New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1907-03-03

win be kept wet Throughout the entire process
| Of polishing
The great mirror. together with its several
/ auxiliary refectOrs. win cost $4,000. and "a
| be the gift of John ID. Hooker. q DhiIanthropist
/ OF Los Angeles The construction OF the mount
inss of these mirrors viii require a year and a
special electric motor truck has been devised to
carry them To the summit OF Mount Wilson.
which rises to an altitude of more than a nile
above the nearby surface Of the Pacific.
The completed telescope viii have the power
| 70 bring the moons image within fifty miles Of
the earth. theoretically. An object on the moon
less than half as long as the Capitol at Wash
ington and less than third as high as the
Washington Monument should thus be discern
IbIe under the most favorable atmospheric con-
ditiOns- In other words. were our largest struct-
/ ures duplicated upon the moon they would he
perceptible. although probably not Recognizable.
| through the new telescope.
Although this powerful instrument may be
used to examine small objects uDOn the moon.
so enormous will be its Hght-gatherine power
that any attempt to reflect the full image Of the
moon into it's eyepiece would probably result in
permanently binding the astronomer who should
I observe it,
This. the greatest light gatherer ever designed
| by man. will be used upon the stars and ne5uIce.
/ the raw material out Of which the stars are
made II the full image Of the moon would blind
the observer at its eyepiece- that Of the sun
would utterly destroy the telescope itself Hence
the big reflector will be used only for night OBJ
servatiOn- Throughout each day refrigerating
plant will cool the great dOmed observatory in
| which il and its ffty-fOOt tube are to be stored
| and Will maintain them at the temperature q
the coolest hours OF the night. This will prevent
j the contraction and expansion Of the glass and
any consequent warping OF the image or crack
Ing of the siIvered surface
The most powerful telescope of to-day is that
at the Yerkes Observatory, with a lens forty
inches in diameter. But the Hooker reflector.
with its one hundred inches diameter, will have
for Photographic purposes light couectin,
power possibly ten times that of the Yerkcs
lens, 1t will also reach objects three times as
far away those reached by the Yerkes tele-
scope. and each heavenly body reached will be
shown with far greater detail
The advantages Of the reflector over the Iers
are thus very great Cheapness is one net to be
overlooked A lens equal In diameter TO the
hUndred-inch reflector would cost at least A
million dOIlars-if IL were possible 10 anneaI a
piece OF glass Of that size-whereas the re-
lector itself can be constructed for about one
twenty fifth that amount In the Yerkes tel
escope modern lenses are thought to have
reached their limit OF size, so far as usefulness
is concerned This is because there is greater
and greater loss OF light gathering power the
bigger a lens is made. No light passes through
the reflector, whereas all OF that concentrated
by a lens must pass through the glass. which
abSOrbs more and more of il the greater the
amount Of glass there is TO penetrate. A re-
fectOr brings all light OF whatever color to one
focus. whereas a lens focuses rays OF different
cOlOrs at different places
Why. then. have big rejecting telescopes not
been built before. il astronomers have realized
these many advantages? As matter OF fact.
two have been begun. As early as 1915 the
Irish Earl OF Rose manufactured. at Parson-
town, such a cOncave mirror. 6 feet or %
inches. in diameter But he was never able to
overcome the engineering difficulties OF suitably
mounting his reflector Astronomers generally
became discouraged at his failure and little
more was heard about giant rehectOrs until
about ten years ago. when Il was announced
that one of g. inches and another Of 81 inches
were being constructed for the projected Arneri-
can University at Washington and the Paris ex-
position, respectively But neither OF these was
ever mounted In q telescope. However the great
advantage Of the mirror over the lens has since