New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1899-03-12
WANTED, A NEW TELESCOPE.
PROFESSOR PICKERING WISHES TO MAKE 4
FRESH EXPERIMENT II CELL sTIAL
PHOTOGRAPHY.
PHOTOGRAPHY

PHOTOGRAPHY.
The kind or telescope that is used for photo
graphing the heavens is somewhat different from
that which is employed for visual work. The
curves OF the lenses are not quite the same. One
cannot see advanta geously with a Photographic
telescope. nor take pictures satisfactorily with
an instrument designed for observing.
There is another point OF dissimiiarity between
the two. The ratio between the diameter 'or
aperture) and length Of the instrument in the
ordinary telescope is one to fifteen or more.
The Lick and the Yerkes instruments are about
nineteen times as long as they are wide In
many. though not all Of the instruments now
doing Photographic work the length is much
less in proportion.
The Photographic telescope which Miss Cathe-
rine W Bruce. Of New-York City. provided for
Harvard 4 few years ago has an aperture OF -
inches and until very recently was the largest
instrument Of its special kind in the world. It's
length is only II feet. or six times the diameter
A great variety OF work has been done by the
Bruce telescope. and it has proved notable
success 1t has been especially useful in photo
graphing certain large objects like nebul9 and
the Magellanic clouds. short focus" tele-
scope. or camera covers a wider angle than a
long-focus glass. and a greater area can thus
be photographed. The existence Of extensive
nebuosities which would otherwise have been
overlooked has thus been detected.
Encouraged by the famous success Of the
Bruce telescope Professor Pickering. director Of
the Harvard astronomical observatory now
wants To try another experiment leading n the
opposite direction. He wishes TO haze an instru-
ment whose length shall be more than hun
drod times as great As its aperture-say 10 or
1872 feet long and having IN object glass only
10 or II inches in diameter. A. VIII readily be
perceived such an instrument would cover
much smaller area than even the ordinary OBJ
serving telescope. But the space which u did
cover would have its details delinoated with in
creased distinctness For special lin Of work
this quality would be immensely valuable
The result could not be doubtful Already
little has been done in this direction. For
yh0tographing the solar corona seen only during
a total eclipse II the sun. Professor Schaeberie.
Of Lick Observatory has tried q 3-inoh lens
ct at distance OF nearly hundred feet from
the sensitive plate Professor Pickering would
operate On large scale Resides. II he had
what he now asks for he would keep his appa-
ratus in almost constant use instead Of raserv-
ing it for rare occasions. There is fin chance
now for some publc-sprited person % adj
vance astronomical research in a new field by
giving him this glass. Between 5000 and
$4,000 is needed.
The difficulty Of mounting and keeping rieiily
straight in all positions a tube which is hfty
sixty feet long is 50 serious that the proposed
telescope would be arranged differently from the
ordinary observatory instrument It would
doubtless be stationary and horizontal and the
image which TO be photographed would be
reflected into it by means Of 4 mirror guided
by clockwork. This sort Of thing is oaled
heliostat OF sderostat