"Don't mention it," he replied cordially; "I'm observing one of the
nebulas just now, but it won't be in sight for a long time yet."

"What about this mysterious light on Mars. Have you seen anything of
it?"

Gazen laughed.

"I have not," said he, "though I did look the other night."

"You believe that something of the kind has been seen?"

"Oh, certainly. The Nice Observatory, of which Monsieur Perrotin is
director, has one of the finest telescopes in existence, and Monsieur
Javelle is well-known for his careful work."

"How do you account for it?"

"The light is not outside the disc," responded Gazen, "else I should
ascribe it to a small comet. It may be due to an aurora in Mars as a
writer in _Nature_ has suggested, or to a range of snowy Alps, or even
to a bright cloud, reflecting the sunrise. Possibly the Martians have
seen the forest fires in America, and started a rival illumination."

"What strikes you as the likeliest of these notions?"

"Mountain peaks catching the sunshine."

"Might it not be the glare of a city, or a powerful search-light--in
short, a signal?"