ilary's blood was boiling as the terrible narration went on and on. But his face was calm, immovable.
"How do the diskoids operate?" he asked.
"Something like the sun rays on the one-man fliers," Grim told him, "only vastly more powerful. They are not limited in range, for one thing. It took only one, fifty miles up in the stratosphere, to destroy all New York. I saw the one that first spied on the Earth. It was about five hundred feet in diameter, made of the same vitreous material, and shaped like a huge lens. No doubt, besides being a space ship, it is just that. The sun's light flashes through it, is rearranged into terrible burning rays, and sears all in its path."
"Hm'm!" Hilary meditated. "So everything the Mercutians have in the way of weapons and armament depends directly on the sun's rays."
"Yes," Grim agreed. "After all, you must remember that with Mercury exposed as it is to the fierce heat of the sun, it would be only natural for them to develop weapons that utilized its rays."
"Then the tubes and the fliers cannot operate at night?"
"Yes, because then they receive the reflected waves from the diskoids that are stationed out in space, in eternal sunlight."
Hilary considered this a moment.
"Where do you think it possible Joan was taken?" he changed the subject abruptly.