firing at it with very small shots one at a time. Taking the whole
series of them, Mr. Lowell very justly compares them to "a network which
triangulates the surface of the planet like a geodetic survey, into
polygons of all shapes and sizes."

At the very lowest estimate the total length of the canals observed and
mapped by Mr. Lowell must be over a hundred thousand miles, while he
assures us that numbers of others have been seen over the whole surface,
but so faintly or on such rare occasions as to elude all attempts to fix
their position with certainty. But these, being of the same character
and evidently forming part of the same system, must also be artificial,
and thus we are led to a system of irrigation of almost unimaginable
magnitude on a planet which has no mountains, no rivers, and no rain to
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.