e been possibly produced? Such
questions were the most natural things in the world for Barbican and his
companions to propound to themselves, as indeed they have been to every
astronomer from the beginning of time, and probably will be to the end.

What _did_ they see? What you can see, what anybody can see on a clear
night when the Moon is full--only our friends had all the advantages of
a closer view. From _Tycho_, as a focus, radiated in all directions, as
from the head of a peeled orange, more than a hundred luminous streaks
or channels, edges raised, middle depressed--or perhaps _vice versa_,
owing to an optical illusion--some at least twelve miles wide, some
fully thirty. In certain directions they ran for a distance of at least
six hundred miles, and seemed--especially towards the west, northwest,
and north--to cover half the southern hemisphere. One of these flashes
extended as far as _Neander_ on the 40th meridian; another, curving
around so as to furrow the _Mare Nectaris_, came to an end on the chain
of the _Pyrenees_, after a course of perhaps a little more than seven
hundred miles. On the east, some of them barred with luminous network
the _Mare Nubium_ and even the _Mare Humorum_.

The most puzzling feature of these glittering streaks was that they ran
their course directly onward, apparently neither obstructed by valley,
crater, or mountain ridge however high. They all started, as said
before, from one common focus, _Tycho's_ crater. From this they
certainly all seemed to emanate. Could they be rivers of lava once
vomited from that centre by resistless volcanic agency and afterwards
crystallized into glassy rock? This idea of Herschel's, Barbican had no
hesitation in qualifying as exceedingly absurd. Rivers running in
perfectly straight lines, across plains, and _up_ as well as _down_
mountains!

"Other astronomers," he continued, "have looked on these streaks as a
peculiar kind of _moraines_, that is, long lines of erratic blocks
belched forth with mighty power at the period of _Tycho's_ own
upheaval."

"How do you like that theory, Barbican," asked the Captain.

"It's not a particle better than Herschel's," was the reply; "no
volcanic action could project rocks to a distance of six or seven
hundred miles, not to talk of laying them down so regularly that we
can't detect a break in them."

"Happy thought!" cried Ardan suddenly; "it seems to me that I can tell
the cause of these radiating streaks!"