t on the other side of the Earth, and a gradually appearing
umbrella shape there too."

"Ah, then you steered far enough out of your course to see part of the
illuminated surface of the Earth. That was the real danger light. And if
it began to assume the umbrella shape, detached from the Earth, that was
due to atmospheric refraction of sunlight. This great shadow we are
travelling in has an illuminated core, which we shall encounter when we
have proceeded a little further. I tell you of it now, so it may not
give you another shock. Have you ever noticed the small bright spot
which illuminates the centre of the shadow cast by a glass of water?
That is partly the same as the core of light which exists in the heart
of this shadow. Rays from the sun, passing on all sides of the Earth,
are refracted through the atmosphere and bent inward. You must have
steered over into some of these rays just now, and then turned back from
them. Somewhat farther on all these refracted rays will meet at a common
centre, which they will illuminate, and we shall have an oasis of
rainbow-tinged sunlight in this great desert of shadow. The sun will
then appear to us to be an enormous circle of dull light entirely
surrounding the Earth."

"I don't fancy running into that at all," said I. "Can't we avoid it by
steering out?"

"Avoid it!" exclaimed the doctor. "We must investigate it, and
photograph the peculiar appearance of the sun. Light seems to have more
terrors for you than anything else just now. You must get over your
rush-and-do tendency; you must stifle your emotions and impulses, and
learn to think of things in a more calm and scientific manner."

"But that is not so easy for me, Doctor. Whenever I am left alone, a
feeling of dread possesses me. I am used to having many people, bustling
noises, and confused movement all about me. The silence of Space stifles
me, and the loneliness of the ether oppresses and overcomes me
strangely."

"I prescribe a change of air for you," answered the doctor. "You will do
better in a rarer atmosphere. Let us send what we have been breathing
back to Whiting, and make a new one to suit ourselves."

CHAPTER X

The Twilight of Space

"Shall I come up into your compartment for the operation?" I asked.

"No; for this first time we will pump out my compartment, as I wish to
observe from the rear port-hole the action of the air which we set
free."

The bulkhead, with its bevelled edge, was th