The Daily times. [volume] (Richmond, Va.) 1886-1889, 1886-12-29
THE GREAT LENS.
CONS TRUCTING THE BIG TELESCOPE
FOR THE LICK OBSERVATORY.

The Most Difficult Work of the kind
Ever Undertal<cn--siighly Interesting
MISUNDERSTANDING the Double Lens
to san Trancisco.
Mr. Jaules Lick, It vii bc remembered,
left 500, 900 for tho erection OF az observe
tory, and Mount Hamilton OF The Pacific
coast range was chosen as Offering the
greatest convenient elevation. The loca-
ton is in Santa Clara county, thirteen miles
from San Jose, viii which city teicphonic
communication has boon established Mount
Hamilton is tri-mountail, the highest
peak rising 4, 500 feet The sOulr "a peak.
tie site Of the observe Dry, is about 12j
fcc5 lower than tho northern, blt WAS chosen
on account Of its easy accc 5iity Tho
plateau upon which tho buildings stand IS
about $50 feet IL length, vi,l a breadth Of
22j feet. Tho LARGEST telescope in the
world viii be used here. Ther1 is some
thing almost romantic IL the design and
construction of this monster telescope.
Being the greatest work of the kind ever
undertaken, presenting difficulties that had
never before been encountered, its manu-
facture has been watched from day TO day
by whole world Of anxious Observers.
SOME INTERESTING DETAILS.
Capt. Thomas Fraser, superintendent Of
the observatory furnishes some definite and
highly Interesting information concerning
the grinding of the crown glass lens and the
plan adopted for Transporting it from Cam
bridgeport, Mass, to San Jose. On the
subject Of the grinding. he says that the
closest measurement at command yGS the
10,C00th part Of an inch but in grinding
the great lens it was discovered thar even
this infnitesimal fraction was too large.
still finer measurement was required in re-
ducing the lens IN numbor,.ss pieces %
thickness Gtself uncquaD thot would c-lctly
concentrate parallel rays Of light filing
circle three feet in diameter TO a point lit
tie larger than pin
in order TO reduce tho iine measurement
already 1t command The following inGen-
ious arrangement was employed by Clark
6 Cons. ma'ioIs of the Ions: = gas 5ct Tos
placed before q mirror, wiich aanJ TIE rays
Of light through a telescope 30 tho great
lens thus maor.fying the rays. The mag
nifed Lent. passing through the great lens,
after having passed Trough tins ins II
vas observed through second telescope,
and thus further magniiied. Iva ths way
;hc least failure OF the great lens 10 conccn-
.IGte perfectly was detected, aud there vas
also determined the amount of glass in 1t ot
qny given poiay that had 10 b. ground or
in order to secure "a perfect focus. Ihas a
measurement Of ,, 900, 0UOth part Oh an inch
was secured IL took very little grinding
to remove so small thickness of glass from
q given point, gentle rubbing with the
thumb being sufficient, IS the glass Is softer
than common window glass.
SHIPPING THE DOUBLE LENa.
The plan adopted for shipping the double
lens to San Francisco Is as follows; The two
classes wero first wrapped separately IN
fifteen or twenty thicl1lesses OF cloth q avn
very tight. The cloth is cotton, and IN
order to make it soft and perfectly free
from grit. it was washed many times and
thoroughly beaten. Next to the cloth
come a thick layer of cotton batting and
then a laver of paper. A box made of wood
lined with felt contains the & lasses when so
prepared, the felt lining of the box coming
next to the paper The lenses with their
covering are packed tightly in this box. The
shape of this box conforms to the shape OF
the lenses. The felt is attached with glue,
so that no nails are anywhere near the gia's
Outside Of this wooden box and inclosing
il is a strong steel box almost tho shape OF
q cube. The wooden box il tightly packed
into the steel box with cnrled hair.
Still another steel box or chest mcloSer
the steel box first named and the inner steel
box is to be kept from touching it 10y large
number of spiral springs covering the whole
interior of the outer steel chest. The outer
chest is packed with asbestos, TO render Il
lireDroof, and both of the steel boxes are
made alright and waterproof. This outer
chest will be suspended by piyots in n stronS
wooden frame, and contriyance has Been
adopted for turning the chest one-quarter
around every day Turing its progress to
California This is 10 prevent any moiec-
ular disarrangement in the qiaso ANA avcii
the DANCER OF polarization. The glass J.
insured for its full value-or, rather, It's
cost 81. 000-Frank Leslie's.