Evening star. [volume] (Washington, D.C.) 1854-1972, 1931-06-14
SUPER7ELESCOPE
BEING BUILT HERE
.Savant Builds Device Here to
Photograph GaIaxies at
60 SextiIIion Miles.
Continued From First Page.)


Ritchey, tie co-inventor, now is at the
observatory experimenting the con-
struction. After designing some of the
most powerful telescopes in use in the
United States, in making observations
which In the last 20 years have revo-
lutionized the knowledge of astronomy,
Prof. Ritchey spent the last seven
years in France engaged in optical eX-
perimentS and in perfecting the de-
vices which are to be incorporated in
the new instrument.
This telescope is designed both for
visual and Photographic observations.
But its especial excellence, 1t is ex-
pected. will be realized in the latter
field. where the greatest advances are
being made in present day astronomy.
A telescope is focused on a section of
the sky. One plate can be exposed
night after night. Objects at the CEN
ter Of the field are photographed with
great clearness and detail. depending
on their prominence and distance.
Overcomes BIurring.
But with the older type instrument,
the images become blurred as the sides
of the field are approached Objects
no longer are shown distinctly and
many escape the picture altogether
Thus sky photographs show a thinning
out of small stars from the center to
the edges OF the field upon which the
telescope has been focused. This does
not mean that there are fewer of such
stars, but that the plate has not been
able to record them. A false impression
is given of the distribution of matter
in such field as a spiral system or
star cluster &. gs' 49,
BY an optical device which he in
vented jointly with M. Chretien of
France, which is being incorporated in
the new telescope, the edges of the field
will be shown about as clearly and in
as great detail as the center, Prof.
Ritchey says. This device consists of
an arrangement of a concave and a
convex mirror by. which the blurring
effect Is overcome.
Theoretically, Prof. Ritchey ex-
planned, a rejecting telescope should
times for each inch Of diameter of the
glass. Thus q 40-inch telescope should
give magnification of 1000 dame
tiers. It should make visible objects in
the heavens which are 1000 times as
faint as can be distinguished with the
naked eye. A celestial object, of
course, grows fainter with distance.
Applied to nearer objects in the heav-
ems, such as the moon and planets,
the instrument should reveal 1000
times as much detail.
Efficiency Lost in Size.
But, Prof. Ritchey explained, enor-
NOUS technical difficulties stand in the
way of realizing theoretical perfection,
especially in celestial photography
Generally speaking, the larger the
glass the greater the loss of eff
cheney, due to mechanical difficult
ties. Moreover. atmospheric condi-
tions seldom approach the ideal for
observation. So no Photographic tele-
proaches its theoretical range. But
the new instrument is expected to real
lie approximately 90 per cent of its
theoretical efficiency.
Prof. Ritchey was able to achieve
about 90 per cent of maximum theo-
retical effectiveness with 20-inch
telescope with which he worked in
France, designed Don the same con-
cave-convex mirror principle. The new
instrument will embody all the prin-
ciples employed in this 20-inch tele-
scope but will be twice as large.
With 60-inch instrument Of the
older type, which he constructed and
used at Mount Wilson, Calf, 20 years
ago, DR.. Ritchey was able to photograph
objects which, by calculations based On
their size as compared with similar OBJ
jects Of approximately known distance,
were 1900 times farther away than the
great spiral star system in the constel-
lation Andromeda. This star system is
approximately 10000, 000, 900, 600 900 900
miles from the earth-or the distance
that light, moving at approximately
1876, 900 miles a second, would traverse
in 100000 years.
Range Increased 1000 Times.
Now, Prof Ritchey explains. this 60
inch telescope was very far from SO per
graphic plate to catch the details of
the field upon which it was focused.
The new instrument will not be as large,
but 1t will embody so many technical
refinementS that an estimate OF range
1000 times greater than the distance to
the great Andromeda spiral is consid-
cred conservative.
Much of the improvement, Prof.
Rltchey expects, will come from photo
graphic plates Of new kind upon which
he has done much experimental work
during his Sojourn in France. Under
his system practically as much atten-
ticn is paid to the perfection of the
glass plate as to the telescope itself.
Prof. Ritchey Is working on the
principle that much more can be ac-
complished in astronomy by getting the
most possible from smaller-sized in
str1lments than by building telescopes
Of greater and greater diameter with
cut perfeeting the minute details upon
which good observation and photo-
graphic work depend. Many of the
improvements he Is incorporating de-
pend upon intricate optical principles.
May Reveal New Worlds.
But, Prof. RItchey explains, the new
type OF telescope is not limited in size,
and even 26-foot instrument en-
hoS9ano TIA eay va t1rf,s eiYalne Ga YNneeI1alo