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?"

"Oh dear, no," exclaimed the astronomer, smiling incredulously. "The
idea of signalling has got into people's heads through the outcry raised
about it some time ago, when Mars was in 'opposition' and near the
earth. I suppose you are thinking of the plan for raising and lowering
the lights of London to attract the notice of the Martians?"

"No; I believe I told you of the singular experience I had some five or
six years ago with an old astronomer, who thought he had established an
optical telegraph to Mars?"

"Oh, yes, I remember now. Ah, that poor old chap was insane. Like the
astronomer in _Rasselas_, he had brooded so long in solitude over his
visionary idea that he had come to imagine it a reality."

"Might there not be some truth in his notion? Perhaps he was only a
little before his time."

Gazen shook his head.

"You see," he replied, "Mars is a much older planet than ours. In winter
the Arctic snows extend to within forty degrees of the equator, and the
climate must be very cold. If human beings ever existed on it they must
have died out long ago, or sunk to the condition of the Eskimo."

"May not the climate be softened by conditions of land and sea unknown
to us? May not the science and civilisation of the Martians enable them
to cope with the low temperature?"

"The atmosphere of Mars is as rare as ours at a height of six miles, and
a warm-blooded creature like man would expire in it."

"Like man, yes," I answered; "but man was made for this world. We are
too apt to measure things by our own experience. Why should we limit the
potentiality of life by what we know of this planet?"

"In the next place," went on Gazen, ignoring my remark, "the old
astronomer's plan of signalling by strong lights was quite
impracticable. No artificial light is capable of reaching to Mars. Think
of the immense distance and the two atmospheres to penetrate! The man
was mad, as mad as a March hare! though why a March hare is mad I'm sure
I don't know."

"I read the other day of an electric light in America which can be