The gun was sighted through a small tube with an illuminated “eye” at its extremity. Through this tube it was possible to see outside the metal walls of the diving boat, and to sight the object to be aimed at in the glow cast from the searchlights in the observation tube.
Many times during the weeks of work on the White Shark Tom had experimented with the gun, and now there was no hesitation in his manner as he placed an explosive shell within the breech of the gun and closed it. This done he sighted the weapon carefully and then, with compressed lips and grim, determined manner he pressed the lever that admitted the water to the superheated chamber.
A small wheel was then turned which closed the water chamber. When it had been thus sealed, Tom’s next act was to press the button which set the electric current to its work of turning the water into superheated steam.
“One! two!” he counted, and then, with a quick nod as of assurance that he would succeed, he bent over the gun and suddenly twisted a small handle.
There was not a sound, but every one standing in the chamber knew that the gun had been fired. It was almost uncanny, this idea of releasing a giant force without there being the faintest sound to show that the projectile had sped on its way through the water.
Following the discharge of the gun came a moment of intense anxiety, and then a cry from the inventor:
“Hurray! It’s succeeded!”
“Good shot, my boy!” cried Mr. Chadwick.
Peering through the observation tube, they had seen the snake-like line of the rope part as the projectile struck it and exploded, turning the water all about into thick white obscurity. This condition lasted only an instant after the explosion. It then became clear that the White Shark was once more free.
Jack and Tom scampered to the engine room as soon as they saw that the dangling rope no longer menaced the safety of the ship.