The Wichita daily eagle. [volume] (Wichita, Kan.) 1890-1906, 1897-05-22
Biggest in the World.

pdtIoT Car from the OidIkS lens WOIkS N
Cambridge the other day to Chicago.
These disks. which form the lens for the
Yerkes telescope, are the largest ever made.
and with their aid the astronomers look
for most starting discoveries. some even
predicting that the works Of human being
VIII be detected on Mars
They were transferred in their cases to
the parIor car IN the rear Of the lens works
ed into Boston and attached the 7:l5 p. m.
Chicago express.
Professor Alvan G. Clark. the maker Of
the lens: Carl A. r. Lundin. his foreman.
who has spent several years IN polishing
the great lens accompanied the valuable
cargo. The greatest care was taken that
no harm befall tie TWO disks, and in their
large cases in the center Of the car they
were so adjusted on springs that the jolt
ing could not damage them. Guards were
stationed at both doors Of the car, and
every precaution taken that outsiders and
curious seekers should not in any way In
terfere with the transfer Of the lens. Then.
too. they were insured for their full value
while in transit
This Yerkes tense Is the largest and finest
in the world. II represents nearly six years
Of careful labor, and completed is valued
at $4,000. The glass came from the fac
tory Of Mantois. in Paris. France. in May.
1882 and its cost IN the rough was 10000,
and for the painstaking work OF grinding
and polishing Mr. Clark received 1000.
the work taking the larger part Of the 1--WE
years IL has been in the factory at Cam
bridge. The lens has been completed and
awaiting shipment many months. the de-
lay being due to the fact that the observa-
tory built by c. T. Yerkes. the purchaser
Of the lens, near lake Geneva, Wis, was
not in readiness to receive it.
The lens Is Hh inches on the surface da-
meter and weighs SIS pounds. The expos
ed surface or aperture is 10 inches, the
other inch and half bein gtaken up by
the casing. This makes It just four inches
larger than the Lick telescope lens. which
was also made by the Clarks, and which
has held the place Of honor in the world Of
astronomy.
This great lens consists OF two separate
lenses CT differing density and shape, sspa-
rated when in use by a space Of several
inches. The outer one. which comes in
contact with the atmosphere, Is made Of a
perfect piece Of crown glass. 1t 10 double
convex, z& inches thick at the center and
:. of an inch thick at the edge. and weighs
205 pounds. The inner lene is made Of hint
glass. and u what 10 known as piano con-
cave. II is Ia inches in thickness at the
center and inches at the edge. 1t weighs
80 pounds.
The packing of the tense was one Of the
most interesting features in their history.
and 1t was completed on Saturday. First.
they were carefully and smoothly wrapped
in flannel. sewed tightly at the edges. Then
they were covered with several thicknesses
of soft tissue paper, and then wrapped In
hard paper. and encased In a bed OF cotton
batting. silk and curled hair In a strong.
yet handsomely finished box. This box
was mounted upon springs, and placed with
in larger box and packed with excelsior.
TIL. springs within the outer casing. be-
tween that and the inner box. are designed
to detract from any jar that the outer case
may sustain, and thus save the lens from
the effects Of almost any shock.
The great glass disks for these lens were
cast in Paris, and a year was taken up In
the material and casting q dozen
or more before a perfect one was secured.
Even then II had to be cut and recut before
oil the air bubbles and Inequalities were
carved out of it. When they arrived a,
the ClarkS' works they were rough and
crude, with very little shape to them.
The care the skill, the patience which
have been expended in grinding the lenses
Is marvellous. There Is very little machinery
about 1t and no secrets. And yet there
are few men in the world who have made
a success at it--none in fact who have earn
ed a reputation Ike the Clarks, Of whom
there Is only one left. Professor Alcan G.,
the maker Of the largest lens in the world.
;e Ips0 fhA =: lob
est form Of handicraft. and patience Is the
main factor TO success.
When the glass was received II was first
tested for strlae. 1t was set on edge mid
way Of long, dark room, with a light at
one end and the examiner at the other. |
An assistant held a tense between the light
and the disk and the rays as they were in
tensified upon the disk nAgnsfied any i'm |
PROJECTIONS. The glass was next tested Tor !
polar.zed Eight. being viewed in the outer |
light through revolving nico! prism. Hav-
Ing stood these tests the glass was ready to |
be shaped. |
The two essential things at the outset IN |
making a telescope lense are the specifica. |
lions OF the diameter and length of focus |
The problem is to determine what curve to |
give the glass In order that every ray OF |
light which strikes the specified surface |
may be refracted 10 a common point at |
precisely the required focal distance. Then |
the lens underwent the process of shaping. |
being ground on steel crushings between |
ron and steel mods, which reyolved with |
IN eccentric motion, and then on 10 courses |
IF fine emery, until 1t assumed approx |
nately its proper form.
II was at this stage that tie finest and I
most difficult work on the lens began, and !
n taking measurements an instrument was |
used which through the microscope meas
ires 1-s0-1oo0th of an inch. The final shap- 1
ng and polishing were done with beeswax
by hand-a Job that required months of |
line and patience beyond estimate.
When completed last fall the lens was
mounted In temporary telescope tube and |
ested for 50 nights. and found perfect.
Had there been a deviation OF SPIDERS
strand IL would have been useless. and
piders strand Is as much smaller than a
human hair as a human hair is smaller
han a telegraph pole With even one
pot or bubble In the glass as small is the
,oint OF a pin the largest celestial bodies
would be hidden behind IL. While Mr.
Clark and mis- assistants hev. not worked
upon these lenses since they
we're received in Cambridge. five years ago,
ret there has been little time when some
hing was not being done in perfec'ing
hem, and they have been watched as close
Y as a sub-Ceasury vault They have
'een kept at nigh, in a hreproof brick an
lex 20 the works. and a Waterman was at
II times. both day ami night, IN close proxi-
nifty.
The largest telescopes IN the order o.
her size. ali Of which we're made a. the
'iarks' works are: Yerkss. Geneva. VS.,
o-isch clear; Lick observatory. Mt Hamil-
On Cal. ss-lnch: Russian government. Pul-
owz, S-inch; University Of Virginia, Char
Va, es-inch. Bruce photographs