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.