The Bossier banner., 1892-03-17
STARS BEYOND SIGHT.
Tho Importance of the Photographic Plnre
in AStronOmy.

Tho Importance of the Photographic Pine
in Astronomy.
When the air is damp and warm
new iron surface will corrode very
quickly. Exposure for single day is
enough to mark nail here and there
with spec1s of rust, easily removed by
touch. However closely one might
observe the nail from the first moment
of its exposure, it would be impossible
to see the change taking place in it's
color The eye would tire of watching
long before a grain of rust would come
into view. An example this of count
less forces of nature, too gradual in
their activity to come within the limits
during which the eye can sustain its at
tention. They require time, and often
a very long time.
Now, if instead of the eye, so feeble
and SO easily fatigued, we have some
thing more sensitive to light and not
subject to weariness we can at once in
directly and very greatly extend the
field of human vision. Such a substi
tute is found in the Photographic plate
when it is treated with newly devised
compounds, upon which rays too faint
to be otherwise detected can imprint
themselves.
Besides its exquisite responsiveness
to light, this plate has another advan-
tage over the eye. We may look direct
ly at distant star but if it's ray is too
weak to excite vision, our gaze is in
vain, no matter how long we may be
able to maintain it. Not so with the
plate. The rays which fall upon it,
however faint they may be, steadily in
crease their effect from minute to min
ute, from hour to hour, until at last
they yield perfect distinct image.
All this has been applied in wonder
full way to the study of the heavens.
With every successive improvement in
the power of telescopes, astronomers
have brought into their ken nebulR
| and stars before unseen.
They know that invisible stars must
| far outnumber the visible ones, for the
| whole volume of starlight is much
| greater than the beams received from
| the stars within the telescopes range.
| Their belief, based upon past observa-
| ton, is that space beyond vision is ever
| ready to reveal a new wealth of worlds
| to any new power of exploration.
Precisely such a power is conferred
| by the sensitive plate just described.
| When it is attached to a telescope,
| whose lenses are by suitable mechanism
| kept constantly directed at a particular
| point in the sky, the astronomer is able
vastly to extend the diameter of the
| visible universe. Orbs so remote, or SO
| feeble in their ray, as to be invisible to
| the keenest observer, in the course of a
| clear night form well-defned picture
| in the camera.
| This noblest use of light as a limner
| has brought to view sphere of crea-
tion which no mortal eye shall ever di-
rectly see. sphere thickly gemmed with
stars, and stars in the making-as we
| now know nebulse to be. .
| BY subdivision of the heavens
among the worlds chief observatories,
comprehensive mapping of the skies
is now in progress. 1t will be much
more accurate and full than any previ-
Gus work of the kind.
In securing pictures of particular
heavenly bodies, photography is quite
as important as in making charts of the
stars. Prof E. s. Holden. who has
charge of the great Lick telescope at
Mount Hamilton, California, declares
| that the camera in forty minutes has
| given him as much knowledge of the
moons surface as he has been able tc
obtain in four years observation.
The satellite of Neptune, though in
| visible in the telescope on account OF
| it's proximity to thes planet, has been
| photographed in every part of its orbit.
What wielder of the pencil or the
brush would have dared to transfer the
4 suns lineaments to paper or canvas? L
was reserved for the photographer by
fine stretch of audacity, to compel tht
sun to take his own portrait, and to dc
| it in the fraction of a second. outh'!
| COMPANION. ....a p