Evening star. [volume] (Washington, D.C.) 1854-1972, 1874-07-02
THE APPROACHING COMET.
Startling Developments.

Startling Developments.
THE HEAD OF THE COMET TO BIZ AS NEAR AS
| VENUS IS TO THE RARTH-sTRoNG PRoBA-
| BlLlTT THAT THE TAIL OF THE COMET WILL
ENwRAP THE RARTH AND THE MOON.
| Henry NJ. Psrkhurst writes TO the New York
| Tribune as follows: Permit me again to con-
| graduate Prof. Swift upon the rediscovery of
| what now promises to be the most wonderful
and instructive comet in the history of the
| world. Having ascertained that the nucleus of
| the comet was moving in satisfactory accord
| ance with the orbit which had computed, /
| proceeded on the 26th inst. TO compute the posi-
ton and probable apparent magnitude of the
tail, 10 order to learn whether il would be long
enough TO extend beyond the esrth's orbit, so as
| to be visible at all after the head of the comet
| disappears in the west. From my own estimate
| of ITS length on the morning of the 25th, after
the moon had set, l determined its actual
length at that time TO be certainly over 900 900
| miles. then assumed an increase Of length of
| one tenth each day, aud reached the startling
result that UPON July 20 its tail would actually
| strike our eGrth. But knowing that If the tat
should not be long enough to reach our orbit
IL would fade away in the twilight without
making any unusual display, would not ven
| ture TO publish my result without further
examination.
With later observations Of greater accuracy,
have repeated and extended my computations
and am confirmed in the opinion that we shall
| be either so near the tail of the comet, as it
sweeps across the ecliptic, that il will fill large
portion OF the heavens, or il its curvatureI not
too great, shall be completely enveloped within
| Ii; and the phenomenon may be visible in the
northern hemisphere, although il is too early
yet to determine whether It may not be during
the hours of daylight IN this country. At the
rick OF having erred in my judgment, that the
brightness and condensation of the nucleus and
attendant coma indicate the formation OF a tail
equal to that OF Denati's comet, which watched
with so much care, will venture some predic
lions, trusting that they may re received with
more confidence than my early predictions OF
the future OF Donati's comet, and til at they NAV
be as fully confirmed.
On Tuesday evening, June 80 a, and on the
following evening. the moon will rise before the
twilight fairly end; but on THURSDAY, July 81,
at OK O'Clock, the comet will be easily seen BY
the naked eye in the northwestern sky (n1
other description will be needei) with a tai
about deg. in length. On succeeding evenings
the nucleus will move towards the south, while
the tail will Increase IN length, so a. TO bring
It's extremity gradually northward. On the
18Th of July the head of the comet will have
reached the horizon in the northwest at the end
of twilight, so that it will not easily be visible
after that date, but the tail will extend nearly
TO the polestar.
DOnati's comet had a retrograde motion, ami
when the earth met it, and the tail was most
brilliant, it was placed nearly at right angles
with the line of vision On the other baud, th.
comet, whose perihelion distance Is very Little
greater, coming Just within the orbit of Venus.
moves an the same direction with the earth, a1d
nearly with the same velocity (Teduced 10 the
plane OF the equator In corseq gencs or which
the tall which i nov nearly At right angles
with the line of vision, will gradually turn TO
wards Us, still apparently pointing nearly in tee
same direction. Il viii be remembered thai
DonGt's comet was curved like a sOldier's
plume, but COggia's is now and will remain
nearly straight, because the curvature will be
directly from u, and therefore imperceptible
Another striking difference from the tails OF
tSgenerally Is that IL will be so foreShort-
ened as 10 be remarkably wide at the end.
On July 10th, the tail will extend far beyond
the pole and develop new charact eristic, ia
perIng of rapidly toward the end. Within three
or four days after the 10th, the tail will have
| become SO expanded in the neighbOrhOod of the
pole as to fill large part of the northern hesv
ems. Yet it will not be a conspicuous Ob'est,
because 1t will be so faint as to look rather like
al immense cloud, or a new miIky-way, than
what IL really is. By this time We shall have
solved the question whether the tail is hollow
or has radiated structure, or what is its con
sttution.
OF the way in which this will end, it is no,
safe yet 10 speak with deinteness; for although.
il the tail were straight, We should be almost
certainly near the middle OF IL on July 10th, vet
its curvature will probably delay it two or three
days, and even until the earth has passed be-
yond its path. Taking the best value can from
the records OF previous comets, should expect
the earth Oh July I'D to be wholly within the
eastern edge of the comets tail; and will AS
sumo this to be the case. The comet will then
disappear to Us; but then the inhabitants Of the
southern hemisphere, who may be Ignorant o.
the cause Of the luminosity of the evening sky,
VIII see 1t gradually rise and pass away, auO
will be amazed by the sudden spparition of
comet Of extraordinary size and usual bril-
liancy, which will burst upon their vision a.
unforeseen as the great comet of 1861. The
gradual diRiDution and final disappearance OF
the comet will be so nearly the converse o.
what we shall have witnessed here that it needs
no description.
What will be the effect on the earth? | dare
not predict the effect on the minds of men, es-
pecially OF the ignorant; but do not anticipate
any appreciable physical effect further than
possible electrical phenomena like the aurora.
III Will, OF course, leave Us q portion OF its as
mosphere when it departs, but, probably, not
enough to effect the barometer, or to come with
In the cogniZance even of scientists. But there
may, by be possibility, one permanent effect OF
scientific interest and curiosity. IL the eartE
should not entirely escape, the moon will also
probably be involved, and it will also retain
portion Of the oometsry substance. As the
amount of atmosphere upon the moons surface
ls now SO; small, if, indeed, there is any at all
that ii is unrecognizable by the incest astro-
nomical scrutiny, perhaps after the passage OF
the comet we shall find that henceforth the
moon will have an atmosphere, Of greater or
less density, which will materially modify the
phenomenon OF OCCUPATIONS and solar eclipses
will add that Venus is safely out Of the way,
SO that the transit expedition will not be inter
fered with by the great comet of 1874.
In Gould's Astronomical Journal Professor
Pierce has developed means of computing with
great accuracy, from observed phenomens, thu
form of the tail OF the comet intend, as soou
as shall have the necessary materials, TO at
tempt to determine with more exactness the
position and appearance OF the comst's tail
from the middle of July up TO its final disap-
pearancein this hemisphere. have, therefore
retreined from giving IN this article the exact
details of the results shown by my computations
If THE TAIL ENVELOPES
EARTH.
second card from Prof. Parkhurst, I'm the
New York Tribune of yesterday, says. al have
assumed that the repulsive force is the same in
the case OF Coggia's comet, and find that upon
Peirce's theory, with this assumption, a parti-
Gle OF matter leaving the head of the comet on
June 9th, when the tail was already 2.deg. in
length, would on July 10th be nearly 40, 900 900
miles outside the earth's orbit 1t is evident
therefore, that the first requisite of magnif-
cent display, length OF tail, will not be wanting
also lind that particle leaving the head or
II e comet June 2Sth, will also be, on July I'D,
outside Of the orbit of the earth; but that from
Il e curvature Of the tail, that portion OF il will
az pear in or near the constellation Hercules
Since, therefore, the portion of the .tail nearest
to US will be more than two days behindhand in
crossing the ecliptic, it is a. yet somewhat
doubtful whether We shall be involved within
its operations"
The SRPTRNNATE STRUGGLE IN FRANCE
The subcommittee of the committee OF thirty
of the French assembly have drawn up q new
constitutional bill. The measure provides for
the continuance Of the title of president Of the