"What was that vitrilene helmet for?"

"To protect me from the effects of the black lamp."

"What is the black lamp?"

"I don't know exactly. Saranoff invented it. It gives a black light
and it kills all other light except sunlight, and it paralyses the
brain."

"Did you know that the model of the Breslau gun had been stolen?"

"Yes."

"What were you going to do after you were rescued from jail?"

"I was going to make a full-sized gun. We have a disappearing gun
platform built in the swamps at the juncture of the Potomac and
Piscataway Creek. The gun was to be mounted there and we would shell
Washington and institute a reign of terror. It would be a signal for
uprisings all over the country."

"Is there a black lamp at that gun platform?"

"Yes. The black lamp will kill both the flash and the report."

"Where did you get the formula for radite?"

"We got it from one of Dr. Bird's assistants. His name--"

* * * * *

As he spoke the last few sentences, Karuska's voice had steadily risen
almost to a shriek. As he endeavored to give the name of the doctor's
treacherous helper his voice changed to an unintelligible screech and
then died away into silence. Major Martin stepped forward and bent
over the prone figure. Hurriedly he tore away the electrical
connections and placed a stethoscope over the Russian's heart. He
listened for a moment and then straightened up, his face pale.

"I hope that the information you obtained is worth a life, Dr. Bird,"
he said, his voice trembling slightly, "because it has cost one."

"It may easily save thousands of lives. I thank you, Major, and I will
see that no blame attaches to you for your actions. I only wish that
he had lived long enough to tell me the name of my assistant who has
sold me to Saranoff. However, we'll get that information in other
ways. Carnes, telephone Lawson at Atlanta to slam O'Grady into a cell
pending investigation while I get Camp Meade on the wire and order up
a couple of tanks. We are going to attack that gun emplacement at
daybreak."

The telephone bell in the laboratory jangled sharply. Major Martin
answered it and turned to Carnes.

"You're wanted on the telephone, Mr. Carnes."

The detective stepped forward and took the transmitter.

"Carnes speaking," he said. "Yes. Oh, hello, Bolton. Yes, we have
Karuska here, or rather his body. Yes, Dr. Bird is here right now.
You've what? Great Scott, wait a minute.