changed direction. No, Carnes, old dear, the only solution that I can
see is to turn his own guns on him. If I can, before morning,
duplicate his device, we can train it on the spot where he is and
reduce him and his machine to a pinch of yellow powder."

"Can you do it, Doctor?"

"What one man's brain can device, another man's brain can duplicate.
The only question is that of time. I am confident that Saranoff will
attack Washington to-morrow. If I can do the job to-night, we may save
the city. If not--At any rate, Carnes, your job will be to see that
the President and all of the heads of the government are out of the
city by morning. The President may refuse to leave. Knowing him as I
do, I rather expect he will."

"In that case, the issue is in the hands of the gods. Now get out of
here. I want to work. Report back at daybreak with a car."

Dr. Bird turned back to his laboratory.

"He must be using a ray of some sort, possibly a radium emanation," he
muttered to himself. "That would have no wave motion and might
accomplish the result, although I would expect the exact opposite from
it. The first thing to do is to examine that powder with a
spectroscope and see if I can get a clue to the electronic
arrangement."

* * * * *

When Carnes arrived at the Bureau of Standards at dawn be rubbed his
eyes in astonishment. The buildings were lighted up and the grounds
swarmed with workmen. Before the buildings were lined up a dozen
trucks and twice that many touring cars. A cordon of police held back
the curious. Carnes' gold badge won him an entrance and he hurried up
the stairs to Dr. Bird's laboratory. The doctor's face was drawn and
haggard, but his eyes glowed with a feverish light. Workmen were
carrying down huge boxes.

"What's up, Doctor?" demanded the detective.

"Oh, you got here at last, did you? You're just in time. If you'd been
fifteen minutes later, you would have found us gone."

"Gone where?"

"Out into Maryland in an attempt to stop Saranoff in his progress
toward Washington."

"Have you found your means of combating him?"

"I hope so, although it is not what I started out to get. Did you
bring a car as I told you?"

"It's waiting below."

"Good enough. I'll go in it. Williams, are those projectors all
loaded?"

"Yes, Dr. Bird. The magnet will be ready to go in five minutes. The
electroscopes and the other light stuff are all loaded and ready to
move."