“Cheerful chap you are,” said Elstead, and spat sociably at a bubble below.
“I don’t understand yet how you mean to work the thing,” said Steevens.
“In the first place I’m screwed into the sphere,” said Elstead, “and when I’ve turned the electric light off and on three times to show I’m cheerful, I’m swung out over the stern by that crane, with all those big lead sinkers slung below me. The top lead weight has a roller carrying a hundred fathoms of strong cord rolled up, and that’s all that joins the sinkers to the sphere, except the slings that will be cut when the affair is dropped. We use cord rather than wire rope because it’s easier to cut and more buoyant—necessary points as you will see.
“Through each of these lead weights you notice there is a hole, and an iron rod will be run through that and will project six feet on the lower side. If that rod is rammed up from below it knocks up a lever and sets the clockwork in motion at the side of the cylinder on which the cord winds.
“Very well. The whole affair is lowered gently into the water, and the slings are cut. The sphere floats—with the air in it, it’s lighter than water; but the lead weights go down straight and the cord runs out. When the cord is all paid out, the sphere will go down too, pulled down by the cord.”
“But why the cord?” asked Steevens. “Why not fasten the weights directly to the sphere?”
“Because of the smash down below. The whole affair will go rushing down, mile after mile, at a headlong pace at last. It would be knocked to pieces on the bottom if it wasn’t for that cord. But the weights will hit the bottom, and directly they do the buoyancy of the sphere will come into play. It will go on sinking slower and slower; come to a stop at last and then begin to float upward again.
“That’s where the clockwork comes in. Directly the weights smash against the sea bottom, the rod will be knocked through and will kick up the clockwork, and the cord will be rewound on the reel. I shall be lugged down to the sea bottom. There I shall stay for half an hour, with the electric light on, looking about me. Then the clockwork will release a spring knife, the cord will be cut, and up I shall rush again, like a soda-water bubble. The cord itself will help the flotation.”
“And if you should chance to hit a ship?” said Weybridge.
“I should come up at such a pace, I should go clean through it,” said Elstead, “like a cannon ball. You needn’t worry about that.”