nt of me for an instant, but when I looked again, it
was gone."

* * * * *

Dr. Bird sat forward suddenly. "What did this shadow look like?" he
asked.

"It wasn't exactly a shadow," said the guard. "It was as if a person had
passed suddenly before me so quickly that I couldn't see him. I seemed
to feel that there was someone there, but I didn't rightly _see_
anything."

"Did you notice anything of the sort?" demanded the doctor of Trier.

"I don't know," replied Trier thoughtfully. "Now that Williams has
mentioned it, I did seem to feel a breath of air or a motion as though
something had passed in front of me. I didn't think of it at the time."

"Was this shadow opaque enough to even momentarily obscure your vision?"
went on the doctor.

"Not that I am conscious of. It was just a breath of air such as a
person might cause by passing very rapidly."

"What made you ask Trier if he had the money when you turned around?"
asked the doctor of Winston.

"Say-y-y," broke in the detective. "Who the devil are you, and what do
you mean by breaking into my examination and stopping it?"

Carnes tossed a leather wallet on the table.

"There are my credentials," he said in his quiet voice. "I am chief of
one section of the United States Secret Service as you will see, and
this is Mr. Berger, my assistant. We were in the bank, engaged on a
counterfeiting case, when the robbery took place. We have had a good
deal of experience along these lines and we are merely anxious to aid
you."

Sturtevant examined Carnes' credentials carefully and returned them.

"This is a Chicago robbery," he said, "and we have had a little
experience in robberies and in apprehending robbers ourselves. I think
that we can get along without your help."

"You have had more experience with robberies than with apprehending
robbers if the papers tell the truth," said Dr. Bird with a chuckle.

* * * * *

The detective's face flushed.

"That will be enough from you, Mr. Sherlock Holmes," he said. "If you
open your mouth again, I'll arrest you as a material witness and as a
possible accomplice."

"That sounds like Chicago methods," said Carnes quietly. "Now listen to
me, Captain. My assistant and I are merely trying to assist you in this
case. If you don't desire our assistance we'll proceed along our own
lines without interfering, but in the meantime remember that this is a
National B