His question was drowned out by cries of alarm and the sound of cracking
glass. The walls and roof were shuddering and creaking, and the concrete
floor was heaving under their feet.

[Illustration (earthquake in the lab)]

"Look out! The test stand's breaking loose!" Tom warned.

Mr. Faber and two of his men tried frantically to brace the heavy test
stand which held the telemetering device. Another engineer rushed toward
the door to see what was happening outside. Before he reached it,
another shock knocked all of them off their feet.

Electronic equipment cascaded from the wall shelves, and a heavy-duty
chain hoist came loose from its overhead track, plunging to the floor
with a terrifying crash.

"An earthquake!" Tom gasped.

Bud, meanwhile, clawed a handhold on a wire screen enclosing an air
compressor and pulled himself to his feet. But the next moment a third,
more violent tremor rocked the building, knocking him over. "The roof!
It's caving in!" he heard someone scream.

As his eyes flashed upward in panic, Bud caught a brief glimpse of the
ponderous test stand with the priceless telemeter tilting to one side.
An instant later it crashed over, pinning Mark Faber beneath it!

Bud threw up his arms to protect himself, but too late! A falling beam
caught him on the back of the head and the young flier blacked out.