Evening star. [volume] (Washington, D.C.) 1854-1972, 1874-07-08

ting my commune alton In the Tribune on Julv
4. have satisfied myself that the delay OF the
comets tail from. curvature will he about four
days, during which time the earth wiil have
moved 30 far that no probable errors OF COMMA
tston or OF estimation would bring ~ within
IL. Having settled that point, I shah Introduce
illustration which otherwise might have
been too suggestive OF danger. A TALL msn,
having an INDIA rubber club two feet long and
three inches in diameter ~ the END, sees q spa
der running very rapidly across a table. lie
raises his club alOft II arms length, snd brinss
~ down with terrific blow. He aims fOt =
point two feet In advance OF the spider. a. %
allow for It's motion, and strikes very nearly the
point which the spider would ffsse res "a 81 she-
the club struck the table; but in crn-so aeuce
OF the club bending little more n an he anti
cipated, the spider escapes by one inch. This
IL an approximate representation on a small
scale OF what viii take place within the neat
three weeks, with two exceptions. In the urst
place, the club, instead OF being o. rubber, Il
OF such sttenuated msteriai that n the saider
were bat he would not know IL. aud srcon Nv an
ordinary spider would be many Thousand times
too large 70 represent the earth. Perhap. I
should add q third, that the SIC OF TIE rIIS =
only knsSn from estimates. since it NAV in
crease an thickness during the blow.
ON July estimated the length o. the tail u
The comet 10 be f, but the end OF " VS. -
faint that many Per sons saw ~ not much more
than half that distance. Ou July 3 4 s--imatad
the length TO be \ and a company OF persons
with me vEries in their estimates from h u IT,
by comparison with stars known 20 me- aul
one, "ty the ali OF little imaciuatipp.r ,s,nli
see it Tor eneth % 10. Taking INV own esti-
mates, the tail had increased in len tn 80 per
cent. within these tive DAYS. although part of
tins tnsy be due 10 unnoticet haze IA TIE atm1s-
pEere On the 81.
indicates that u Will have an equality on .Iuly
II with the star Altar, the brightest Star With
three exceptions Vie BILE in the evening With AZ.
As Donau's comet elualed Arcturns iu bright
ness, am by no means csniident that ne pres-
snt viii be equally bright.
The motion OF the earth is $50 Gao miles par
day; that OF the comet about 400 % 10 miles per
day, and will continue about the same 30 long as
itrtmains visible. The motion OF mat part of
the tail nearest us is nearly 6.e1O,0l0 miles per
day, that Is, 20 miles per second which il 200
times faster than the motion OF an express train.
The thickness Of the tail ] assume ~ about
100000 miles AZ the distance OF 2000 600 miles
from the bead. when it shall have reached that
length. IL tie earth we're 10 pass centrally
through II, the passage would Occupy about a
hours. Passing through the extreme edge as
At nrst thought possible. would not occupy more
than four Ia six hours. Ny computats indi-
cate that the nearest approach % the center of
the tail will be not less than 40O0 alD miles
which would be distance from the "a &c Of the
tail Of BOO 600 miles which 10 ak times tue dis
tance OF the moon. But this will be 81 GENTLY
near 20 cause IL 20 appear enormously large N
II can be seen al all, Of which hope 70 De able
to speak more definitely within a few DAYS. One
thing If certain, IL viii be there whether We can
see IL or not
PROFESSOR swIFr's VIEWS
Professor Swift SAYS in the Herald The
pereheliOn distance OF the comet is about
63,OO0,O miles, or y little within tae orbit OF
Venus. Consequently for the tail 70 reach the
eaTth's orbit IL would extend from the head a
distance Of about 25,o0O,oOO miles. VIII il ex-
tend that distance during u visibility I think
il will, and more; but here the question arises,
will the earth be at the right point ia It's orbit
to become immersed in the cOmetic mStter OF
which its tail Is composed? NV opinion l. We
will escape II entirely and 50 viii the moon.
The tail has beer increasing In length lately
az the rate OF some 100000 miles per day. It's
rate Of increase Is now much greater, aud will
within few days be enormously greater The
comet Is large one snd 80 L. tue nucleus,
which IL very bright, with q disc more plane
tary than stellar. The tail IL wide la proper
ton TO its length, but that ratio OF width @
length = row too rapidly changing.
SHALL WE Tx kNVELoPED IN THE rAIL2
Professor PaTkhuTst has given the subject
much more attention than 4 have. and bis
opinion is entitled 60 great weight. should the
tail increase in width (which L. imprObab!e) as
well as in length, ana should II be not too much
curved, IL Il not impossible but that We may be
envelOped IT, But 1 question il we should be
sensible OF il il We were, the matter OF which ID
lie composed being 80 rare.
THE ELEMENTS or THK COMET
do not agree with any comet that has appeared
during the last 600 years. As its orbit il no
doubt parabOic, n i visiting for the first aud
last time. BY the spectrOscOpe we viii learn
during the next two weeks more about the
physical nature of comets than we have learned
during the last coo years.
Last night WAS the first time since the with
drawal OF the moon, bur unfortunately The sky
was cloudy. From a few sllstched views had
of IL, through the ritts In the clouds, came 30
the conclusion that there was less indication Of
subdivision OF the tail than on the previous
evening. That, however. can DC quickly done
in world OF 50 much activity.
THE COMETS NOTION.
The rate OF motion, even now, Is eunrmOus,
being thirty miles a second, and almost directly
towards us-b1t is direction now viii begin 70
charge.
The distance Of the comet from the earth AZ
this date e. roughly speaking, 90 OJ),c1J miles;
loI gitude or perehe!iOn about - degrees; of
node, about 1,o degrees; inclination OF orbit 20
earth's orbit some - degrees. These clements
are only Approximate, as its apparent motion -
so slow. But small part OF its visible orbit
has been seen.