New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1881-07-01
THE COMET OF 1881.

MS SUCCESSFUL PHOTOGRAPHY-wHAT THE SPEC
TRUM SHOWS.
The cloudess sky of Tuesday night gave Pro-
fessor Draper the wishedfor opportunity of securing
a good photograph of the comet. After exposure
of three hours the plate removed only because
the effect of the starlight showing itself upon
the surface. The tail of the comet is distinctly
visible in this picture to the length of 80 and many
stars visible directly through it. The wanderer
is now seen in the constellation Camelus
in region rich in stars, some of which can be
seen through the tail with an opera-glass, or
with the naked eye Professor Diapers
telescope is adjusted to follow the comets
movement in declinaton, which during the
pOsure of three hours carried it through arc of
several minutes. The consequence that the
photograph presented an unexpected and startling
appearance. Where the stars should have appeared
there certain long streaks, and Professor
Draper fanced that the instrument out of order
until he reflected that the stars. which could not
follow the motion of the comet or the telescope,
must necessarily appear lines and not points.
The most important part of the nights observa-
| tions had to do with the spectrum The nucleus
gave nothing but continuous spectrum. Professor
Draper expected that if the light of the nucleus
comes through the coma, some lines of absorption
would be visible in other words that the contin-
uous spectrum of the nucleus would be crossed by
bands from the coma but either the position was
not favorable. or the lines too faint to be
1
trum of the tall, to see if its light was
original or reflected. If reflected from the
sun it should have shown the features of the
| solar spectrum, but none Of the well-knOwn lines
were visible. 1t seems, therefore, that the tail
| shines by its own light. This would not be
| markable were it not that the tail gives a contin-
uous spectrum, showing that 1T cannot be made of
| gas. 1t seems to be made, the Professor says, of
particles globues like atmosphere of rain, but
self-luminous. The coma differs from both nucleus
and tail in giving spectrum with bands, indicating
| gaseous state. The temperature of the comet
not approach that of the fixed stars. which show
| narrow lines in their analyses, instead of broad
bands. such appear in the spectrum of the comet
| Judging from the analysis, the heat of the comet
should be not far from that of whte-hot metal.
Taking ali the facts into consideration, Professor
Draper thinks the nature of n comet may be in some
measure explained though the explanation is only
a hypothesis The nucleus, upon his theory is COM
posed of mineral substances, partly perhaps, of oil
vine, which is an ingredient of meteorites. and of
some volatile element which yields to the inilu-
ence of heat. AS the comet approaches
the sun, the volatile part is turned
into gas by the heat and flames out to form
the coma. The fact that the is always
suppostion. But after bursting forth on the side
side toward the sun the vapor seems to be repeed,
and to stream away from the sun thus forming the
tail. Now. what the Of this repulsion is can
not be absolutely asserted but in all proba-
| Dllty eectrlclty mas SOuetnlnB 10 10 WIFI
it. There is repulsive force in matter
itself but in matter under the influence of electric
ity there is often repusive force which shows it
possible Professor Draper thinks, to say how cleo
tricty influences the behavior of the and tail
but that it acts in some way is pretty certain.
Nothing else explain the observed phenomena
When the substance that is vOatilized by the sun
is driven away from it by polarity or some other
force, becoming attenuated it quickly cools, and
gathers itself into glObules mist condenses
into rain. The further out these bodies are
driven the they lose their heat
and light, until they longer visible. In thus
way the tail, 1t appears, gradually fades
(, away III the sky. 1t is impossible, however
that the solid liquid bodies forming the tail may
stretch far out beyond the distance through which
: the eye can trace them: until in the end they
| escape from the control of the nucleus and nav
gate the sky mcteorites; This hypothesis is the
more probable, in Professor Draper's opinion
: because at every return upon It's orbit
. its substance and of its brightness. Comets
y of short period are well known to be of fan
n lustre, fact which may be owing to the constant
drain caused by their frequent volatilization under
" the heat of the sum- And when it is taken into ac
:. count that comets and meteoric stones ap
IL parently Of similar constitution, and that they Otter
n follow in the track of comets, it becomes almOs
e certain, Professor Draper believes that comet
1t gradually dissolve into meteorc belts.
The shape of the coma has changed very mucl
"a since Professor Drapers first observations, having
20 partially resumed its birt-like form. but witt
the wings curved forward instead of back and wit
Il in front of them. The activity in the hca
Of the comet is still very great