Post Office Department, "and headed toward
Philipsburg. He never arrived. By ten we were alarmed and by eleven we
had planes out searching for him. They reported nothing. He must have
come to grief within a rather restricted area, so we sent search
parties out at once. That was two weeks ago yesterday. No trace of
either him or his plane has been found."

"The flying conditions were good?"

"Perfect. Also, Purdy is above suspicion. He has been flying the mail
on the western runs for three years. This is his first accident. He
was carrying nothing of unusual value."

"Are there any local conditions unfavorable to flying?"

"None at all. It is much uninhabited country, but there is no reason
why it shouldn't be safe country to fly over."

"There are some damnably unfavorable local conditions, Doctor,
although I can't tell you what they are," broke in Operative Carnes of
the United States Secret Service. "Dick Purdy was rather more than an
acquaintance of mine. After he was lost I looked into the record of
that section a little. It is known among aviators as 'The Port of
Missing Planes.'"

"How did it get a name like that?"

"From the number of unexplained and unexplainable accidents that
happen right there. Dugan of the air mail, was lost there last May.
They found the mailbags where he had dropped them before he crashed,
but they never found a trace of him or his plane."

"They didn't?"

"Not a trace. The same thing happened when Mayfield cracked in August.
He made a jump and broke his neck in landing. He was found all right,
but his ship wasn't. Trierson of the army, dropped there and _his_
plane was never found. Neither was he. He was seen to go down in a
forced landing. He was flying last in a formation. As soon as he went
down the other ships turned back and circled over the ground where he
should have fallen. They saw nothing. Search parties found no trace of
either him or his ship. Those are the best known cases, but I have
heard rumors of several private ships which have gone down in that
district and have never been seen or heard of since."

* * * * *

Dr. Bird sat forward with a glitter in his piercing black eyes. Carnes
gave a grunt of satisfaction. He knew the meaning of that glitter. The
Doctor's interest had been fully aroused.

"Inspector Dolan," said Dr. Bird sharply, "why didn't you tell me
those things?"

"Well, Doctor, we don't like to talk about mail wrec