New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1898-03-13
PHOTOGRAPHS OF NEBULAE.
ANOTHER STEP TAKEN IN ASTRONOMI-
CAL RESEARCH
H. nAHOURDIN A FRENCTiMAN. EXTENDS THE
POSSIBILITIES OF sTUDY-A ''SHoRT
FOCUS" EEFIEcTOR GIVES GRAFT
FLYING RESULTS.
FLYING RESULTS.

v~arch. no such advances have been maze III any
branch Of astronomical work during the last he"
years as in photography. and no class OIL SUI
jerts has received attention from the
camera Of late than those enormous but ex-
ccedingly delicate clouds of dust and gas, the
nebula.-thc ray material out of which the
astronomers are inclined TO believe. suns and
worlds are being made.
Some OF these beautiful sheets and sprays OF
celestial gauze were known before the apphca-
tion Of the modern system Of self registration
to them: and yet it has frequently happened
that their extent was considerably increased
and their outlines surprisingly altered when
tn, camera was directed to them Their photo
crlphs sometimes differ so much from the draw
ings which skilled observers. like Sir John
Hcrschel and the elder and younger Bond have
made hat the resemblance car scarcely be de-
tectcd
So,ne now and interesting pictures OF ncbulr
have recently been reported from France Tie
Hrnry brothers at the Paris Observatory are
alrrady famous for some exquisite photographs
CT the ncbul9 which seems to include the whole
PI.iades group But the Meu1on Observatory,
presided over by n. Jansen, has hitherto been
devoted almost exclusively to solar research
II nov appears that NJ. Rabourdn. an attache
Of the latter institution has boon working OF
HcGectng telescopes have been used by Com
mon Roberts and others for Photographic pur-
poses but the curvature of the mirrors en-
rioycd was so slight Us to give a moderately
gr,It focal length But where rcfractor5 are
thu. used it has been found advantageous To
shorten the focus. In instruments for purely
visual work The proportion of the length u the
TUE to the diameter Of the object glass has
usually been about fourteen even ninctccn) to
one. whereas the Bruce Photographic tcc-
scope. belonging to Harvard and now in service
at Arequipa, Peru. is only about five ana a half
times as long as il is broad. Some of the por
trait lenses used for celestial photography have a
Sill! smaller ratio. Now. NJ. Rabourdin has pre-
ferrcI The rejecting telescope for his interest
Ing experiments at Meudon, but he has fol-
lowed the example OF recent designers Of pho
t0graphic refractors in one important respect
The diameter Of his mirror is a metre-very
nearly forty nches-but its focal length is only
three metres In consequence. his instrument
worked with remarkable rapidity.
NJ Rabourdn. for instance. announces that in
a sing hour he obtained 4 photograph of the
nebula in Andromeda that was az complete in
detail that which Roberts spent four
hours With the Plcades he seems % have had
even better su cess He exposed his plate only
one hour, just quarter OF the time which the
Henry brothers used; and his picture reveals
patches and streams Of nebuous matter which
are / OF visible III the justly admired photograph
OF his Compatrots
the astronomical world will be delighted at
this extension OF the possibilities of acquiring
knowledge in regard 10 nebul;e: for the mystcri-
Gus process by which the stars have been made
In the long lapse Of ages. out of this fimy stuff
Is one which mon have been sngul1rly eager to
learn. They have been very hopeful too. OF
success in that dire ton Photography has
considerably extended the frontier Of science far
into The unknown; and, notably in the Plciades. |
Orion and the Milky Way it is beginning TO |
suggest II not i prove. Intimate relationship |
betNeon special otbs ard streaks of ncbulous
matter that the tclascop, alone never revealed /
to mortal eye. But even photography has its |
limit What it is it is net yet safe to say
Scarcely year ago Dr. Roberts, famous |
English astronomical photographer. expressed |
4 fear that the limit had already been reached |
lie remarked that even in the dearest atmos-
phere. and with the blacklist background to the |
stars. there nevertheless an amount Of diff
fused light that would eventually fog" the
sensitv" plate after certain length Of time
and thus destroy the contrast Of light and shade
necessary in TIE delineation Of nebul9 No
doubt he is partially right: but, quite aside
from striking arguments offered by Professor
Wadsw0rth. II tile Yerkes Observatory the
achievements Of NJ. RaboIrdin show that men
may so a good deal further in this kind Of In
vastigatOn than had been supposed
L1p'1ce's ia Dry il regard TO the creation of
suns and satellites, in A modified form. is still
flvoTably regard d by astronomers. 1t offers a
better explanation Of the mode Of planetary Gre