Idaho semi-weekly world. [volume] (Idaho City, Idaho Territory) 1875-1908, 1890-10-24
A BIG TELESCOPE LENS.
The Great Lick Instrument Not Large
Enourh--A Delicate Undertaking.

The other afternoon Mr.. Alvin Clark,
the manufacturer of the great Lick tele-
scope lens, received letter from the
president of the University of Southern
California, located at Los Angeles, ask
ing for information as to forty inch
lens, and intimating that an order for
telescope to eclipse that at the Lick OBJ
servatory would soon be sent.
A correspondent who was present
turned his attention TO the numerous
lenses Of different sizes and in various
stages Of manufacture while Mr.. Clark
was reading the letter. He had just
been talking with the man who had made
eyes that could read patent medicine
signs on the moons rocks with regard to
the possibility for further advance in as
Economical researches, and he feared the
letter might make it necessary to shorten
his visit. Mr.. Clark's eyes twinkled as
he read the letter. Then, without a
word Of comment, he handed the missive
to the reporter and resumed the patient
rub, rub, rub of small lens glass ON the
polishing block.
'What do you think Of thatT' he
asked, when the reporter had made a
careful mental note Of the contents Of the
letter.
II thought 1t had been stated by some
savants that it was impossible to finish a
lens any larger in diameter than that
sent to the Lick observatory" the repor-
ter said.
IL know such a statement has been
made" replied Mr.. Clark, .'but do not
indorse it. I've been making telescope
lenses now for good many years, and /
ought TO know something about it, II
can get the glass the proper size there
will be no trouble in making lens forty
inches in diameter. I'd make a five
footer IL my life was spared long enough"
do you mean to say that there is a
possibility in the future of having tele-
scopes five feet in diameter2'
II don't see why they should not be as
large as that. But mind you, it would
take about one mans lifetime to make
such lens. In the first place, it would
he necessary to get piece of glass alb
solutely perfect in every way. The
slightest flaw or variation in density
would spoil it for big lens. 1t might
be generation before such a piece of
glass could be manufactured. Then it
must be ground and polished by hand.
But believe such lens can be made,
and l believe il will be made"
''Will it be Of any practical advantage
to astronomers?'
Certainly it will. Its increased mag
nifying power will be in proportion to its
increased sized. Take this forty inch
lens that has been mentioned as an ex-
| ar,pia ITO ci1a xrD,,Id ha ono mint I,
larger than the Lick observatory lens,
and it would make given objects appear
nine times larger or nine times nearer.
Increase the diameter of the lens and you
will increase the power to examine
worlds that have not yet been seen. II
lens five feet in diameter is secured it
will bring the moon so close that we can
see every nook and Granny ON its surface.
/ AS for new stars, there is no limit to the
discoveries that could be made. 1t would
revolutionize astronomical researches. 4"
"Had you thought of making a larger
lens than that in the Lick telescope before
you received this letter."
"Oh, yes. am not surprised at re-
ceiving this letter, for when | was in
California a year ago the president of that
university intimated that they should
want larger telescope than that on
Mount Hamilton. There is wonderful
amount of interest in astronomy in Cali
fornia. All sorts of people are studying
the science. This five inch lens | an
polishing is for telescope am making
for the president of that university. 1T
for his personal use, and he begged me
to make it with my own hands, so am
pegging away at it when | get the time.
have also filed other small orders from
that state. In addition to those small orders
l have received no less than three letters
from different colleges asking if | coulc
make forty inch lens. | have written al
those persons that was ready to accept
any and all orders for a forty inch lens
In fact, | was SO sure that there would b,
demand for such lens that gave oil
order to the glass men in Paris to save
for me the first large mold that they sue
ceeded in getting out. | may get it in {
few weeks and / may have to wal
months and weeks for it. heard The
other day that they hal cut out two
extra large plates and were finishing
them for the exhibition next year. i
it's true, l shall secure them if money
viii do it,"
"What causes this delay?"
at is all in the casting, was the reply
"All these lenses are made in France
near Paris. They are making them al
the time. They melt upa lot of glass
and when it is Of the right consistenc,
they set it aside to cool. The glass i
melted in huge pots, and after every
casting the pots are broken away, leaving
a large mass of glass. Then they examin,
it and test it to see if it is suitable to spill
up into lenses. 1t must be just right o.
1t must be melted over. They have order
for all sizes of lens, but they do not con
slider those orders until they get the blocl
Of glass. The least indication of strioe O.
sediment will show that it cannot be use,
for larger lenses. Then they break it III
TO sec II they can use it for small ones
There arc generally enough imperfection
to ruin the block for large lenses. II nom
Is visible to the eye the block is testet
with the polariscope, to see II 1t is of ever
density throughout. II oil the condition
are perfect. then they will split up tn
block and get out large lens in tn
rough. II they succeed in doing tina
there is still great danger that it win b
broken in the first handling to get it dow
to the proper aize for grinding and polish
ing. After that is accomplished the wors
danger Of breakage is passed, though O
course 1t would require the utmost skill
and caution not to break it while putting
on the finishing touches"
''Do you break many2n
Lots of them. We do not break q
many now as we did at first, but in III
I rOIlrsa Of n ypnr ct,,arh q r,o<,,l ,,,o,v