The New York herald., 1874-07-02
Soientific Sketch of the Celestial
Visitor.
What May and May Not Follow the
ApparitiOn.
Diagram of the Cometary
Position.
GLmPsEs OF COMET HISTORY.

enOn VIII De more clearly witnessed tnls evening
and from night to night for three weeks to come 1t
WIN grow on the curious interest OF the public. In
former days, before science had laid about her with
club and demolished ten thousand OF the empty
ianctes that formed the staple facts Of the world
. comet was dreadful thing to see. 1t was sup
posed to be some wild, errattc creature cut loose
from her moorings In the celestial depths and
eway1ng her tail around ike an
Arctic whale, threatening misery and
death to all within Its reach. Though anybody
who desires can see tonight, from the top OF four
story house. yet better still from the top OF seven
story, comet coming full tilt towards this planet
Of ours nobody seems afraid. The general cry is,
'Let her come % The curiosity to see this most
interesting visitor from the starry heavens Is
working itself up to pitch of intensity. She has
time, exhibiting herself at many remote points OF
the heavens.
CoNETARY CHARACTER.
To Professor Parkhurst the public In former years
were indebted for much concerning the nature and
history Of comets. The present visitor was dis
covered. or, rather, rediscovered. by Professor
Swift, ana Professor Parknurst in his enthusiasm,
believes it will prove the most wonderful and In
structive comet In the history OF the world. or
the real nature OF these everlasting travellers of
the universe no exact conclusion has been reached,
of light on the comet and the character of her
tall which seemed to be the greatest puzzle
Of all.
NATURE OF COMEr's TAI.
Professor Peirce, when Professor of Astronomy
IN Harvard in 1850 calculated the tall OF Donatrs
comet. In communication to the Astronomical
Journal IN that year he said d:-"Each particle or
matter which composes the tail Of comet Is sup
posed to move in hyperboiic orbit and with the
sun In the focus Of the opposite branch, and un-
der the influence OF repulsive force emanating
from the sun and decreasing by the law OF the
square Of the distance. The mutual action Of
OF the comet ITSELF and even the enect OF any
explosive force at the moment OF expulsion
from the planet. The radius OF the comets sphere
OF action Is also neglected In the first apprOxima.
tion, 80 that the particle at the instant OF leaving
the comet moves in the hyperbola, which is tan
genital to the path Of the comet with velocity
IDENTICAL with that OF the comet"
AN ENORMOUS CAUDAL APPENpAGB.
Professor Parkhurst as far back as week ago.
computed the position and probable apparent mag
nitude of the tail he did this in order to learn
whether It would be long enough to extend beyond
yne earth's orbit. he concluded its length to be
1900 900 miles, and assuming an increase of length
result that upon July ao-Sns fortunately, % alter
. rapturous ana patriotic people-the tail Of that
unconsctOnabe comet would positively strike the
In insurance. ParEhurst had some lew doubts
about this and he entered into some further obser
vaSn He sno Ss med IN the
At sweeps across the ecliptic that 1t Will fill
siderable part OF the heavens, or, II it's curvature
Within it. he thinks 1t too early to determine
whether the phenomenal spectacle NAV not be
confined to the hours Of daylight in America. This
A SORE DISAPPOINTMENT.
II we cannot see this celestial peacock Of the one
70 back and coquet with Jupiter; but II she can.
not let an eager public see her lustrous candle
was cut Oh and she was sent to wander In the
"A1lky Way"
THE SIGHT THIS EVENING
This evening at half past nine O'Clock the comet
will be easily seen py the naked eye IN the north
western SKY, with q tan about i've degrees In
By keeping outside the outrageous observation Of
the trees and looking in the OF the Hudson
Rvsr north ana probably IN the M 81 direction Of the
be observed. From the Pointers to the Pole Star
1t will be necessary to keep sharp lookout at an
the Pointers and the Pole Star for the points OF
the base, and near the apex 1t may be possible to
south. In few weeks rom now the head "vSli viii
have reached the horizon IN the northwest at the
end oftvilight, while the tall VIII extend to the
DoNAfI's COMET.
According to Professor Parkhurst Donati's comet
had retrograde motion, and when the earth met
1t and the tail was most brilliant 1t was placed
nearly at sgh angles with tine line Of Vision
greater. eomins Just Within the 'et Orbit ''s
Venus moves In the same direction with
Eeduced TO- the plane OF the Equator). in conse-
Quence OF which the tall, which is now nearly at
% taS ansss wS s pdnns
nearly in the same direction. 1t will be remem-
bered that DONATES comet was curved ike sol
nearly straight, because the curvature will be a.
rectly from us, and therefore imperceptible. An
other striking
DIFFERENCE FROM THE TAILS
Of comets generally Is that It win be so foreshort-
snsd e Is TO to BE- be- re%%srxaoly % wide at the end on
rapidly toward the end Within three or our days
panded In the neighborhood OF the Pole as to nll
large part Of the northern heavens Yet II will
faint as to hook rather like an Immense cloud or a
new MILKY Way than what It really Is. BY this
stme We. shall have solved the question whether
"A"' 80 ''' WHAT is ro BE THE upsuor,
OF the way In which this win end 1t is not safe
yet to speak with defntteness; for although il the
tail were straight we should be almost Certainly
@ ds OF see ays s
until the earth has passed beyond ITS path. The
comet win then disappear to us; but then the in
be Ignorant Of the
CAUSE OF THE LUMINOSITY
OF the evening sky, viii see 1t gradually rise and
pass away, and Will be amazed by the sudden ap-
pearance OF comet OF extraordinary size and un-
usual 6riliancy, which Will burst upon their vision
"a unforeseen as the great comet OF 1851. The
gradual dlminution and fnal disappearance OF the
comet viii be SO nearly the converse OF what we
shall have witnessed here that 1t needs no descrp
t1on. II VIII, Of course leave us portion OF its
atmosphere when 1t departs, but probably
not enough to AFFECT the barometer, or to come
nj Cto uftofu mt
there may be, BY possibility, one permanent effect
OF scientific interest and curiosity. II the earth
should not entirely escape the moon will also
tlon Of the cometary substance. As the amount
OF the atmosphere upon the moons surface is now
30 small, H. indeed, there Is any at ALL that It is
unrecognizablc BY the incest astronomical scru-
hc, lily, perhaps after the passage OF the comet we
atmosphere Of greater or less density, which Will
mateIially modify the phenomena of occultations
sna M leo aoa, eciipses Venus is safely ont OF the way