The Kenosha telegraph. [volume] (Kenosha, Wis.) 1860-1888, 1883-11-23
How Telescopes Are Made.

Prof. j. X. Rees, of Columbia Col,
lege, lectured last night in the hall of
the Packer Collegiate Institute, Brook
Ign, to an audience of about six hundred
people. The subject of the lecture was
1.-The Great Telescopes of the World,n
and it was illustrated with dissolving
views. The professor read from manu-
script in an easy and clear voice, and
dressed his thoughts in simple and ap-
propriate language, using but very few
technical terms. He began with a de-
scription of the manufacture of the diff
ferent parts Of the modern telescope,
describing infinitely the process of
grinding the lenses. In America this is
done by means of an iron polisher, made
to fit the convex of the lens as near as
possible. The inside Of this polishing
iron is coated with pitch, and the glass.
having been first roughly ground, is
placed inside, and the workman walks
around the polisher pressing on the
lens. In Europe the polishing is done
by machinery, the lens being held
against the revolving polisher. This, it
is claimed, insures more uniform sur
face, but experience has demonstrated
that no lenses as yet made have oiven
such general satisfaction as those ground
by Alvin Clark, of Cambridge, Mass.
and all glasses from him are ground by
hand. 1t seems singular, thinking Of
the fame that this man now enjoys, that
it was in another country he first gained
a reputation for fine work Alvin Clark
was portrait-painter, and took up the
study of optics as diversion. For ten
years he turned out glasses without at
tracing any notice, but at last the
merit OF his lenses was published by
English astronomers. just before the
outbreak of the war, Prof Bernard,
now President of Columbia COLLEGE
and then the head of the University of
Mississippi, gave Alvin Clark an order
for lens fifteen inches in diameter.
The rebellion prevented the sending of
the glass to Mississippi, and finally it
was bought for the.pearborn Observable
ry, of Chicago, where it now is. 1t is a
singular fact that New York CITY, occu-
plying the commercial supremacy which
it does, can not boast of ANYTHING in the
line of astronomical research; but it is
nOpON unAb III tu0 uOttI luGuT0 some one
will endow an observatory which will
be monument more enduring to the
donors memory than the commonplace
successes of life. The views with which
the lecture was illustrated embraced
photographs of the primitive appliances
of the Chaldean shepherds for deter
mining the equinoxes, the telescopes of
Calico and Herschel, and Tyco Brahe's
observatory on the Island of Huen.
Among the famous modern instruments
were shown the mammoth refractors in
the Navel Observatory at Princeton
College and the rehectors at Paris and
Melbourne. In conclusion the speaker,
after mentioning the divided opinions
regarding the merits of refractors and
retfectors, said: "The future optician
who may discover the means of avoid
ing the secondary observation and
change of color, the present drawbacks
in refractors, will demonstrate the par
amount utility of the refractor, or the
one who finds the way to provide against
all atmospheric changes in the reflector
may give the palm to that style of glass.
but up to the present time all practical
tests have shown the superiority of the
refra ctor for astronomical work. Prof.
hess was loudly agplapded, IN II
Times, 81