Evening star. [volume] (Washington, D.C.) 1854-1972, 1889-03-30


NAVAL OBSERVATORY Is EXPECTED TO TAKE
PART-THE MANNER IN WHICH IT Is PROPOSED
TO ACCOMPLISH TT-REcENT ADVANCES MADE.
All the nations of the earth that have observ-
| atories and big telescopes are about to Join to-
gether in the work of taking a photograph.
The sky is the object to be photographed-the
sky with all its myriads of stars. As no pho
tographer can get point of view from which
he can focus the whole sky at once, the heavens
will be divided up into sections, and farmed
out to different nations. Capt Phythian, the
| superintendent, and the astronomers at the
naval observatory are anxious to take part in
this international enterprise, but by reason of
the failure of Congress to provide the $4,000
asked by the Navy department for the work,
they have been obliged to delay their prepare
tons until Congress meets again. The money
is required for the purchase of a Photographic
telescope and pointer, the construction of
suitable building and domes the mounting of
the instruments, and to pay for material for
Photographic work. In case Congress makes
the appropriation early in the coming winter,
as is expected. it is thought at the observatory
that the required instruments may be COM
pleted by the time the new observatory build
ings to be erected on the site north of George
town are ready to receive them.
HOW THE WORK WILL BE DONE.
The general plan of the proposed work was
decided at congress of astronomers held in
Paris in April 1887. Lieut. Winterhalter, of
the navy now attached to the naval observatory,
represented the United States in that congress.
The character of the instruments to be used
was determined and many other matters, to
enable an observer in any part of the world to
engage in the undertaking with a correct under
| standing of what the others were doing so he
could make his work correspond with theirs.
tharo will 1ah a11 i'll
the exposition this summer and then the final
details will be settled. The heavens will be di-
vided into zones. beginning with the north pole.
Each zone or section will be five or ten degrees
| in width, and it will be assigned to some OBJ
servatory in convenient latitude.
There is a chain of observatories in this
stellar confederation that will cover every
inch Of the sky, both in the northern
! and southern hemisphere. The French gov
eminent will establish an observatory for the
purpose on Reunion island, off the coast of
Madagascar, and the British government will
have station in New Zealand. Germany,
England. Brazil, Chilli, Spain. Mexico and the
Argentine Republic have each one instrument
III process OF construction. Australia has two
under way, while France has one already COM
pleted at Paris and three others in the hands of
a constructor. 1t is expected. ALSO that instru-
ments, of the kind required, will be built for
other observatories i'll England, Denmark, Aus
tria, and Russia.
lhh lNoIhUMENF USED.
The character of the work makes it neces-
sary that the instruments used in the various
observatories shall be alike. Care must be
taken also to have Photographic plates of the
same degree of sensitiveness. The plates taken
must all be on the same scale. SO when the
whole is completed the work of one observa-
tory can be compared with or combined with
that OF another. The instrument decided upon
is really a double teescope-the Photographic
telescope being combined with pointer or
visual telescope. The pointer" is used as its
name indicates. in bringing the Photographic
apparatus to bear upon the section of the
heavens to be taken. The telescope, which it
is proposed to build for the Naval Observatory.
is a refractor, the Photographic lens being 1874
inches i'll diameter and the visual lens II inches
in diameter. 1t will be swung upon an equa-
torlal axis and have the usual appliances for
operating it. AS star cannot be induced to
remain stationary and sit for its photograph.
the instrument has a clock-work attachment,
which swings 1t slowly in a circle. so as to al
ways keep star or other heavenly body in the
field. The two telescopes are to be constructed
o. the same focal length. so that the images in
both will be on the same focal plain.
Lieut.. Winterhalter told STAR reporter that
the work of photographing would be COM
pleted in two years after it was begun. The
Naval Observatory is situated in latitude
south of the chief observatories in Europe. and
to its share naturally falls a zone or field of
work that could not conveniently be covered
without Its cooperation.
THE PROGRESS OF STELLAR PHOTOGRAPHY.
Stellar photography, although brought to
perfection by the Henry Brothers. of Paris, is
really of American origin. DR.. Henry Draper,
Lieut. Winterhalter said to a STAR reporter
took in 1s40 the first photograph that was ever
secured of heavenly body. The object photo
graphed was the moon. Some years before
when the daguerreOtype process was invented
an effort was made with it in France to secure
photographs of celestial bodies, but the at
tempt was unsuccessful. DIR. Diapers expert
ments gave an indication of the possibilities of
stellar photography. His work was supple
mented by that of Prof. Bond at Cambridge
Mass. At that time the best plates that could
be obtained were not sensitive enough to pro-
duce good results in photographing stars To
get an impression from even the brightest
stars required long exposure, and the work
was carried on under great difficulties due to
the imperfect operation OF Photographic plates
The work was taken up again by Lewis NJ
RGtherfurd, of New York, who cleared the way
| Tor the modern achievements in stellar photo
| graphy. He began by making his own tele-
| scopes, and in his experiments conducted from
| 1860 TO 1870, he used cOllodion plates which
were much better adapted to this purpose than
the materials at the command of his predeces-
| sors. He succeeded III photographing
| stars down to the eighth magnitude.
| stars not visible to the nnaided
| eye. He got pictures of the Pieiades, which
were compared with results of observations by
other methods and ascertained measurements
and found to be mechanically correct. The
| failure Of Mr.. Rutherfurd's health prevented
his pushing his experiments to still greater sue
| cess. He recorded his conclusion that it was
| only question of time when the stars would
| be required to chart themselves on photo
graphic plates. All that was needed, lie
thought, was development of the chemical
processes of photography to produce more
sensitive plates and to insure success. He de-
| signed telescope for such work, a refractor
corrected for the Photographic rays and the
telescope he designed is substantially what has
been since adopted by and approved by the
astronomers Of the world.
| ACHIEVEMENTS OF THE HENRY BROTHERS
| The Henry brothefs, famous astronomers of
Paris took up the experiments where Ruther-
| furd left off, and going Oh in the same line
! achieved marvellous results. At first they con-
structed small telescope and the results were
| so promising that they were encouraged to try
! larger one. With this instrument they were
able to photograph the satellite OF Neptune, a
body so insignificant that no telescope in Paris
| had ever before been able to make it visible
1t is about all that the big glass at the naval
| observatory can do. The achievements of this
instrument in the hands of the Henry brothers
| at once attracted the attention of scientific men
| all over the world. One result was that the
| astronomers of Paris proposed the cnupress