San Antonio daily light. [volume] (San Antonio, Tex.) 1886-1907, 1896-11-20
BEYOND REACH OF TELESCOPE.
Stars Mapped by Astronomers That Have
Never Been seen.


Never Been seen.
In the Cosmopolitan of September
there is an interesting discussion by
Camille Flammarion of the 1.-The New
Eye of Science"-the sensitive plate of
the astronomers Photographic appar-
atus-and of the international under
taking of producing by photography
chart of the whole heavens. The human
eye is an admirable instrument, but its
powers are severely limited. 1t SEES
slowly. 1t requires for vision a COM
paratively strong light, and it retains
no record of what il has seen. The
Photographic apparatus of the astron-
omer, on the other hand. vastly sur
passes the natural eye in these par
ticulars; it sees more quickly. has a
steadier gaze. reaches farther and
makes an unerring record of its visions.
1t requires but the haif-thousandUh part
| of a second for an observation and with
in that brief period accurately maps the
whole field in view. Directed toward
any point of the sky it discerns in the
depths of infinite space worlds the hui
man eye has never seen and never could
see, even with the aid of the best tel
escope. What the sensitive plate does
not detect at the first glance 1T beholds
after time. In five-thousandths of
second it photographs a star of the first
magnitude; in half a second it includes
all smaller stars to the sixth magnitude,
| in Is minutes it has taken in all stars
| to the 14th magnitude. The human eye
is capable of seeing all up to the sixth
magnitude. inclusive, or 1881 stars,
whereas the number that may be
mapped by the exposure of the sensi-
tive plate for IS minutes is over 10000
600.
Recently congress of astronomers
met in Paris to arrange for the con-
certed mapping of the whole heavens,
| agreed upon in 1887. Two thousand
years ago Hipparchus made catalogue
| of 1,022 stars. Present catalogues con-
tain over 100000. But the effort of the
astronomical congress is to make
Photographic chart which will contain
all the 100000 or 100000 stars that
can be found with the light gathered by
y telescope az yards long, having an
| object glass about one foot in diameter.
The work has been divided among 16
observers situated at different points
on the globe. Each observatory is to
make 1900 plates and each plate
| photographs two degrees square. AS
many as 1l,027 plates are required to
cover the entire heavens, and the eel
estial chart they will be used to con-
struct will represent sphere having a
! radius of over 3h yards. Some of the
I plates are to be exposed to the heavens
for five minutes; others for an hour.
The shorter exposure will give ma
terial for a chart to contain $500, 900
stars.
How many will be revealed by the
longer exposure it is impossible to say
till the 1907 sections have been pieced
together and the aggregate made up
after careful inspection. 1t will doubt
less contain many whose existence has
hitherto been unsupported. The long
exposure will produce record of stars
or suns so distant from us as 10 be of
the 18th or 18th magnitude-stars
whose light requires millions of years
to reach US. The vast spaciousness Of
the universe will be evidenced in the mi
mute dots that reveal to praeticed eyes
systems ofworlds not previously known
Large conclusions as to the structure of
the physical universe will perhaps be
suggested by the great chart when COM
pleted. In itself the chart will be a
monument of the patient labors of
science and of the sentiment of frater-
nifty which enables many different ma
tons and races to cooperate in its pro-
duction.-Baltimore Sun.