een sabotaged. But that wasn't all. Etched on the bar was a rather
good picture of a knight in armor, in the process of driving his sword
through a rocket. Underneath was the inscription: _Homo Terrestrialis_."

[Illustration: _Etched on the bar was a puzzling inscription_]

"I don't get it," Rick complained.

Gordon grinned. "Neither did we. And we still don't get it. But you can
be sure we started a few balls rolling. First, Security checked every
man's file again. They missed no one. Even the security officers and
guards were rechecked. Then they started a program to find out who on
the base had any talent as an artist. Nothing was found. The security
chief sent photos of the etched picture and the whole bar mechanism to
every security agency in the government, including the FBI, Central
Intelligence, and the military. He drew a blank. No one had ever heard
of anyone calling himself the Earthman, and the technique wasn't
familiar."

The scientist paused long enough to eat a little more, then resumed.

"Meanwhile, we were getting a Viking rocket ready to launch. We checked
it from nose to fins. We didn't miss a thing. Then we posted a guard
around it, and a guard to watch the guard. We took no chances at all.
The project engineer even slept near the rocket where he could keep an
eye on it."

"Did anyone climb the tower?" Barby asked.

"There was no tower. A Viking rests on its fins. Anyway, it took off. It
climbed ten miles, then went on an erratic course. We couldn't control
it. Fortunately it crashed on the Las Vegas Bombing and Gunnery Range,
which is a closed military area nearby, so no one was hurt. At first we
thought it was just one of those typical accidents that happen during
rocket research. Even the best-performing rockets sometimes go haywire.
But when we got into the wreckage, we found the steering vanes had been
tampered with, in a way that inspection couldn't have disclosed."

"Was there a picture?" Scotty asked.

"Not in or on the rocket. But when we got back to the base after
inspecting it, everyone was excited. Someone had sketched a knight in
armor with crayon right on the concrete of the launching pad."

Rick said thoughtfully, "Then you can eliminate those who went to
inspect the crashed Viking."

"Unfortunately, no. We have no way of telling when the picture was
drawn. No one was seen near the launching pad between the time the
rocket was fired and the discovery of the sketch on our r