The farmer and mechanic. [volume] (Raleigh, N.C.) 18??-19??, 1910-05-03

sa.i 70 attract them 10 nor exnIra5
ne Tact that the familiar Gle
60 . carbon, sodium, magnesium
CO.. = nave been discovered in
aSao indicates their kinship to our
aSstem and thus goes far =, e., hSta MI
: me last theory as to their origin.
10 further confirms It bv nainrino
the relation Of the orbits Of
10 TO their origin. According
iiih, The real paths Of
nerhaIo muse be either ellipses or ny
= ooias-elHpses if they are part OF
' ne aolar system, elipses or hvperbo-
q, theS are visitors from infnity.
hee no cometary orbit has been con
slasiNeiy shown TO be ~hynerbolfc. while
liaHy are clearly and uneouiyocsllv
ahp''.a.' ne concludes that the real
orDlts OF comets are elIipses and hence
system. y 0oiai
Inc length, or rather circumference
- .otietary orbits, aud hence the pc
niouicity 4 velocity of comets. vary
wl,nin very wide limits. AS to peri
ne'lon distance Of orbits. the greatest
hho"h is "S5,s0O, 600 miles, in the
Ease OF the comet Of 1923. the least
known $4,000 miles, in the case Of
ne CONT of 1913 IL. As 20 aphelion
Instance, the greatest known IS
7oo'I ~ao.eoe,eo0 miles, in the ease
% the comet Of 1874 CID,
.ho ieaSt Known 1850, 600 miles
III tht case OF Encke's comet. The pc
flods IN which comets travel these i'm
I1ense oistanees-Inore than q ~trillion
miles III some instances~-varv from
" - years. IN the case OF Tncke's
comet, to more than 1000 years, in
the case OF Donatis Comets are be
iieVed to travel very slowly except
when comparatively near the sun,
When they sometimes attain the enor-
4 IlthlS vtG1l ct r1n-o ~- n
miles per second.
Inc FelOcltieS, and consequently the
periods and orbits, OF comets APE oft
en- greatly changed by the influence
OF the planets. The influence Of the
earth LD0n LeAells comet has ALREADY
oeen noted. The four larger planets,
Neptune, Uranus, Saturn, and Jupiter,
have III the same way so changed tn.
orbits Of more than forty comets as
to make them periodic visitors to the
solar system. They have, moreover
made the paths Of many p~araboIic and
sent them courstng out Of our system
never to return. Being attracted ~
the planets, the velocity OF comets
must be Increased or decreased. II
1T is increased. their orbits Will be
heightened into q ~Darabola or hyper
bOla, aaG they viii never return again,
IL it is decreased, their orbits viii b
made more distinctly elliptic, anc
their periods shortened.
The question here arises as to tn,
probability and danger of an ncoun
ter between the earth and a comet
That the danger would be t~reTnendoui
cannot be denied. EO even though
comets are extremely ~a1tenuated. tn
vast 0 Of carbon they would dis
charge into our atmosphere upon al
encounter would render life impOSSi
bic. However. the probability Of al
earthly with one of these
wanderers is Very remote-oniy one
chance in $4,000, 000 cometary visits
according to the most thorough astro-
nomical calculations. 1t Is almost in
conceivable that a comet. rushing
from the intiDity of space at the We
locity of thousands OF miles per min
ute should exactly block the path OF
the earth. whose orbita1 velocity is :
thousand miles per minute.
JOHN NJ. SHIELDS,
Chapel Hill.