New-York tribune., 1841-12-14
Y HE TRIBU N E -.
Dr. Lardner's SIKH Lecture.

of which. we shall find circums ances not destitute
If interest. The comet Of Halle is not the only
one whose return has been established, and WHICH
ha. been identified as appertaHng to our system.
On the 18th OF Nov. 1913 (althsugh | am not GER
tain a, TO the day of the month"; a comet was OBJ
served a, Narseilles, in France, and i,s motion
was pursued Cor certain time. Its course was
carefully noted and the calculations sen, TO Paris
and laid before the Institute NJ Arsge, by com
putatons, the nature of which we have already
explained proved that it was identical with the
one which made 1t. appearance in 1903. Proies-
sor Enckc, PrsssieH astronomer, whose name
has been widely known in connection with
this comet as well rs for his general Astronomical
discoveries, followed it in its revolutions, and
showed that it had bees revolving around the Sun
6, long as the Solar System had existed in a GER
tain orbit which he defined, and in period of
| 300 DAYS Thi. has since been called Encke :
Comet 1t is extremely small and insignificant, so
far as It's mass and weight are concerned, but of
extreme interest and importance from other cir
cpustances connected with it. Enckc closely fol-
lowed its path and predicted its return in 1922,
1925. Sc at the intervals already mentioned. His
predictions were ful6lled and the comet has aP-
peared TO this day as regularly as any Of thu plan
cts, and is recognized quite as necessary to the
Solar system as Jupiter or Mars.
In April, 1928, German officer Of Engineers,
named Bella. observed another csnet, whose re-
turn he carefully watched. Like Encke's Comet,
!, was extremely small, very misty in its appear
ance. and of exceeding evity. He perseveringly
hunted It's path, and f-und Ihatit likewise followed
a regularly defined path, and completed its revou-
ton in reasonably short time.
These two comets arc essentially different in
their character from that OF Halle, especially in
the length Of their years which is much less, that
If Bella making its revolution in period OF six
Years and eight months. The comet OF Encke re-
wolves in IN orbit the nature of which may be ex-
planned in this way: it approaches nearer
the Sun than Mercury, and is never at a greater
distance from it than Jupiter so that it revolves
in an oval the part of which comedies with
the path of Mercury, and the most remote with
that of Jupiter, the comet revolving between these
two Both these bodies are exceedingly insignia
cant. 80 far Us their magnitude and weight
cerncd A diagram of that of Bella have already
exhibited to you it is the one through whose very
centre Sir Joha Herschcll small cluster of
telescope stars of the sixteenth msgitude-which
the slightest intervening fog would have rendered
invisible The comet is extremely tossy in its ap-
pearance destitute of all solidity, and is even more
rare than the vacuum created in ar air-PumP by
the exhaustion Of its contents. This fact, which
in itself is of slight moment, acquires u vast I'M
portance from the following circumstance.
1t so happens that the path of tn comet, which
makes its revolution in six years and two-thirds,
does directly ntersect the path OF the Earth. Al
every revolution it directly crosses our orbit 1t IS
therefore within tho bounds of probability, nay.
putting out of the question the consideration OF
Tine, it is within the scope of certainty that both
these bodes-the Earth and the comet-will ar
rive at the same point at the same moment, and
the result will be that the Earth will pass directly
through the body of the comct-if body it has
VIVA, the probabilities of this event are, Ii quite
another question. The prospect of its occurrence
excited considerable apprehension in Europe IN
1882 So great and general was the alarm in tho
kingdom of France, that Ike French government
EMPLOYED NJ. Arage to write q familiar treatise
upon the nature of comets, IN order 10 disabuse
the great body of the people from their extreme
and paralyzing fear, and 10 show that in the case
of Bela's Comet there was ne aaagct~ OF imme-
date collision The fact was, that by calculating
the motion of Beas Comet, i, proved that
in 1899 it crossed the Earth's orbit on the 30;R of
October, and the Earth passed the point OF inter-
section about z month later. So that if the Earth
had been thirty days sooner this point, coils
ION with the comet would have been inerltable.-
But thi. motion, though small in time, Is vast IN
space, as you will see by considering these facts
In ts orbitual motion the Earth advances AT the
rate Of 2,e00, 900 of miles day; IN thirty days,
therefore, /, passes over 60,00000O OF miles. So
that at the moment when the comet crossed It's
path, the Earth distant from the point OF IN
ieI.ec,ion 60, 100000 of miles.
Now the probability that the Earth and this
comet will arrive at the same moment at the same
spot, may be estimated by considering this: the
comet passes the spot once in six years and eight
months, and the Earth once each year. In order
10 cause collision both must arrive al the same
tme-not AZ the same time in general terms, IN
the same day OF week for as we have seen, II the
Earth should pass the point in the morning. and
the comet IN the evening of the same day, the mo-
,cu OF the Earth in its orbit would in the mean
time have interposed between them distance OF
a million OF miles. But if they cross within such
time tina, the Earth falls into the attraction OF
the comet, the mixture OF conetic matter with our
atmosphere will be inevitable. What would result
in this case we do not know bu, VIC may nudge
somewhat from what we know Of the nature Of the
matter of which this comet is composed. A. has
been already mentioned, through mass of it So
900 miles in diameter, Sir John Hcrschell. in 1882
saw stars which can only be discovered b, the
nest powerful telescopes; so that we know tina, i,
mus, be composed of matter compared with which
All IS infinitely deRse
Blu, connected with these two physical bodies.
there ha, recently been discovered Il Circumstance