I do not desire too sharp a focus, as I wish to irradiate the entire volume of the lead wire—not merely a single point.”

The two visitors watched without comment. Their host passed the six-inch rod of lead back and forth through the point indicated by the clamp, back and forth perhaps a dozen times. Then he tossed the spool to Bohn.

“Hold it by the spool, Mr. Bohn. It will bite now.” Bohn examined the little rod, which seemed utterly unchanged.

“Well?” he said sharply.

“We will try the fluorescent screen. I will extinguish the lights”—and again the lights were dark. Bohn placed the rod of lead above the square; at once a pallid blue-white glow spread over the surface. The scratches Bohn had made were outlined in white fire, and the square shone like a little window opening on a cloudy night sky. The cold white flame rippled as he moved the rod above it.

The voice of their host sounded: “Try your diamond, Mr. Hoffman.” Hoffman slipped a ring from his finger, and held it toward the glowing square. As it approached the wire, the gem began to glow in its setting; it glistened with an icy blue fire far brighter than the square. Hoffman withdrew it, but it continued to flame with undiminished brilliance. The lights flashed on, catching the two engineers blinking down at the glowing diamond.

“It will fluoresce for some time to come,” said Edmond. “At least you may be assured that the gem is genuine; imitations will not react.” He paused. “Is there anything further?”

“We are convinced,” said Bohn shortly. “Will you explain your methods?”

“In part.” Edmond drew a cigarette from a box beside him, and passed them to the engineers. Hoffman accepted one, but Bohn shook his head and drew out his pipe. Their host exhaled a long plume of smoke.

“Obviously,” he continued, “the simplest way to break up an atom is through sympathetic vibration. The same principle as breaking a glass goblet by playing a violin above it at the proper pitch.”

“That’s an old idea,” said Hoffman, “but it never worked.”

“No; because no one has been able to produce a vibration of great enough frequency. The electrons of most substances have revolution periods measurable in millionths of a second.

“However, certain rays are known that have frequencies of this order; I refer to the so-called cosmic rays.”

“Bah!” said Bohn. “I suppose you produce cosmic rays!”

“No,” said Edmond, staring coldly at him.

“To continue: It has also been observed that lead exposed to the weather for a long period of years becomes mildly radioactive. All the fools now occupying chairs of research have attributed this to sunlight. Of course, they are wrong; it is due to the cosmic rays.

“Therefore, I have designed this reflector”—he tapped the bowl—“which brings the cosmic rays which enter this room to a focus, intensifying their effect a thousandfold. That is what starts the disintegration of the lead; once begun, the process is self-continuous.” He paused again. “Do you wish to ask any questions?”

“Yes,” said both men at once. Hoffman fell silent, and Bohn spoke, apparently somewhat subdued.

“I have always understood that cosmic rays have unparalleled penetrative power, passing far into the deepest mines, and that even gold is very transparent to them. It is generally believed that nothing will reflect them.”

“Almost nothing, Mr. Bohn. My reflector will.”

“But what material do you use?”

“Did you ever hear of neutronium, Mr. Bohn?”

“Neutronium!” both men spoke.

“That,” said Hoffman, “is die stuff that’s left after all the electrons are driven off.