Evening star. [volume] (Washington, D.C.) 1854-1972, 1898-02-19
THE ATMOSPHEREs OF PLANETS.
A Theory That There IL No Winter nm
Mars.

Mar1. 80.
From the Literary Digest
A very curious method has very recently
been used by DIR. G. tombstone Stoney. the
English physicist, to find the composition
of the atmosphere of the planets. Some
time ago DIR. Stoney accounted for the alb
se1ce of an atmosphere on the moon by
reminding us that according to the accept
ed theory of gases every gaseous molecule
moves in straight line with great veloc-
ity till 1t is turned aside by an encounter
with another molecule Since the moon is
small body whose attraction is slight,
the gases around 1t would in course of
time dart off into space, particle by par
ticle, only those being left that are close
to the surface, where the attraction is
strong enough to hold them. This would
be true also for any other heavenly body
but the larger the body the greater the dis
lance at which its gravitation would hold
the gas, and the thicker it's atmosphere
would be. As the molecules of lighter
gases move with higher yelocities these
would fly off when heavier gases remained.
This would account for the rarity of free
hydrogen in the earths atmosphere. The
discovery of the gas heiium together with
the certainty that it is not found free in
our atmosphere, has enabled DIR. Stoney
to make his data more exact, since helium
is twice as heavy as hydrogen. Says Ma
ture. In review of DIR. Stoney's paper,
which appears in the Transactions of the
Royal Dublin Society:
1T is commended that helium is contin-
ually being supplied to the earth's at
mosphere from hot springs, that 1t exhibits
no tendency to combine with other ele-
mentS. and since no trace of 1t can be
found In the atmosphere. 1t escapes above
as rapidly as it enters below Water va,
por. on the other hand. remains on the
earth, and consequently limits of speed can
assigned between gas aft
imprisoned or are free to escape"
From calculations based on these facts
the following conclusions are reached re-
garding the atmosphere of the different
planets, using the known intensity of grav-
national attraction on the surface Of each:
Limiting the inquiry to a temperature
of Sc degrees c., DR.. Stoney applies the
theory to all members of the solar system
with the following results: From the moon
all gases having vapor density less than
30 will pass with greater promptness thar
helium does from the earth. On Mercury
water cannot exist, while nitrogen and oxy-
gen would gradually dribble away. The
conditions on Venus resemble those on
earth, but the case of Mars is of excep-
tional interest. Dr. Stoney says that it is
legitimate to infer that this planet
water cannot remain. The atmosphere he
considers to consist mainly of nitrogen, ar
gon and carbon dioxid. He thinks there is
no vegetation, as we understand the term,
on the surface of the planet. and the snow,
frost and fog do not arise from the same
cause as on the earth. Jupiter is able
to imprison all gases known to chemists
but whether the more distant members of
our system can retain hydrogen Is doubt
ably float in their atmospheres, but the
molecules of the lighter gases are describ-
ing orbits about the sun, the velocity they
can acquire enabling them to escape from
liberate them from the gravitational infiu-
ence of the sum-"