh.
This was several days after our friends had returned from the disastrous gun test at Sandy Hook. Tom had at once gotten to work on the problem that confronted him—a problem of his own making—to build a giant cannon that would make the longest shots on record. And he had first turned his attention to the powder, or explosive, to be used.
"For," he said, "there is no use having a big gun unless you can fire it. And the gun I am planning will need something more powerful in the powder line than any I've ever heard of."
"Stronger than the kind General Waller used?" inquired Ned.
"Yes, but I'll make my cannon correspondingly stronger, too, so there will be no danger."
"Bless my shoe buttons!" exclaimed Mr. Damon. "You boys must have had your nerve with you to stay around Sandy Hook after that gun went up in the air."
"Oh, the danger was all over soon after it began," spoke Tom, with a smile. "But now I'm going to test some of this powder. If you want to run away, Mr. Damon, I'll have Koku take you up in one of the airships, and you'll certainly be safe a mile or so in the air," for Tom had instructed his giant servant how to run one of the simpler biplanes.
"No—no, Tom, I'll stick!" exclaimed the eccentric man. "I'll not promise not to hide behind the fence, or something like that, though, Tom; but I'll stick."
"So will I," added Ned. "How are you going to make the test, Tom?"
"I'll tell you in a minute. I want to do a little figuring first."
Tom had, before going to Sandy Hook, made some experiments in powder manufacturing, but they had not been very satisfactory. He had not been able to get power enough. On his return he had undertaken rather a daring innovation. He had mingled two varieties of powder, and the resulting combination would, he hoped, prove just what he wanted.
The powder was in gelatin form, being made with nitro-glycerine as a base. It looked, as Mr. Damon had said, like a bunch of excelsior, only it was yellow instead of white, and it felt not unlike pieces of dry macaroni.
"I have shredded the powder in this manner," Tom explained, "so that it will explode more evenly and quickly. I want it to burn as nearly instantaneously as possible, and I think it will in this form."
"But how are you going to tell how powerful it is unless you fire it in a cannon?" asked Ned. "And you haven't even started your big gun yet."
"Oh, I'll show you," declared Tom. "There are several ways of making a test, but I have one of my own. I am going to take a solid block of steel, of known weight—say about a hundred pounds. This I will put into a sort of square cylinder, or well, closed at the bottom somewhat like the breech of a gun. The block of steel fits so closely in the square well that no air or powder gas can pass it.
"In the bottom of this well, which may be a foot square, I will put a small charge of this new powder. On top of that will come the steel block. Then by means of electric wires I can fire the charge.
"Attached to the steel well, or chamber, will be a gauge, a pressure recorder and other apparatus. When the powder, of which I will use only a pinch, carefully weighing it, goes off, it will raise the hundred-pound weight a certain distance. This will be noted on the scale. There will also be shown the amount of pressure released in the gas given off by the powder. In that way I can make some calculations."
"How?" asked Ned, who was much interested.
"Well, for instance, if one ounce of powder raises the weight three feet, and gives a muzzle pressure of, say, five hundred pounds, I can easily compute what a thousand pounds of powder, acting on a projectile weighing two tons and a half, would do, and how far it would shoot it."
"Bless my differential gear!" cried Mr. Damon. "A projectile weighing two and a half, tons! Tom, it's impossible!"
"That's what General Waller said about his gun; but it burst, just the same," declared Ned. "Poor man, I felt sorry for him. He seemed rather put out at you, Tom."
"I guess he was—a bit—though I didn't mean anything disrespectful in what I said. But now we'll have this test. Koku, take the rest of this powder back. I'll only keep a small quantity."
The giant, who, being more active than Eradicate, had rather supplanted the aged colored man, did as he was bid, and soon Tom, with Ned and Mr. Damon to help him, was preparing for the test.
They went some distance away from any of the buildings, for, though Tom was only going to use a small quantity of the explosive, he did not just know what the result would be, and he wanted to take no chances.
"I know from personal experience what the two kinds of powder from which I made this sample will do," he said; "but it is like taking two known quantities and getting a third unknown one from them. There is an unequal force between the two samples that may make an entirely new compound."
The steel chamber that was to receive the hundred-pound steel block had been prepared in advance, as had the various gauges and registering apparatus.
"Well, I guess we'll start things moving now," went on Tom, as he looked over the things he had brought from his shops to the deserted meadow. The fact of the test had been kept a secret, so there were no spectators. "Ned, give me a hand with this block," Tom went on. "It's a little too heavy to lift alone." He was straining and tugging at the heavy piece of steel.
"Me do!" exclaimed Koku the giant, gently pushing Tom to one side. Then the big man, with one hand, raised the hundred-pound weight as easily as if it were a loaf of bread, and deposited it where Tom wanted it.
"Thanks!" exclaimed our hero, with a laugh. "I didn't make any mistake when I brought you home with me, Koku."
"Huh! I could hab lifted dat weight when I was a young feller!" exclaimed Eradicate, who was, it is needless to say, jealous of the giant.
The powder had been put in the firing chamber. The steel socket had been firmly fixed in the earth, so that if the force of the explosion was in a lateral direction, instead of straight up, no damage would result. The weight, even if it shot from the muzzle of the improvised "cannon," would only go harmlessly up in the air, and then drop back. The firing wires were so long that Tom and his friends could stand some distance away.
"Are you all ready?" cried Tom, as he looked to see that the wiring was clear.
"As ready as we ever shall be," replied Mr. Damon, who, with Ned and the others, had taken refuge behind a low hill.
"Oh, this isn't going to be much of an explosion," laughed Tom. "It won't be any worse than a Fourth of July cannon. Here she goes!"
He pressed the electric button, there was a flash, a dull, muffled report and, for a moment, something black showed at the top of the steel chamber. Then it dropped back inside again.
"Pshaw!" cried Tom, in disappointed tones. "It didn't even blow the weight out of the tube. That powder's no good! It's a failure!"
Followed by the others, the young inventor started toward the small square "cannon." Tom wanted to read the records made by the gases.
Suddenly Koku cried:
"There him be, master! There him be!" and he pointed toward a distant path that traversed the meadow.
"He? Whom do you mean?" asked Tom, startled the giant's excited manner.
"That man what come and look at Master's new powder," was the unexpected answer. "Him say he want to surprise you, and he come today, but no speak. He run away. Look—him go!" and he pointed toward a figure of distinctly military bearing hurrying along the road that led to Shopton.