"It tells us," spoke up some one, "that Alma is entirely surrounded
and covered by a great roof, which stands several miles above the
surface." [Footnote: Compare with Venus. It would seem that,
whenever a planet reached a certain age, its people will always take
steps to preserve its atmosphere; that is, provided their
civilization is high enough.]

"What is the purpose of this roof?"

"To keep in the air and moisture, which all other planets are
steadily losing. Alma is a much older planet than ours, which is why
her people are so far advanced."

Next came "close-ups" of some inhabitants. At once the doctor saw
that these were not Venusians; they had facial expressions as sour
and cynical as the typical Venusian's had been pleasant and wise.

"You will note," commented the professor very quietly, "that these
people are far from happy."

The class seemed to take it for granted; but the doctor's trained
ears instantly caught a false note in the speaker's voice. Was the
man sure of his statement?

At the same time the doctor became aware of a certain dullness in
the vision he was borrowing. Also, the speaking became much less
distinct. It occurred to him that the boy might be drowsy; and an
unmistakable nodding shortly made this certain.