wer, sheerer, and in places they had
to straddle it, legs dangling precariously to left and right.

Admiration for his gallant companion mounted in the professor's
pounding heart, as they struggled on. Only to picture anyone eager to
return such a perilous way, after once getting safely back!

Other thoughts occupied his mind, too, during the next half-hour. More
than once he could have sworn he saw small, ghostly figures on the
ridge ahead. But he made no mention of it, for Stoddard didn't seem to
see them.

Now they gained the far end of that hazardous ridge, where a sloping
shelf of jagged rock offered a somewhat more secure footing. Along
this they proceeded laterally for some distance.

Suddenly Stoddard paused and called out:

"Ah--there we are!" He indicated a steep pocket to the left. "Have a
look down there, Professor, and tell me what you see."

* * * * *

Prescott lowered his eyes to the depths below, to draw back with a
gasp--for what he saw was a vast phosphorescent glow, like a fallen
star.

"What--what is it?" he cried, in an awed voice.

And back came the ringing reply:

"The Diamond Thunderbolt!"

"But the radiance of the thing! It couldn't reflect that much light
from the moon!"

"No, and it doesn't. But there's nothing uncanny about it. Just what I
expected the thing would look like at night. But come on, Professor.
You haven't seen the half of it!"

The way led down the jagged, shelving slope, now, and the descent was
too precarious for further comment.

Ten minutes passed--fifteen, possibly--when they reached a sheltered,
snowless arena where titanic forces had clashed at some remote age.
Fragments of splintered rock lay strewn in wild confusion--and among
them, glinting in the moonlight, were bright crystals.

Picking up one, Stoddard said laughingly:

"One of Mother Nature's trinkets worth half a million or so!"

Professor Prescott blinked at it a moment, almost in disbelief, then
stooped and picked up one for himself--a diamond that would have made
the Kohinoor look like a pebble.

There was no doubting its genuineness. Even in the moonlight, it
flashed and burned like a thing afire.

But as the professor turned his eyes at last from its dazzling facets,
they failed him again--or so he thought--for half hidden behind a
jutting crag loomed a huge cylindrical object, seemingly of metal.

* * * * *

For the spa