sider a moment Lowell's arguments; not that it is my
intention to combat them. You must form your own conclusions. I
shall lay before you another and, as I venture to think, more
adequate hypothesis in explanation of the channels of
Schiaparelli. We learn, however, much from Lowell's book--it is
full of interest.[1]

Lowell lays a deep foundation. He begins by showing that Mars has
an atmosphere. This must be granted him till some counter
observations are made.

[1] _Mars_, by Percival Lowell (Longmans, Green & Co.), 1896,

168

It is generally accepted. What that atmosphere is, is another
matter. He certainly has made out a good case for the presence of
water as one of its constituents,

It was long known that Mars possessed white regions at his poles,
just as our Earth does. The waning of these polar snows--if indeed
they are such--with the advance of the Martian summer, had often
been observed. Lowell plots day by day this waning. It is evident
from his observations that the snowfall must be light indeed. We
see in his map the south pole turned towards us. Mars in
perihelion always turns his south pole towards the sun and
therefore towards the Earth. We see that between the dates June
3rd to August 3rd--or in two months--the polar snow had almost
completely vanished. This denotes a very scanty covering. It must
be remembered that Mars even when nearest to the sun receives but
half our supply of solar heat and light.

But other evidence exists to show that Mars probably possesses
but little water upon his surface. The dark places are not
water-covered, although they have been named as if they were,
indeed, seas and lakes. Various phenomena show this. The canals
show it. It would never do to imagine canals crossing the seas.
No great rivers are visible. There is a striking absence of
clouds. The atmosphere of Mars seems as serene as that of Venus
appears to be cloudy. Mists and clouds, however, sometime appear
to veil his face and add to the difficulty of

169

making observations near the limb of the planet. Lowell concludes
it must be a calm and serene atmosphere; probably only
one-seventh of our own in density. The normal height of the
barometer in Mars would then be but four and a half inches. This
is a pressure far less than exists on the top of the highest
terrestrial mountain. A mountain here must have an altitude of
about ten miles to possess so low a pressure on its summit. Drops
of water big eno