came slowly beside it to study the box with narrowed eyes. He
expected the metal cover would be as immovable as the others, and he
started back and caught his breath sharply as the metal raised at his
touch and the green radiance from above flashed back from within the
box in a thousand scintillant lights. Then he stooped to see the
brilliant, silvery sheen of metal wheels that moved on jeweled
bearings.

* * * * *

A mechanism of some sort--but what? he wondered. He had some knowledge
of the stream of electrons that discharged continuously from the light
above, and he knew how they could charge an electroscope that would
automatically discharge to produce motion. He nodded in
half-understanding as the fluttering gold-leaf fell and allowed a
tiny wheel to move one notch in its escapement.

"Clockworks!" he told himself--it was as near as he could come to a
name for the machine--"and it's been running here all this time....
What for, I wonder? What was it supposed to do?"

He stared again at the bell-shape towering above him, but its purpose
was beyond guessing: it was a part of the machine. His eyes came back
to the mechanism itself. There was a splinter of stone.... Garry
reached for it unthinkingly, but his hand was checked in mid-air.

The fragment was wedged beneath a tiny lever, holding it erect.
"That's the answer," Garry whispered. "The machine was left open,"--he
felt of the cover that had been dented by some heavy blow, and saw
sharp splinters of rock beneath his feet--"a rock fell from the roof,
flaked off and dropped onto the machine, and a splinter jammed this
little lever. But the machine has been ticking along...."

His fingers reached for the stone.

"Let's go!" he said, and grinned broadly at the thoughts that were in
his mind. "Let's see what the machine would have done!"

The fragment came away within his hand, and he saw the lever fall
slowly. There was motion within the case--wheels and shining spheres
that touched one upon another were spinning in gleaming circles of
silvery green--and from above he heard the first faint whisper of a
sound.

It came from the bell, and Garry drew back to stare upward. The first
soft humming of the clear bell-note was incredibly sweet. It rose in
pitch while the volume increased, till the musical note was lost in
the rising roar that resounded from walls and roof. Higher it rose; it
was a scream that was human in its agony, pr