im suddenly to
close it and lift his head. At first he thought that he had reached the
fabulous region of eternal fire, but this he knew to be absurd; and,
besides, the light was not that of fire or heated substances. It was
pale, colorless; and although dazzling at first, he found, when very
cautiously he applied his eye again to the telescope, that it was not
blinding. In fact, he could look at it as steadily as he could upon a
clear sky.

But, gaze as he would, he could see nothing--nothing but light; subdued,
soft, beautiful light. He knew the ray was passing steadily downward,
for the mechanism was working with its accustomed regularity, but it
revealed to him nothing at all. He could not understand it; his brain
was dazed. He thought there might be something the matter with his
eyesight. He got down from the ladder and hurriedly sent for Margaret,
and when she came he begged her to look through the telescope and tell
him what she saw. She went inside the screen, ascended the ladder, and
looked down.

"It isn't anything," she called out presently. "It looks like lighter
air; it can't be that. Perhaps there is something the matter with your
telescope."

Clewe had thought of that, and as soon as she came out he examined the
instrument, but the lenses were all right. There was nothing the matter
with the telescope.

That night Roland Clewe spent in the lens-house, almost constantly at
the telescope, but nothing did he see but a disk of soft, white light.

"The world can't be hollow!" he said to Margaret the next morning. "It
can't be filled with air, or nothing, and my ray would not illuminate
air or nothing. I cannot understand it. If you did not see what I see, I
should think I was going crazy."

"Don't talk that way," exclaimed Margaret. "This may be some cavity
which the ray will soon pass through, and then we shall come to the good
old familiar rock again."

But Clewe could not be consoled in this way. He could see no reason why
his ray acting upon the emptiness of a cavern should produce the effect
he beheld. Moreover, if the ray had revealed a cavern of considerable
extent he could not expect that it could now pass through it, for the
limit of its operations was almost reached. His electric cumulators
would cease to act in a few hours more. The ray had now descended more
than fourteen miles--its limit was fifteen.

Margaret was greatly troubled because of the effect of this result of
the light borer