d. "The French accent of a Greek
waiter in a fake French restaurant. In the Bronx."

"Not quite. The pronunciation was all right for French accent, but the
cadence, the way the word-sounds were strung together, was German."

The elderly man looked at the colonel keenly. "I see you're
Intelligence," he mentioned. "Think he might be somebody up your alley,
Colonel?"

The colonel shook his head. "I doubt it. There are agents of unfriendly
powers in this country--a lot of them, I'm sorry to have to say. But
they don't speak accented English, and they don't dress eccentrically.
You know there's an enemy agent in a crowd, pick out the most normally
American type in sight and you usually won't have to look further."

The train ground to a stop. A young couple with hand-luggage came in and
sat at one end of the car, waiting until other accommodations could be
found for them. After a while, it started again. I dallied over my
drink, and then got up and excused myself, saying that I wanted to turn
in early.

In the next car behind, I met the porter who had come in just before the
stop. He looked worried, and after a moment's hesitation, he spoke to
me.

"Pardon, sir. The man in the club-car who got off at Harrisburg; did you
know him?"

"Never saw him before. Why?"

"He tipped me with a dollar bill when he got off. Later, I looked
closely at it. I do not like it."

He showed it to me, and I didn't blame him. It was marked _One Dollar_,
and _United States of America_, but outside that there wasn't a thing
right about it. One side was gray, all right, but the other side was
green. The picture wasn't the right one. And there were a lot of other
things about it, some of them absolutely ludicrous. It wasn't
counterfeit--it wasn't even an imitation of a United States bill.

And then it hit me, like a bullet in the chest. Not a bill of _our_
United States. No wonder he had been so interested in whether our
scientists accepted the theory of other time dimensions and other worlds
of alternate probability!

On an impulse, I got out two ones and gave them to the porter--perfectly
good United States Bank gold-certificates.

"You'd better let me keep this," I said, trying to make it sound the way
he'd think a Federal Agent would say it. He took the bills, smiling, and
I folded his bill and put it into my vest pocket.

"Thank you, sir," he said. "I have no wish to keep it."

Some part of my mind below the level of consciousne