New-York tribune., 1901-10-13

Astronomers use the rejecting telescope very
little for visual work. but find it an excellent
resource for photography. which now forms
such important element in stellar science.
Shortly before his death Professor James e.
Keeler getting some notably good pictures
of nebulae at the Lick Observatory. in CALI
fornia, with the Crossley reflector. which
presented to that institution eight or ten years
ago. but was not in very good working order
at first. Indeed, even after undergoing repairs
it still had annoying eccentricities. and the
suits which Professor Keeler obtained were the
more remarkable that account.
Within q few weeks long projected reflect
ing telescope for the YerkeS Observatory, at
Williams Bay, Wis. has been completed and
put into service This has a mirror twenty-fsur
inches in diameter. and focal length of eight
feet. The Cross,ey reflector has diameter Of
| thirty inches. but in other respects the di-
| rector Of the Yerkes Observatory. Professor
| George E. Hale. is inclined to regard his in
strument superior to T. The mounting is
exceedingly rigid. and the gearing. by means Of
which the clock enables the glass to follow a
celestial object automatically is exceptionally
uniform and accurate. Thus anything like wab-
bling elasticity is precIuded and the image
Is kept upon exactly the same part of the field
of view. When one remembers that the struct-
ure of nebula is sometimes almost as delicate
[ as q cirrus CIOuQ, ana JnaI q pnOtOSIdpIuc
plate must often be exposed for hours in order
10 register faint details. he VIII perceive how
necessary it is that Photographic telescope
shall follow with great precision. Yet the
most trihinS inequality in the Coss which move
it viii shift the image first to one side and
then to the other Professor Hale remarked
the other day. while in town, that the mount
ins seemed TO him fully as important as the
mirror. He exhibited several specimens of
work done by the new instrument 70 justify his
admiration.
Several of these were photographs of well
known nebulse. one was the famous spiral
nebula in Canes Venatici Another was the
much bigger and even more instructive cloud OF
dust or gas in Andromeda. ROberts's now cele-
trateG picture Of the latter created great
sensation fifteen or twenty years ago. because
il brought out details never detected visualy
with the telescope. and showed that the An
dromeda nebula is a giant whirl. which is ap-
parently breaking up into coneentrc rings
From casual inspection Of the Yerkes photo
graph it would appear that more Of those
fine but significant wisps OF cloud have ucen
registered therein than the Roberts picture
contains. The sharpness with which minutiee
are revealed on these plates is a gratifying as
surance of the quality of work 10 he eXPe ted
from the reflector in the future.
Already. however. the new telescope has en-
ing discovery. Several months ago Camille
FIanmarion, the French astronomer. suggested
the possibility that the star which appeared
in Perseus last February might have nebuIous
Envelope. Following what is now well established
precedent. Nova Persei assumed the appear-
ance II Planetary nebula'' several months dSos
after undergoing many fluctuations of brightness
and spectrum. y planetary nebUla is supposed
to be substantially Identical in composition with
gaseous nebulse but il is very small and round,
and has measurable diameter. The planets
possess this last characteristics but not the stars.
Even i'll the most powerful telescope star pre-
sents only point. not disk. But what NJ
F!ammarion had in mind the possibility
that there might be halo. corona, or en-
velope of irregular shape and much more attenu-
ated substance lying we'll outside the periphery
of the disk. He suggested to Professor Wolf, Of
Heidelberg, that he try TO get picture of the
Nova in order TO test the validity of the sus-
picon. Professor Wolf is a leading expert In
celestial photography. and has made q specially.
like Professor Barnard. of this country. of small.
faint nebule.
The German tried. but got an indecisive result.
His plate exhibited a little streakinesS. but this
was not enough prove anything Then, at
Professor Hale's suggestion. Mr.. Ritchey. of the
Yerkes Observatory. tried the experiment, using
for that purpose the new reflector The attempt
was made on the night of September 20. and the