The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1897-02-21
Largest Telescope Yet-Twice the
Power and Size of the Yerkes-
Its Gigantic Lens to Be Made in
More Than 100 Sections.

new telescope has been ordered for
the astronomical observatory on Mt.
Lowe, near Pasadena. Cal, that will
not merely be twice the size and power
of the largest telescope now in exist
ence, but in its construction represents
such q radical departure that, If sue
cessful it win open a new epoch in
astronomy. Indeed, it is promised that
high power telescopes, ouch as now en-
tail the expenditure of hundreds of
thousands OF dollars, will become so
cheap that every high school and educa-
tional institution in the country might
afford to own one The basis for these
extraordinary predictions is the fact
that the new telescope for Mt. Lowe
Will be simply an asSemblage OF small
telescopes, which, in their combination,
will have the same power as an i'm
menSe glass of the same aggregate
objective AS every one is aware, the
cost Of a lens increases very rapidly
in proportion TO its size. The 42-inch
objective for the new Yerkes instru-
lnent, which has just been completed,
alone cost $4,000. cast in the rough
The grinding and polishing may have
cost twice as much more. Another fact
which is less understood is that the
large lens which forms the objective
of a telescope is not a magnifier, but
a light gatherer. The magnification OF
the image is done by the eye-piece. 1t
was this fact. set off against the i'm
mense cost of lenses of very great size
that led an ingenious German inventor.
now living in Chicago, to the idea that
instead of an objective being formed OF
a single large lens, he might make the
latter in sections, so to speak, and ac-
compish the same result, and even
much more.
To oil his id6Q
that he might take a quantity of small
lenses, say from three to six inches in
diameter. and assemble these in eX-
actly the same shape and curvature
as one lens. and so build telescope
of practically the size desired. He did
this successfully in a small instrument,
and now an order for an instrument
with an objective six feet in diameter
has been placed with him BIZ Pro-
lessor T. S. c. Lowe the founder of
Lowe observatory. At a first glance
it seems simply absurd to suppose that
a great lens made in sections with the
necessary breaks in between, would be
worth ANYTHING whatever, since the
casting, grinding and polishing of a
great lens like that in the Lick tele-
scope or for the new YerkeS observ-
atory, literally requires years of the
most patient and unremitting effort.
And even then there are often i'm
projections which make the instrument !
far from perfect. But, according to the
theory upon which the Lowe telescope |
is to be constructed if the substance |
which fills the interstices between the |
different lenses be opaque, and like |
wise OF such character as not to de- !
Velop the pTismatic colors, not only !
will the vision not be impeded in the /
least, but a great lens far more per- /
feet than OF any single glass may be !
built up in this way. In the casting of /
a large mass of glass. its imperfections |
become greater with the size, and the |
glass less clear. dense and homogen- /
eous This is owing to the fact that /
the exterior must necessarily cool first, |
and the interior molecules of the glass /
are then obliged to adjust themselves
to the exterior environment. If the
mass cools rapidly these intersections
are often so great as to make the cast
worthless Hence what is known as
the slow cooling process has been de-
vised But even with this. imDerfec-
tions still exist, which absorb and de-
fleet the rays of light, and so rob the
instrument OF perfect accUracv. Thus
an increase in the area OF the lens is
always at the expense Of density and
clearness. so that at a certain point the
ratio oc power TO area begins TO de-
cline RAPIDLY, until the limit is finally
reached.
So far as any man can now see this