“But Bernstine or his clerk will hear of the matter sooner or later,” complained Pendleton.  “And the police and reporters will then get in on the thing anyhow.”

“But there will be a delay,” said his friend.  “And that may be what we need just now.  Perhaps a few hours will mean success.  You can never tell.  The best that we could get by explaining matters to Sime would be a positive identification of Spatola, or the reverse.  And we can get that from him at any time.  So you see, we lose nothing by waiting.”

“I guess that’s so,” Pendleton acknowledged, and again the car started forward.  At the huge entrance to a railroad station they drew up once more.

Within, Ashton-Kirk inquired for the General Passenger Agent and was directed to the ninth floor.  The agent was a slim little man with huge whiskers of snowy whiteness, and a most dignified manner.

“Oh, yes,” he said, after glancing at the investigator’s card.  “I have heard of you, of course.  Who,” with a little bow, “has not?  Indeed, if I remember aright, this road had the honor to employ you a few years ago in a matter necessitating some little delicacy of handling.  Am I not right?”

“And I think it was you,” said Ashton-Kirk, smoothly, “who provided me with some very clearly cut facts which were of considerable service.”

The little General Passenger Agent looked pleased and smoothed his beautiful whiskers softly.

“I was most happy,” said he.

“Just now,” said Ashton-Kirk, “I am engaged in a matter of some consequence, and once more you can be of assistance to me.”

“Sit down,” invited the other, readily.  “Sit down, and command me.”

Both Pendleton and the investigator sat down.  The latter said to the passenger agent: 

“I understand that every railroad has a system by which it can tell which conductor has punched a ticket.”

“Oh, yes.  A very simple one.  You see the hole left by each punch is different.  One will cut a perfectly round hole, another will be square, still another will be a triangle, and so on, indefinitely.”

From his card case, Ashton-Kirk produced the small red particle which he had found upon the desk of the murdered man.

“Here is a fragment cut from a ticket,” he said.  “It is shaped like a keystone.  I should like to know, if you can tell me, what train is taken out by the conductor who uses the keystone punch.”

The agent touched a signal and picked up the end of a tube.

“The head ticket counter,” said he.  “At once.”  Then he laid down the tube and continued to his visitors.  “He is the man who can supply that sort of information instantly.”

The ticket counter was a heavy-set young man, in spectacles and with his hair much rumpled.  He peered curiously at the strangers.

“Does any conductor on our lines use a punch which cuts out a keystone?” inquired the General Passenger Agent.