Telescopic aspect of the planet Mars (Feb.,
1901).]

As to the "seas," it is pretty certain that there must be water, or
some kind of liquid, deriving above all from the melting of the polar
snows in spring and summer; but it may possibly be in conjunction with
some vegetation, aquatic plants, or perhaps vast meadows, which appear
to us from here to be the more considerable in proportion as the water
that nourishes them has been more abundant.

[Illustration: FIG. 42.--Telescopic aspect of the planet Mars (Feb.,
1901).]

Mars, like our globe, is surrounded with a protective atmosphere, which
retains the rays of the Sun, and must preserve a medium temperature
favorable to the conservation of life upon the surface of the planet.
But the circulation of the water, so important to terrestrial life,
whether animal or vegetable, which is effected upon our planet by the
evaporation of the seas, clouds, winds, rains, wells, rivers and
streams, comes about quite differently on Mars; for, as was remarked
above, it is rarely that any clouds are observed there. Instead of being
vertical, as here, this circulation is horizontal: the water coming from
the source of the polar snows finds its way into the canals and seas,
and returns to be condensed at the poles by a light drift of invisible
vapors directed from the equator to the poles. There is never any rain.

We have spoken of _canals_. One of the great puzzles of the Martian
world is incontestably the appearance of straight lines that furrow its
surface in all directions, and seem to connect the seas. M.
Schiaparelli, the distinguished Director of the Observatory of Milan,
who discovered them in 1877, called them canals, without, however,
postulating anything as to their real nature. Are they indeed canals?
These straight lines, measuring sometimes 600 kilometers (372 miles) in
length, and more than 100 kilometers (62 miles) in breadth, have much
the same hue as the seas on which they open. For a quarter of a century
they have been surveyed by the greater number of our observers. But it
must be confessed that, even with the best instruments, we only approach
Mars at a distance of 60,000 kilometers (37,200 miles), which is still a
little far off, and we may be sure that we do not distinguish the true
details of the surface.[11] These details at the limits of visibility
produce the appearance of canals to our eyes. They may possibly be lines
of lakes, or oases. The future will no