been instances of students slipping out after
roll call. In spite of everything, it had happened.

Therefore a new system had been inaugurated. Before roll call Martin
marched to the back of the room to the only exit and locked it.
Pocketing the key, he returned to his podium. It had been going on this
way for two years, and was now automatic.

The day watchman, making his rounds, approached this door at precisely
two thirty-four. He heard violent pounding. Along with the pounding
there was a loud, hoarse voice, gasping, "Lemme out! Lemme out!"

The watchman consulted his clock--the one he used to make a record of
his rounds--and determined that it was two thirty-four. He knew that it
was Dr. Grant's senior theoretical physics lecture period. He recalled
that a couple of years before Dr. Grant had had trouble with students
slipping out after roll call. But it occurred to him that it was hardly
possible to sneak out, even on Dr. Grant, absent-minded as he was, by
pounding on the door and shouting, "Lemme out!" in a terrified tone of
voice.

He therefore stopped and knocked on the door, calling, "What's going on
in there?"

Whoever was doing the pounding and shouting evidently didn't hear him.
Waiting no longer, the day watchman used his master key on the door.

A smallish young man, later identified as Mark Smythe, attempted to run
past him into the hall. The watchman blocked Mark's escape and looked
toward the podium in an automatic appeal to Dr. Grant.

Dr. Grant was not there. The podium was unoccupied. So were all four
hundred seats. There was, in fact, no one in room 304 except the one
terrified student.

In due course the police arrived, along with the regents. By five
o'clock it had become certain that the greatest mass disappearance of
all times had occurred, with Mark Smythe as the sole witness.

He stuck to his story through repeated detailed questionings, and in the
end the police were stuck with it.

According to Smythe, class had begun as usual. Dr. Grant had waited
until one minute after the bell had sounded, then had marched back and
locked the door, and returned to the front. He had rapidly scanned the
room to see if there were any absences, quickly called half a dozen
names he was uncertain of, and marked the attendance slip. The police
found it still resting on the table where he had placed it.

Then he had begun his lecture by remarking that they were behind
schedule and would have to catc