Year: 1860

Encke's comet, which revolves abou; the
sun in 81 years, has been observed 10 complete
its revolution in constantly shortening pc
rod, showing that il is being drawn inward
| towards the sun. This fact has led to the
| general conclusion by astronomers that the
planets are moving in resisting medium, far
moro attenuated than our atmosphere, but still
sufficient to affect their motions. If this is SO,
it follows by strict necessity that our earth and
its sister orbs are all winding spirally towards
the sun, and that they must eventually strike
against it and become incorporated With its
mass. The time required for this purpose be-
longs to those inconeeiyable periods with which
geology and astronomy have to deal. The
resisting medium is so exceedingly attenuated
that it exerts but a.slight influence on the
comets, which are themselves masses Of the
very thinnest vapor, and its Influence would OF
course be very much less on the dense matter
of the planets.


Astronomical observations, with all their
wonderful delicacy, have yet failed TO detect
the slightest progressive shortening IN the pc
RODS of revolution of any of the planets Il
is curious, however, to note the mnltiplea OBJ
staeles which prevent the perception of this
fact, if i: does exist. All tbs measures Of
these revolutions are shortening with the rev.
olutions themselves. Ii we begin. for instance,
with the earth, the problem is to ascertain
whether the time occupied by the earth in its
journey around the sue is gradually becoming
shorter. The FIRST plan that suggests itself is
to compare this with the rotation of the earth
upon its axis, to see whether the year occupies
the same number of days and hours and
seconds that it did ia former times. But il
the earth is gradually cooling, it is contracting
in size, and its rotations on its axis are becom-
ing more rapid in other words, the day is
shortening with the year and if the measure
sbrinks just in proportion to the thing meas
ured, we caunot tell whether the latter is be-
coming shorter or not.


LII We take the time Of the revolutions of
the moon around the earth as a standard, the
same resisting medium would draw the moon
towards the earth, and shorten the mouth al so
with the year. If we resort even to the less
satisfactory measure of the sun rotation on
his axis, his bulk is also diminishing by the
ra4iafion OF BIS hoos, ard tbe pas7ed OF his
rotation Is consequently becoming shorter. In
brief, from the two causes of radiation and the
resisting medium, all the times and distances
which could be used to measure the earth's
distance from the sun for the period of its
ANNUAL revolution) are shortening togetber.-
30 that the difference, in the extent of these
several contradictions are the only meaEs left
for detecting by observation the approach of
the earth to the sun, if such approach is really
taking place. These differences would doubt
less reveal themselves in tae course of genera
tions TO refined astronomical observations.


II the earth and the sun are gradually be-
coming cold, this winding of Inc earth towards
the sun would tend to keep US Its warmth, aud
it may be wise provision for prolouging, by
some millions of years, the continuance of
animal life upon our globe. But this period
must come to close, for if there is a resisting
medium, pervading the space between us and
the sun, the final destiny of the earth is to
curve gradually forward till, with velocity
hundreds of times greater than that of cam
non ball, il dashes itself With au awfully sub
lime crash into the mass of the sun.-Scien-
tifc .fmeracdn.