The Democratic advocate. [volume] (Westminster, Md.) 1865-1972, 1872-08-03
The Nature of Comets.

oVHiSAS, hhASs ~ His PuIPusc " cAplitH
The remarkable phenomena they present
by an application of the established
principles Of physical science alone.
He starts from the fact that water,
mercury, aud many other substances,
cyen solids, undergo evaporation to a
certain extent and he infers from the
orders Of the metals that they also,
even at very low temperatures, are con
stantly giving of vapor, though 10 an
iuappreciably small amount; from which
he concludes that mass of matter in
space viii ultimately surround itself
with IFS own exhalations, the tension OF
which will depend upon the grayitative
energy Of the mass and the existing
temperature. If the attractive force of
the body be insufficient to give the
surrounding yapor its maximum tension
Tor the temperature, the evolution of
yapor will go 90 until the entire mass
is converted into it. A further analyti.
cal inquiry leads to the result that a
finite mass Of gas 10 unlimited space is
in condition Of unstable equilibrium,
and must become dissipated by continual
expansion and u consequent decrease Of
density; and a necessary consequence Of
this result is that the space contained
ia tie stellar uniyeres must be filed
with matter 10 the from Of gas.
BY assuming for the purposes of
calculation, that stellar space is every
where filed with atmospheric air, and
taking the temperature as that of melt
ing ice, he finds that gas III space, at
it's lower limit Of density, is SO attenua-
ted that mass of air, which on the
earth's surface would occupJ volume
Of one cubic decimeter, would, when
reduced to this density, fill 4 sphere of
inconceivable dimensions; ray Of light
would not traverse its radius in a less
number Of years than is expressed BY
the mineral one followed by ninety
eight ciphers. Such medium could
have no appreciate effect either upon
rays of light or the motion Of bodies.
Solid bodies in space must, by virtue
Of their attractive force, condense the
gas so as to form an atmosphere on
their surfaces, and the density Of the
envelopes eau be calculated when their
size and mass are known The value
found for the moon is vanishing
quantity, and perfectly in accordance
with the fact that no lunar atmosphere
has ever been detected. For the larger
planets, however, the value is very
great, aud the high density Of their
atmospheres must occasion perecptable
effects upon the light reflected by them.
The temperature Of fluid mass,
existing far from the sun or any body
capable Of radiating heat to il, would
be that Of the surrounding space, and
if its attraction were not too great, slow
evaporation would convert it into
sphere of vapor. Should it, on the
contrary approach the SUI, the heat
would cause the whole to be yaporized
in much shorter time than in the
former case, and the smaller the mass
the shorter the time would DO. The
smaller comets, which often appear like
spherical masses Of yapor, are ex implies
OF bodies Of such q nature.
The self luminosity of comets he
sets down to electrical excitement; aud
if it be granted that electricity may be
developed by the action Of solay heat,
in the process Of evaporation or the
mechanical aud molecular disturbances
arising from il, we have cause suih-
cient TO account, not only for their
self luminosity, but also for the forma-
ton Of their trains.
He then proceeds to discuss tho
cumulative difference IN the effect Of
grayitative and electrical forces upon
masses at distance, aud shows that,
when a body is under both Influences
simultaneously an increase Of the mass
results IN preponderance Of grayita-
ton, and sufficient decrease Of the
snme, in preponderance of the electri-
cal action. Hence the nuclei Of comets,
as masses, are subject to grayitation,
while the yapors developed from them,
which consist Of very small particles,
yield TO the action OF the free eIectrici-
~ Of the sun. Careful investigation
shows that, surprising the free electrici-
~ of the SUI to be no greater than has
been repeatedly observed on the Earth's
surface, it would speedily communicate
to a sphere, / | milimeters 10 diameter
aud 100 Of a milligram in weight, a
velocity of over 40S geographical miles
per second, or such that it would pass
over space of over 70,000,000 miles
in two days. The comet of 1850 devel-
oped ia two days train Of $4,000, 900
miles, which is magnitude Of the
order calculated II is therefore sufii
cient 10 attribute to the sun an electrical
energy no greater than that supposed to
account satisfactorily for the appearances
presented by cometic trains; aud ii is
quite unnecessary to assume the exis-
tence of some other repulsiye force.
When cometsappcar with trains directed
towards the sun, instead Of away from
it, such direction is easily explained by
the supposition Of opposite, 10 place Of
like, electrical characters, resulting ia
attraction Instead Of rcpulsion.
Professor zollner and others think
there is no improbability Of the exist
ence in space Of fluid masses such al
described consisting Of water or Of
liquid hydrocarbons, aud the spectra OF
, or,,,o &C tka .,ok,,fa :, :. 4 80, Ill.