ing by. When do you expect trouble?"

"I have no idea. It may come to-night or it may come later. Personally
I hope that it comes later so that we can get in a few days of fishing
before anything happens."

"What do you expect to happen, Doctor?" demanded Carnes. "Every time I
have asked you anything you told me to wait until we were in the
Maine woods and we are there now. I read up everything that I could
find on amnesia victims during the past three months but it didn't
throw much light on the matter to me."

"How many cases did you find, Carnes?"

"Sixteen. There may have been lots more but I couldn't find any others
in the _Post_ records. Of course, unless the victim were a local man,
or of some prominence, it wouldn't appear."

"You got most of them at that. Did any points of similarity strike you
as you read them?"

"None except that all were prominent men and all of them mental
workers of high caliber. That didn't appear peculiar because it is the
man of high mentality who is most apt to crack."

"Undoubtedly. There were some points of similarity which you missed.
Where did the attacks take place?"

"Why, one was at--Thunder, Doctor! I did miss something. Every case,
as nearly as I can recall, happened at some summer camp or other
resort where they were on vacation."

"Correct. One other point. At what time of day did they occur?"

"In the morning, as well as I can remember. That point didn't
register."

"They were all discovered in the morning, Carnes, which means that the
actual loss of memory occurred during the night. Further, every case
has happened within a circle with a diameter of three hundred miles.
We are near the northern edge of that circle."

* * * * *

Carnes checked up on his memory rapidly.

"You're right, Doctor," he cried. "Do you think--?"

"Once in a while," replied Dr. Bird dryly, "I think enough to know the
futility of guesses hazarded without complete data. We are now located
within the limits of the amnesia belt and we are here to find out what
did happen, if anything, and not to make wild guesses about it. You
have the tent set up for us, Major?"

"Yes, Doctor, about thirty yards from the cabin and hidden so well
that you could pass it a dozen times a day without suspecting its
existence. The gas masks and other equipment which you sent to Fort
Banks are in it."

"In that case we had better dispense with your company as soon as we
ha