"It's a piece of glass on which a thin film of platinum has been deposited. It lets light through in one direction, but not in the other. Evelyn suggested that Varrhus had something which did the same thing with heat. It would let heat through in one direction, but not in the other. Of course if it would take all the heat from the air on one side and wouldn't let any come back from the other——"
"It would be cold?"
"On one side. The glass looks black because it lets the light go through and lets none come back. The surface, we have assumed, would be almost infinitely cold because it would let heat go through and would let none come back. We decided that Varrhus had made a hollow bomb of some shape or other, composed of this hypothetical material. Heat from the outside would be radiated into the interior because the surface absorbed heat like this glass absorbs light. It would act as a surface at more than a thousand below zero. Because something had to be done with the heat that would come in, Varrhus made the bomb hollow and left two openings in it. The inside of the bomb is intensely hot from the heat that has been taken out of the surrounding water. The hole at the bottom radiates a beam of heat straight downward which melts a very small quantity of ice and lets the water flow into the bomb, where it is turned into steam. Naturally, it flows out of the other hole at the top. There you have the whole thing."
"And you stopped it——"
"By dropping a T. N. T. bomb down the steam shaft. It went off and blew the cold bomb to bits. The iceberg will break up and melt now."
The reporter stood up.
"I'd like to thank you for this, but it's too big," he said feverishly. "Man, just wait till I wave this before the city editor's eyes!" He rushed out of the house.
The newspapers that afternoon had frantic headlines announcing the destruction of the steam plume and the fact that noticeable signs of melting had begun to show themselves on the ice cake. Smaller captions told of the dynamiting that had begun and of the destruction of the Yokohama and Folkestone bergs by soldiers acting on cabled instructions. The Straits of Gibraltar were cleared by salvos fired from the heavy guns on the Rock at the three great plumes of steam. The world congratulated itself on the speedy nullification of the menace to its democratic governments. It did not neglect, however, to rush detachments of men with trench mortars and hand bombs to its reservoirs, prepared to destroy any possible cold bombs on their first appearance. The aviation forces, too, made themselves ready to fight the black flyer on its next appearance, despite the mysterious means by which it had killed the American pilot.
This state of affairs lasted for possibly a week, when, within three hours of each other, the papers found two occasions to issue extras. The first extra announced the death by heart failure of Professor Hawkins, who had been found by his daughter, dead in his laboratory, holding in his hands an antique silver bracelet he had just opened at the clasp. The second, three hours later, announced the formation of an ice cake in the Narrows which grew in size even more rapidly than the original one, and was entirely unattended by the steam plume which gave Teddy Gerrod an opportunity to destroy the first. Within three hours the Narrows were closed, and the ice floe was creeping up toward New York.
In rapid succession came the news that Norfolk harbor was frozen over and Hampton Roads closed, that Charleston was blocked, then Jacksonville. The next morning delayed cablegrams declared that the Panama Canal was a mass of ice, and almost simultaneously the Straits of Gibraltar were again admitted to be firmly locked.