The sun. [volume] (New York [N.Y.]) 1833-1916, 1906-12-02
MARS As A PLACE TO TNHABIr.

intelligent beings upon Mars?
/ II IL natural to us to believe that this one
little globe is not the sole theatre OF reason
in the vast multitude Of the heavenly bodies;
and what IL is natural for us to believe about
any practical matter, concerning which
error might imperil the continuance OF our
race, can hardly fail to be, at least vaguely,
true. Mind seems to us TO be utterly unlike
anything else; and II il really be 70 its
appearance anywhere would seem to argue
a tendency in it to spring up everywhere,
though that there are some prerequisite
conditions to be satisfied is evident from
the fact that 1t is not everywhere actually
found. It may possibly be that among
the countless orbs in space there is some
other than this earth where there live white
men just like ourselves and speaking the
English language. But it does not seem
likely. because the conditions requisite for
the formation OF our language have Q 10
very special. Now, it may be that
we think OF as intelligence is almost
equally special; no that just as the Greeks
regarded those who did not speak Greek
the so-oalled barbarians-as hardly ra-
tional. we make a great mistake In think
ing hat what we call intelligence" Is the
highest form of being. So it may be; but
there are philosophical reasons for thinking
that It is not SO. and hat reason really Is
something peculiar, unlike anything else,
and therefore. since it is found somewhere,
would be found everywhere where suitable
conditions OF a very broad kind were full
Allied; and the chances are as billions TO one
that such conditions are in fact fulfilled on
many celestial masses.
But as to the planet Mars, the most
infinitely observable body outside the orbit
Of the moon and at the same time Of all
known to u the one on which conditions
are most like those on the earth, Ia it not
possible that we may reach more definite
conclusions1 Ii 80. we must reason by
analogy; and therefore the very first step
upon which every competent reasoner must
and will insist as precedent to all others
will be to examine the respects In which
the analogy between Mars and the earth
fails. BY far the most important OF these
respects is the smaller size OF Mars. Its
dimensions are oaly O-5s those Of the earth.
Naturally. therefore. the material Is less
compressed, the mean density being only
II per cent. Of that Of the earth. The con-
sequence is that gravity on the surface of
| Mars Is only II per cent. Of 0.53, or three
eighths Of gravity on the surface Of the
earth. The pint of water that on the earth
weighs a pound would on & spring balance
weigh but six ounces on Mars. In all
terrestrial things the momentum of a body
at any given velocity is strictly proportional
to its weight. We have NO familiar expe-
rience with any different state of things.
Yet any moving body, say a food Of water,
-. Az. -,-F,AA "A Mas haa tho NV
momentum as it would have upon the
earth. while it presses down on the ground
with only three-eighths Of its terrestrial
weight, and is therefore retarded by fio-
| ton by as much less. Hence anything
which is projected with any force along the
surface Of the planet Mars must move much
further. other things being equal. and along
a much straighter path. and this will in
particular be true of any streams Of water.
Another consequence OF the same facts
is that the mass of Mars is only Il per cent.
| of the cube OF O.53. or about one-tenth Of
the earth's mass; SO that the force Of gravity
at any distance from the centre OF Mars
will be only one-tenth OF the gravity toward
the centre Of the earth at the same distance.
Or, since gravitation varies inversely as the
square of the distance. in order that a body
should be attracted to Mars as much as an
equal body is attracted to the earth the dis
lance OF the former from the centre of Mars
must not exceed 7/vIO Of the distance
| OF the latter from the centre Of the earth.
| Consequently were the temperature the same
| the upper limit OF any given gaseous
! constituent OF the atmosphere would be
| only one-third as high above the centre OF
! Mars az il Is above the centre OF the earth.
| Now. since the very surface Of Mars is much
! higher than one-third the height Of the top
| Of the carth's atmosphere, II Mars has any
oxygen atmosphere at all IL must owe this
TO the fact that the temperature OF the
upper atmosphere is lower than about the
earth. Possibly, for example, the oxygen
| Is there solid. W. may suppose that Mars
| originally had relatively as much atmos-
| phere as the earth had. II 50, it has lost
the bulk Of it through the weakness of it's
attractive force; and II probably now retains
excessively little except what is composed
OF substances partly CONCEALED and so with
out expansive energy. In view OF this slight
atmosphere, very little erosion Of any OF the
kinds that are familiar to us on the earth can
be active on Mars. Erosion Of a different
kind there must, however, be; for the direct
radiation Of the sun on the surface OF Mars
must have a heating effect fully quadruple
It's effect on the solid surface Of the earth;
since, II we remember rightly, the late
lamented Langley showed that nine-tenths
of the suns heat is cut of in the upper
air I'VE may have the precise value wrong
Mars is half as far again from the sun AS
the earth 10. and so receives on a given
area only four-ninths as much heat. This
refers to the top of the atmosphere. That
Of Mars absorbs hardly at all, that of the
earth at least eight out Of every nine parts;
h,nce at the solid surface the suns radia-
ton has four times the power on Mars that
IL has on the earth.
In the spring Of the Marian year (of 6sS
days) lofty ice caps cover it's pole, and prob
ably there are other places where ice has COL
lected on mountain tops. Under the blaze
Of the sun. instead Of glaciers breaking OF
icebergs from their bases as on our own
planet, a~valanIheso Of ice IN come thunder
ing down from the submits. II they did
not find channels ready cut for them by
-..x;.Js If forner stIoh maaaea thav uo,,IJ