"The solarium is at your disposal, Doctor," he announced. "Shall I
accompany you?"

"If you wish," assented Dr. Bird as he picked up his apparatus and
strode out of the room.

In the solarium he glanced quickly around, noting the position of each
of the articles of furniture.

"I presume that the President always sleeps with his head in this
direction?" he remarked, pointing to the pillow on the disturbed bed.

The Admiral nodded assent. Dr. Bird opened the bag which he had packed
in his laboratory, took out a sheet of cardboard covered with a metallic
looking substance, and placed it on the pillow. He stepped back and
donned a pair of smoked glasses, watching it intently. Without a word he
took off the glasses and handed them to the Admiral. The Admiral donned
them and looked at the pillow. As he did so an exclamation broke from
his lips.

"That plate seems to glow," he said in an astonished voice.

* * * * *

Dr. Bird stepped forward and laid his hand on the pillow. He was wearing
a wrist watch with a radiolite dial. The substance suddenly increased
its luminescence and began to glow fiercely, long luminous streamers
seeming to come from the dial. The Doctor took away his hand and
substituted a bottle of liquid for the plate on the pillow. Immediately
the bottle began to glow with a phosphorescent light.

"What on earth is it?" gasped Carnes.

"Excitation of a radioactive fluid," replied the Doctor. "The question
is, what is exciting it. Somebody get a stepladder."

While Bolton was gone after the ladder, the Doctor took from his bag
what looked like an ordinary pane of glass.

"Take this, Carnes," he directed, "and start holding it over each of
those panes of quartz which you can reach. Stop when I tell you to."

* * * * *

The operative held the glass over each of the panes in succession, but
the Doctor, who kept his eyes covered with the smoked glasses and
fastened on the plate which he had replaced on the pillow, said nothing.
When Bolton arrived with the ladder, the process went on. One end and
most of the front of the solarium had been covered before an exclamation
from the Doctor halted the work.

"That's the one," he exclaimed. "Hold the glass there for a moment."

Hurriedly he removed the plate from the pillow and replaced the phial of
liquid. There was only a very feeble glow.

"Good enough," he cried. "Take away the glass, but