amiliar to readers of _Gulliver's Travels_. According to Dean
Swift's hero, the astronomers on the Flying Island of Laputa had found
two tiny satellites to Mars, one of which revolved around the planet in
ten hours. The correctness of this guess is extraordinarily close,
though at best it is, of course, nothing more than a pure coincidence.

It need not be at all surprising that much uncertainty should exist with
regard to the actual condition of the surface of Mars. The circumstances
in which we are able to see that planet at the best are, indeed, hardly
sufficient to warrant us in propounding any hard and fast theories. One
of the most experienced of living observers, the American astronomer,
Professor E.E. Barnard, considers that the view we get of Mars with the
best telescope may be fairly compared with our naked eye view of the
moon. Since we have seen that a view with quite a small telescope
entirely alters our original idea of the lunar surface, a slight
magnification revealing features of whose existence we had not
previously the slightest conception, it does not seem too much to say
that a further improvement in optical power might entirely subvert the
present notions with regard to the Martian canals. Therefore, until we
get a still nearer view of these strange markings, it seems somewhat
futile to theorise. The lines which we see are perhaps, indeed, a
foreshortened and all too dim view of some type of formation entirely
novel to us, and possibly peculiar to Mars. Differences of gravity and
other conditions, such as obtain upon different planets, may perhaps
produce very diverse results. The earth, the moon, and Mars differ
greatly from one another in size, gravitation, and other such
characteristics. Mountain-ranges so far appear typical of our globe, and
ring-mountains typical of the moon. May not the so-called "canals" be
merely some special formation peculiar to Mars, though quite a natural
result of its particular conditions and of its past history?

THE ASTEROIDS (OR MINOR PLANETS)

We now come to that belt of small planets which are known by the name of
asteroids. In the general survey of the solar system given in Chapter
II., we saw how it was long ago noticed that the distances of the
planetary orbits from the sun would have presented a marked appearance
of orderly sequence, were it not for a gap between the orbits of Mars
and Jupiter where no large planet was known to circulate. The suspicion
th