o
support it; whose whole water-supply is derived from polar snows, the
amount of which is ludicrously inadequate to need any such world-wide
system; while the low atmospheric pressure would lead to rapid
evaporation, thus greatly diminishing the small amount of moisture that
is available. Everyone must, I think, agree with Miss Clerke, that, even
admitting the assumption that the polar snows consist of frozen water,
the excessively scanty amount of water thus obtained would render any
scheme of world-wide distribution of it hopelessly unworkable.

The very remarkable phenomena of the duplication of many of the lines,
together with the darkspots--the so-called oases--at their
intersections, are doubtless all connected in some unknown way with the
constitution and past history of the planet; but, on the theory of the
whole being works of art, they certainly do _not_ help to remove any of
the difficulties which have been shown to attend the theory that the
single lines represent artificial canals of irrigation with a strip of
verdure on each side of them produced by their overflow.

_Lowell on the Purpose of the Canals._

Before leaving this subject it will be well to quote Mr. Lowell's own
words as to the supposed perfectly level surface of Mars, and his
interpretation of the origin and purpose of the 'canals':

"A body of planetary size, if unrotating, becomes a sphere, except for
solar tidal deformation; if rotating, it takes on a spheroidal form
exactly expressive, so far as observation goes, of the so-called
centrifugal force at work. Mars presents such a figure, being flattened
out to correspond to its axial rotation. Its surface therefore is in
fluid equilibrium, or, in other words, a particle of liquid at any point
of its surface at the present time would stay where it was devoid of
inclination to move elsewhere. Now the water which quickens the verdure
of the canals moves from the pole down to the equator as the season
advances. This it does then irrespective of gravity. No natural force
propels it, and the inference is forthright and inevitable that it is
artificially helped to its end. There seems to be no escape from this
deduction. Water only flows downhill, and there is no such thing as
downhill on a surface already in fluid equilibrium. A few canals might
presumably be so situated that their flow could, by inequality of
terrane, lie equatorward, but not all....Now it is not in particular but
by general