THE CANALS OF MARS
Both of the two worlds best placed for our study are thus, for different
reasons, ruled out of court as worlds for habitation. The Sun by its
vastness, its intolerable heat and the violence of its changes, has to be
rejected on the one hand, while the Moon, so small, and therefore so
rigid, unchanging and bare, is rejected on the other.
Of the other heavenly bodies, the planet Mars is the one that we see to
best advantage. Two other planets, Eros and Venus, at times come nearer to
us, but neither offers us on such occasions equal facilities for their
examination. But of Mars it has been asserted not only that it is
inhabited, but that we know it to be the case, since the evidence of the
handiwork of intelligent beings is manifest to us, even across the
tremendous gulf of forty or more million miles of space.
A claim so remarkable almost captures the position by its audacity. There
is a natural desire among men to believe the marvellous, and the very
boldness of the assertion goes no small way to overcome incredulity. And
when we consider how puny are men as we see them on this our planet, how
minute their greatest works, how superhuman any undertaking would be which
could demonstrate our existence to observers on another planet, we must
admit that it is a marvel that there should be any evidence forthcoming
that could bear one way or another on the solution of a problem so
difficult.
The first fact that we have to remember with regard to the planet Mars is
the smallness of its apparent size. To the eye it is nearly a star--a
point of light without visible surface. It is almost twice the size of the
Moon in actual diameter, but as its mean distance from the Earth is 600
times that of the Moon, its mean apparent diameter is 300 times smaller.
We cannot, however, watch Mars in all parts of its orbit; it is best
placed for observation, and, therefore, most observed, when in opposition,
and oppositions may be favourable or unfavourable. At the most favourable
opposition, Mars is 140 times as distant as the Moon; at the least
favourable, 260 times; so that on such occasions its apparent size varies
from 1/70th of the diameter of the Moon to 1/130th. But a telescope with a
magnifying power of 70 could never, under the most perfect conditions,
show Mars, even in the closest opposition, as well as the Moon is seen
with the naked eye, for the practical magnifying power of a telescope is
never as great as the theoretical. In practice, a child's spy-glass
magnifying some six diameters will show the full Moon to better advantage
than Mars has ever been seen, even in our most powerful telescopes.
The small apparent size of the planet explains how it was that Galileo
does not seem to have been able to detect any markings upon it. In 1659,
Huyghens laid the foundation stone of areography by observing some dark
spots, and determining from their apparent movements that the planet had a
rotation on its axis, which it accomplished in about the same time as the
Earth. Small and rough as are the drawings that Huyghens made, the
identification of one or two of his spots is unmistakable. Seven years
later, in 1666, both Cassini and Hooke made a number of sketches, and
those by Hooke have been repeatedly used in modern determinations of the
rotation period of the planet. The next great advance was made by Sir
William Herschel, who, during the oppositions of 1777, 1779, 1781, and
1783, determined the inclination of the axis of Mars to the plane of its
orbit, measured its polar and equatorial diameters, and ascertained the
amount of the polar flattening. He paid also special attention to two
bright white spots upon the planet, and he showed that these formed round
the planet's poles and increased in size as the winter of each several
hemisphere drew on and diminished again with the advance of summer,
behaving therefore as do the snow caps of our own polar regions.
The next stage in the development of our knowledge of Mars must be
ascribed to the two German astronomers, Beer and Maedler, who made a series
of drawings in the years 1830, 1832 and 1837, by means of a telescope of 4
inches aperture, from which they were able to construct a chart of the
entire globe. This chart may be considered classic, for the features which
it represents have been observed afresh at each succeeding opposition.
Mars, therefore, possesses a permanent topography, and some of the
markings in question can be identified, not only in the rough sketches
made by Sir William Herschel, but even in those made by Hooke and Cassini
as far back as the year 1666. In the forty years that followed, the planet
was studied by many of the most skilled observers, particularly by Mr. J.
N. Lockyer in 1862, and the Rev. W. R. Dawes in 1864. In 1877, the late
Mr. N. E. Green, drawing-master to Queen Victoria, and a distinguished
painter in water colours, made a series of sketches of the planet from a
station in the island of Madeira 2000 feet above sea-level. When the
opposition was over, Mr. Green collected together a large number of
drawings, and formed a chart of the planet, much richer in detail than any
that had preceded it, and from his skill, experience and training as an
artist he reproduced the appearance of the planet with a fidelity that had
never been equalled before and has never been surpassed since. At this
time it was generally assumed that Mars was a miniature of our own world.
The brighter districts of its surface were supposed to be continents, the
darker, seas. As Sir William Herschel had already pointed out long before,
the little world evidently had its seasons, its axis being inclined to the
plane of its orbit at much the same angle as is the case with the Earth;
it had its polar caps, presumably of ice and snow; its day was but very
little longer than that of the Earth; and the only important difference
seemed to be that it had a longer year, and was a little further off the
Sun. But the general conclusion was that it was so like the Earth in its
conditions that we had practically found out all that there was to know;
all that seemed to be reserved for future research was that a few minor
details of the surface might be filled in as the power of our telescopes
was increased.
