Year: 1878

Probably the most convenient assump-
tion we can make is that there may be
creatures in q general respect like our.
selves on those moons of Mars, but that,
owing to the extreme rarity of the at
mosphere, their vital energy is so far
reduced that they are not more active
than we are, despite the feeble action of
gravity in the world. The air must be
exceedingly rare, most certainly, even
if the quantity is proportioned to the
volumes of these moons. On this as
sumption the quantity of air is less than
the quantity of terrestrial as one is less
than 400 times 400 times 40O-that is,
it amounts only TO 1-64, 900, 900 part of
terrestrial air.


Being spread oxer a surface which is
but 1-l60. 900 of the earth's, it follows
square mile OF sIirface is Loo 46Dp part % oniy
of the quantity over each square mile
of the earth's surface. This would be
little enough in all conscience; but this
is not all. For the action of gravity
being, according to our assumption, only
1-600 of terrestrial gravity, it follows
that the atmospheric pressure, and
therefore density, is further reduced in
this degree, giving finally q density of
equal only to 1-240, 900 of the density of
our own air.


Now, at a height of seven miles, where
one-forth that at the sea level, men of
ordinary constitutions would perish in
few minutes, if not instantly. In Cox
wells ascent to nearly that height,
Glaisher tainted, and Coxwell only Just
had strength left to draw the valve string
with his teeth, (his hands being already
powerless). Yet at the height of seven
miles the density of the air is 10000
times greater than that which, according
to our very reasonable assumption,
prevails at the surface of the Martian
moons.


We can very well believe, then, that
in whatever way the inhabitants of these
moons may be adapted, corporeally and
constitutionally, for existence in their
small homes, the rarity of the air there
must tend to reduce their vital energy.
So that we ma we'll imagine that,
instead of being able 10 leap to height
OF half q mile or over O distance of two
or three miles, they are not more active
than we are on earth with 600 times
greater weight, but far more effective
respiration. We might, perhaps, go
even further than this, and assume that,
in order to give the inhabitants of these
moons locomotive powers proportioned
in the same way to their own dimensions
as ours are, they must be supposed very
much smaller than we are.


We might imagine them in an atmos-
phere so exceedingly attenuated that
creatures which could have vitality
enough to move freely about must be no
larger than flies or ants, and must have
also some such provision as insects have
for more effective inspiration. In this
way we might find in the Martian moons
a miniature OF our own earth, not only
in the proportions of these worlds them
selves, but also in those of the creatures
living upon them. But it would not be
very interesting to consider mere minia-
lures of our earth, such as the moons of
Mars would thus come to be regarded.
Indeed, in that case, little more could
be said than that all the relations pre-
sented by this earth were or might be
represented in the Martian moons, but
on a greatly reduced scale. PROT Proc
tor, in Beigravi0.