The Providence news. (Providence [R.I.]) 1891-1906, 1896-07-11
Great Map of the Heavens
Nearly Completed.
Work on it Has Been in Pro-
greSs Nearly Nine Years.
This Country, However, Has Had No
Share in the Enterprise.

A gentleman who Is very much inter
estea in all matters relating to astron-
omy, calls the Gossiper's attention to
what he says will be, when completed'
one OF the most remarkable and valuable
maps In the world. This map is one OF
the heavens, and work upon II has been
going on for fully nine years. The en-
terprise Is OF an international character.
although, unfortunately, the United
States has no part in it. In preparing for
. the work the heavens were mapped out in
sections. one section being assigned TO
each OF the eighteen observatories in
various parts OF the world. Each OF these
was requested to funish map OF its par
ticular section in 1900 parts. TO do this
300 photographs had To be taken at each
observatory, making grand total OF
54, 900 photographs. Professor Pickering
of Harvard wished to undertake share
of the work. out il was finally decided
that the great amount OF lime required
for the allotted section would interfere
with the general work at the Cambridge
observatories.
The observatories that have engaged in
the work and carried it to successful
conclusion are those of Greenwich, Rome,
Catane, Helsingford, Potsdam, Oxford,
Paris, Bordeaux, Toulouse, Algeria, san
Fernando, Tacubaya, Santiago (Chili).
La Plata, Rio dc Janeiro, Cape OF Good
Hope, Sidney and Melbourne.
What the map will be, when completed,
Is indicated by the statement that 1t will
have. On area of nearly two acres. For
eacn hemisphere there will be IL 900 little
maps, or 22, 900 for the whole sidereal
universe. Upon it will be shown about
so. 600, 600 stars. OF these 2, 900. 900 will
be catalogued and numbered, so that any
star up to the eleventh magnitude can he
located as easily as an island in the map
OF the world. The stars actually shown
upon the map will be all those up to the
fourteenth magnitude. A great number
OF the stars shown upon the map cannot
be seen by the human eye. even with the
aid OF the most powerful telescope. The
phograpbic plate, however, can detect
many millions of stars which no man has
ever seen.
Special apparatus was purchased by
each observa ory for the work. ALI the
instruments must be similar in size and
construction, or the photographs would
not bc alike. The internati onal congress
which was held at the Paris Observatory
eight years ago decided that q telescope
must be constructed for each observatory
engaged in the work. These telescopes
are all of III feet, 3 inches focal length,
with an object glass 13 inches Ia diameter.
To take a stellar photograph Is not
very difficult task. The sitters do not
have TO look pleasant, and the automatic
movement OF the telescope keeps the OBJ
jective always opposite the stars TO be
Dhoto0raphed The delicate part of the
task consists.in the accurate measuring
and placing of the stars shown upon the
pEotographic.plate. Each negative VIII
be transferred In duplicate on copper,
and the two plates will be kept In differ
ent observatories. This is to obviate any
chance OF accident to the plates, for IL
both.were lost, the damage would be- al
most irreparable. Some idea of the mag
nitude of the task now nearly completed
may he gained from the fact that to re-
produce the map from the plates will cost
over s., 000, 900. When TO this are added
the cost of the instruments, the time of
the calculstors and measurers, and the
numberless etceteras which pertain to a
work OF so gigantic nature, the ulti-
mate cost will be tremendous. But the
map, when completed, will be of incstIm-
able value 10 astronomers. The idea is 10
show just what aspect the heavens pre-
sented rt the period represented. Any
changes su bsequent to this period will be
at once detected and valuable Information
gained.