Press and daily Dakotaian. (Yankton, Dakota Territory [S.D.]) 1880-1889, 1881-07-02

planets from west to east and the inclina-
tion OF their orbits to the place Of the
ecliptic is not greater than those OF the
minor planets. On account of these
points of resemblance they have been
classed together as the inner group" Of
comets.
Encke's comet, after few returns, ex-
hibited regular shortening Of its peri
cd, 8nd the same was found true of Faye's
comet.
Encke also observed in 1923 that the
light of his comet was becoming fainter.
Prof. D'Arrest has recently called atten-
tion to Encke's remark: "SOOn nothing
will be left of the comet" It is a fact
that from that time to the present it's
brightness has steadily decreased.
The history of Biela's comet, another
of the same group, has been even more
remarkable. In l848 it divided itself
into two parts, almost under the eye of
the observers. and each ipursued it's
course separately. Upon the
comets return in 1862 the
distance of its two parts had
become ten times greater than in 1886;
they were now as completely indepen-
dent of each other, as if they had never
been united. At its return in 1859 the
comet was in SO unfavorable position
as to render its observation extremely
difficult. The computations for the year
1866 gave assurance of most favorable
position, but the comet was not to be
found. There can be no doubt, therefore,
that Biela's comet has totally dissap-
peared.
We thus see that two of the comets of
the inner group are subject to certain
contingencies which threaten their very
existence, and we have reason to believe
that the others will share the same fate.
1t is true that the lattea have not yet be-
trayed any very great changes, but q
fact has recently come to light which is
strongly against the permanent existence
of these celestial bodies.
Most of these comets pass through
orbits which render conjunction of two
comets at one and the same point of the
heavenly space probable and even col
lision Of comet with planet at some
time or other absolutely certain. The
orbit of Encke's comet crosses the orbit
of Biela's comet. This is of little con-
nequence so long as the two comets do
not meet at that point; but they are
certain at some time or other to do this,
and then their union or their division
and destruction is probably inevitable
Apart from this, however, there are
other circumstances menacing the exist.
ence Of each of these two comets. Encke's
comet approaches the orbit of the planet
Mercury, and Biela's thot of the earth
SO closely that conjunction with these
planets must take place at calculable
future period. Indeed there would have
been a fair prospect for conjunction o.
Biela's comet with the earth towards
the latter part of December, 1888 had il
escaped its mysterious destruction.
| The comets of Brorson and Faye pas
through the orbit of Jupiter, and con
junction with this planet, or even clos,
approach to it. will certainly affect thei
existence or their course. De Vico'
comet has similar relation to the plane
Mars.
If we add to this the fact that astron
orners have by very recent computation
demonstrated the possibility of con
} junction OF three or even five comets a
} once, it is easy to comprehend that thei
existence is exceedingly unstable.