But fortunately for progress, this sense of satisfaction was to be rudely
disturbed. As Mars, in its progress round the Sun, receded from the Earth,
or rather as the Earth moved away from it, the astronomers who observed so
diligently during the autumn of 1877 turned their attention to other
objects. One of them, however, Schiaparelli, the most distinguished
astronomer on the continent of Europe, still continued to watch the
planet, and, as the result of his labours, he published some months later
the first of a magnificent series of _Memoirs_, bringing to light what
appeared to be a new feature. His drawings not only showed the "lands" and
"seas," that is to say the bright and dark areas, that Green and his
predecessors had drawn, but also a number of fine, narrow, dark lines
crossing the "lands" in every direction. These narrow lines are the
markings which have since been so celebrated as the "canals of Mars," and
the discussion as to the real nature of these canals has focussed
attention upon Mars in a way that, perhaps, nothing else could have done.
Before 1877 the study of planetary markings was left almost entirely to
the desultory labours of amateurs, skilled though many of them were; since
1877, the most powerful telescopes of the great public observatories of
the world have been turned upon Mars, and the most skilful and experienced
of professional astronomers have not been ashamed to devote their time to
it.
There is no need to pass in review the whole of the immense mass of
observations that have been accumulated since Schiaparelli brought out the
first of his great Memoirs. That Memoir gave rise to an immediate
controversy, for many astronomers of skill and experience had observed the
planet in 1877 without detecting the network of lines which Schiaparelli
had revealed, and it was natural that they should feel some reluctance in
accepting results so strange and novel. But little by little this
controversy has passed. We now know that the "canals" vary much in their
visibility, and "curiously enough the canals are most conspicuous, not at
the time the planet is nearest to the Earth and its general features are
in consequence best seen, but as the planet goes away the canals come out.
The fact is that the orbital position and the seasonal epoch conspire to a
masking of the phenomena." This was the chief reason why Schiaparelli's
discoveries seemed at first to stand so entirely without corroboration;
the "canals" did not become conspicuous until after most observers had
desisted from following the planet. Another reason was that, in 1877, Mars
was low down in the sky for northern observatories, and good definition is
an essential for their recognition. But the careful examination of
drawings made in earlier oppositions, especially those made by Dawes and
Green, afforded confirmation of not a few of Schiaparelli's "canals"; even
in 1877 a few of the easiest and most conspicuous had been delineated by
other astronomers before any rumour of Schiaparelli's work had come
abroad, and as Mars came under observation again and again at successive
oppositions, the number of those who were able to verify Schiaparelli's
discoveries increased. It has now long been known that the great Italian
astronomer was not the victim of a mere optical illusion; there were
actual markings on the planet Mars where he had represented them; markings
which, when seen under like conditions and with equal instrumental
equipment, did present the appearance of straight, narrow lines. The
"canals of Mars" are not mere figments of the imagination, but have a real
objective basis.
As this controversy has passed away, another and a very different one has
arisen out of an unfortunate mistranslation of the term chosen by
Schiaparelli to indicate these linear streaks. In conformity with the type
of nomenclature adopted by previous areographers who had divided Mars into
"seas," "continents," "islands," "isthmuses," "straits" and the like,
Schiaparelli had called the narrow lines he detected "_canali_", that is
to say "channels," but without intending to convey the idea of artificial
construction. Indeed, he himself was careful to point out that these
designations "were not intended to prejudge the nature of the spot, and
were nothing but an artifice for helping the memory and for shortening
descriptions." And he added, "We speak in the same way of the lunar seas,
although we well know that there are no true seas on the Moon." But
"_canali_" was unhappily rendered in English as "canals," instead of
"channels." "Channel" would have left the nature of the marking an open
question, but, in English, "canal" means an artificial waterway. Here then
the question as to whether or no Mars is inhabited comes definitely before
us. Have we sufficient grounds for believing that the "canals" are
artificial constructions, or may they be merely natural formations?
In 1894, Mr. Percival Lowell founded at Flagstaff, Arizona, U.S.A., a
well-equipped observatory for the special study of Mars, and he has
continued his scrutiny of the planet from that time to the present with
the most unrelaxing perseverance. The chief results that he has obtained
have been the detection of many new "canals"; the discovery of a number of
dark, round dots, termed by him "oases," at the junctions of the "canals";
and the demonstration that the "canals" and certain of the dusky regions
are subject to strictly seasonal change, as really as the polar caps
themselves. In addition, he has formed the conclusion, which he has
supported with much ingenuity and skill, that the regularity of the
"canals" and "oases" quite precludes the possibility of their being
natural formations. Hence there has arisen the second controversy: that on
the nature of the "canals"; for Mr. Lowell considers that their presence
proves the existence of inhabitants on Mars, who, by means of a Titanic
system of irrigation, are fighting a losing battle against the gradual
desiccation of their planet.
In a paper published in the _International Scientific Review_, "Scientia,"
in January, 1910, Mr. Lowell gave a summary of his argument.
