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indeed, branched, leaved and, possibly, budded many times; it
never bloomed but once.
All difficulties dissolve and speculations become needless under
one condition only: that in which rationality may be inferred
directly or indirectly by our observations on some sister world
in space, This is just the evidence which in recent years has
been claimed as derived from a study of the surface of Mars. To
that planet our hope of such evidence is restricted. Our survey
in all other directions is barred by insurmountable difficulties.
Unless some meteoric record reached our Earth, revelationary of
intelligence on a perished world, our only hope of obtaining such
evidence rests on the observation of Mars' surface features. To
this subject we confine our attention in what follows.
The observations made during recent years upon the surface
features of Mars have, excusably enough, given rise to
sensational reports. We must consider under what circumstances
these observations have been made.
Mars comes into particularly favourable conditions for
observation every fifteen years. It is true that every two years
and two months we overtake him in his orbit and he is then in
"opposition." That is, the Earth is between him and the sun: he
is therefore in the opposite part of the heavens to the sun. Now
Mars' orbit is very excentric, sometimes he is 139 million miles
from the sun, and sometimes he as as much as 154 million miles
from the sun. The Earth's orbit is, by comparison, almost
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a circle. Evidently if we pass him when he is nearest to the sun
we see him at his best; not only because he is then nearest to
us, but because he is then also most brightly lit. In such
favourable oppositions we are within 35 million miles of him; if
Mars was in aphelion we would pass him at a distance of 61
million miles. Opposition occurs under the most favourable
circumstances every fifteen years. There was one in 1862, another
in 1877, one in 1892, and so on.
When Mars is 35 million miles off and we apply a telescope
magnifying 1,000 diameters, we see him as if placed 35,000 miles
off. This would be seven times nearer than we see the moon with
the naked eye. As Mars has a diameter about twice as great as
that of the moon, at such a distance he would look fourteen times
the diameter of the moon. Granting favourable conditions of
atmosphere much should be seen.
But these are just the conditions of atmosphere of which most of
the European observatories cannot boast. It is to the honour of
Schiaparelli, of Milan, that under comparatively unfavourable
conditions and with a small instrument, he so far outstripped his
contemporaries in the observation of the features of Mars that
those contemporaries received much of his early discoveries with
scepticism. Light and dark outlines and patches on the planet's
surface had indeed been mapped by others, and even a couple of
the canals sighted; but at the opposition of 1877 Schiaparelli
first mapped any considerable
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