The Wellington enterprise. [volume] (Wellington, Ohio) 1867-188?, 1883-12-12
How Telescopes Are Made.

Prof J. K. Rees, of Columbia Col
lege. lectured last night in the hall of
the Packer Collegiats Institute, Brook
lyn. to an audience of about six hun ired
people. The subject of the lecture was
I" The Great Telesco. es of the World"
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 anil 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 minutely the process of
grinding the lenses. In America this 10
done by means of an iron polisl er, 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 a more uniform sur
face, but experience has demonstrated
that no lenses as yet made have given
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
tracting any notice, but at last the
merit Of his lenses was published by
English astronomers. Just before the
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 Dearborn Observato-
nv, of Chicago, where it now is. 1t is a
| singular fact that New York City, occu-
pying the commercial supremacy which
1t does, can not boast of anything in the
line of astronomical research; but II is
| hoped that In the near future some one
| will endow an observatory which will
be a monument more enduring to the
donors memory than the commonplace
4 successes of life. The views with which
the lecture was illustrated embraced
photographs of the primitive appliance,
of the Chaldean shepherds for deter
mining the equ;noxes, the telescopes o.
Galileo and Herschel, and Tyco Brahe',
observatory on the Island of Huen
! Among the famous modern instrument.
were shown the mammoth refractors il
the Naval Observatory at Princeton
College and the refectors at Paris anc
Melbourne. In conclusion the speaker
after ment oning the divided opinions
regarding the merits of refractors and
refiectors, said: "The future optician
who may discover the means of avoid
: ing the secondary observation an'
change of color. the present drawback
In refractors, will demonstrate the par
amount utility of the refractor, or III
| one who finds the way to provide agains
all atmospheric changes in the re.iec'o
may give the palm to that style of glans
but up to the present tine all practica
| tests have shown the superiority of tn
reflector for astronomical work" Prof
Rees was loudly applauded--M J
, Times