"Organic life needs water for its existence. This water we see exists
on Mars, but in very scant amount, so that if life of any sort exists
there, it must be chiefly dependent on the semi-annual unlocking of
the polar snows for its supply, inasmuch as there are no surface
bodies of it over the rest of the planet. Now the last few years,
beginning with Schiaparelli in 1877, and much extended since at
Flagstaff, have shown:
"The surface of the planet to be very curiously meshed by a fine
network of lines and spots.
"Now if one considers first the appearance of this network of lines
and spots, and then its regular behaviour, he will note that its
geometrism precludes its causation on such a scale by any natural
process and, on the other hand, that such is precisely the aspect
which an artificial irrigating system, dependent upon the melting of
the polar snows, would assume. Since water is only to be had at the
time it is there unlocked, and since for any organic life it must be
got, it would be by tapping the disintegrated cap, and only so, that
it could be obtained. If Mars be inhabited, therefore, it is precisely
such a curious system we should expect to see, and only by such
explanation does it seem possible to account for the facts.
"These lines are the so-called canals of Mars. It is not supposed that
what we see is the conduit itself. On the contrary, the behaviour of
these lines indicates that what we are looking at is vegetation. Now,
vegetation can only be induced by a water-supply. What we see
resembles the yearly inundation of the Nile, of which to a spectator
in space the river itself might be too narrow to be seen, and only the
verdured country on its banks be visible. This is what we suppose to
be the case with Mars. However the water be conducted, whether in
covered conduits, which seems probable, or not, science is not able to
state, but the effects of it are so palpable and so exactly in accord
with what such a system of irrigation would show, that we are
compelled to believe that such is indeed its _vera causa_."
Beside the bulky _Memoirs_ in which Prof. Lowell has published the
scientific results obtained at his observatory at Flagstaff, and papers
and articles appearing in various scientific journals, he has brought out
three books of a more popular character: "_Mars_"; "_Mars and its
Canals_"; and "_Mars as the Abode of Life_." In these he shows that to the
assiduity of the astronomer he adds the missionary's zeal and eagerness
for converts as he pleads most skilfully for the acceptance of his chosen
doctrine of the presence of men on Mars. In the last of the three books
mentioned, he deals directly with "Proofs of Life on Mars." The presence
of vegetation may be inferred from seasonal changes of tint, just as an
observer on the Moon might with the naked eye watch effects on the Earth.
But though "vegetable life could thus reveal itself directly, animal life
could not. Not by its body but by its mind would it be known. Across the
gulf of space it could be recognized only by the imprint it had made on
the face of Mars."
"Confronting the observer are lines and spots that but impress him the
more, as his study goes on, with their non-natural look. So uncommonly
regular are they, and on such a scale as to raise suspicions whether
they can be by nature regularly produced" (p. 188).
"... Unnatural regularity, the observations showed, betrays itself in
everything to do with the lines: in their surprising straightness,
their amazing uniformity throughout, their exceeding tenuity, and
their immense length" (p. 189).
"As a planet ages, its surface water grows scarce. Its oceans in time
dry up, its rivers cease to flow, its lakes evaporate (p. 203)....
Now, in the struggle for existence, water must be got.... Its
procuring depends on the intelligence of the organisms that stand in
need of it.... As a planet ages, any organisms upon it will share in
its development. They must evolve with it, indeed, or perish. At first
they change only, as environment offers opportunity, in a lowly,
unconscious way. But, as brain develops, they rise superior to such
occasioning.... The last stage in the expression of life upon a
planet's surface must be that just antecedent to its dying of
thirst.... With an intelligent population this inevitable end would be
long foreseen.... Both polar caps would be pressed into service in
order to utilize the whole available supply and also to accommodate
most easily the inhabitants of each hemisphere" (pp. 204-11).
"That intelligence should thus mutely communicate its existence to us
across the far reaches of space, itself remaining hid, appeals to all
that is highest and most far-reaching in man himself. More
satisfactory than strange this; for in no other way could the
habitation of the planet have been revealed. It simply shows again the
supremacy of mind.... Thus, not only do the observations we have
scanned lead us to the conclusion that Mars at this moment is
inhabited, but they land us at the further one that these denizens are
of an order whose acquaintance was worth the making" (p. 215).
For the moment, let us leave Prof. Lowell's argument as he puts it.
Whether we accept it or not, it remains that it is a marvellous
achievement of the optician's skill and the observer's devotion that from
a planet so small and so distant as Mars any evidence should be
forthcoming at all that could bear upon the question of the existence of
intelligent organisms upon its surface. But it is of the utmost
significance to note that the whole question turns upon the presence of
water--of water in the liquid state, of water in a sufficient quantity;
and the final decision, for Mr. Lowell's contention, or against it, must
turn on that one point. The search for Life on Mars is essentially a
search for Water; a search for water, not only in the present state of
Mars, but in its past as well. For, without water in sufficient quantities
in the past, life on Mars could not have passed through the evolutionary
development necessary to its attaining its highest expression,--that where
the material living organism has become the tabernacle and instrument of
the conscious intelligent spirit.