"Say that again," said Ardan. "I want Mac to hear it."

Barbican humored him by repeating the observation, but M'Nicholl would
only notice it by a grunt of doubtful meaning.

"Was Galileo tolerably successful in his calculations?" asked Ardan,
resuming the conversation.

Before answering this question, Barbican unrolled the map of the Moon,
which a faint light like that of day-break now enabled him to examine.
He then went on: "Galileo was wonderfully successful--considering that
the telescope which he employed was a poor instrument of his own
construction, magnifying only thirty times. He gave the lunar mountains
a height of about 26,000 feet--an altitude cut down by Hevelius, but
almost doubled by Riccioli. Herschel was the first to come pretty close
to the truth, but Beer and Maedler, whose _Mappa Selenographica_ now
lies before us, have left really nothing more to be done for lunar
astronomy--except, of course, to pay a personal visit to the
Moon--which we have tried to do, but I fear with a very poor prospect of
success."

"Cheer up! cheer up!" cried Ardan. "It's not all over yet by long odds.
Who can say what is still in store for us? Another bolide may shunt us
off our ellipse and even send us to the Moon's surface."

Then seeing Barbican shake his head ominously and his countenance become
more and more depressed, this true friend tried to brighten him up a bit
by feigning to take deep interest in a subject that to him was
absolutely the driest in the world.

"Meer and Baedler--I mean Beer and Maedler," he went on, "must have
measured at least forty or fifty mountains to their satisfaction."

"Forty or fifty!" exclaimed Barbican. "They measured no fewer than a
thousand and ninety-five lunar mountains and crater summits with a
perfect success. Six of these reach an altitude of upwards of 18,000
feet, and twenty-two are more than 15,000 feet high."

"Which is the highest in the lot?" asked Ardan, keenly relishing
Barbican's earnestness.

"_Doerfel_ in the southern hemisphere, the peak of which I have just
pointed out, is the highest of the lunar mountains so far measured,"
replied Barbican. "It is nearly 25,000 feet high."

"Indeed! Five thousand feet lower than Mount Everest--still for a lunar
mountain, it is quite a respectable altitude."

"Respectable! Why it's an enormous altitude, my dear friend, if you
compare it with the Moon's diameter. The Earth's diameter being more
than 3-1/2 times great