The Manitowoc pilot. [volume] (Manitowoc, Wis.) 1859-1932, 1886-12-09
manitomof pilot.
THURSDAY, DECEMBER 9, 1885,
THE GREAT TELESCOPE.
ARRANGEMENTS FOR SHIPPING THE 500,
600 LENSES DELICATE GRINDING.

| ARRANGEMENTS FOR SHIPPING THE Sop,
600 LENSES. DELICATE GRINDING.
Boston Transcript: The two great
lenses for the Lick telescope, on
which the Messers Clark, of Cam
bridge, have been so long at work, are
now practically completed and will
soon be sent to their destination.
The plan adopted for shipping the
double lens, worked out by Capt.
Frazer, is as follows: The two glass
es will first be wrapped separately
in fifteen or twenty thicknesses of
cloth drawn very tight. The cloth
will be cotton, and In order to make it
soft and perfectly free from grit it
will be washed many times and
thoroughly beaten. Next 20 the cloth
viii come thick layer of cotton bat
ting and then d layer OF paper. A
box made of wood and lined with felt
will contain the glasses when SO pre-
pared, the felt lining of the box com
ing next to the paper. The lenses
with their covering will be packed
tightly IN this box The shape of this
box will conform to the shape OF the
lenses. The felt will be attached with
glue, so that no nails will be anywhere
near the glass. Outside Of this wooden
box and enclosing it will be a strong
steel box, about the shape of cube.
The wooden box Will be tightly pack
ed into the steel box with curled hair
To enclose this steel box will be still
another steel box or chest, and the
inner steel box will be kept from
touching it by a large number of
spiral springs covering the whole in
terror Of the outer steel chest. The
outer chest will De packed with
asbestos, to render it freproof, and
both Of the steel boxes will be made
alright and waterproof The outer
chest Will be suspended by pivots IN
strong wooden frame, and a contrivance
has been adopted for turning the chest
one quarter around every day during
its progress to California. This is to
prevent any molecular disarrangement
in the glass and avoid the danger Of
polarization, it being feared that the
Earring of the train will disturb the
present arrangement of the molecules
unless the position of the glass is daily
changed and the lines Of disturbance
thus broken up. The glass will be in
sued for its full value-or rather its
cost $51, 900, and all the precautions
mentioned are taken to prevent any
accident to it. 1t would probably be
impossible to replace it, as Fell, who
cast it, and the elder Clark, who
ground it, are both old men. The
glass viii be shipped by express.
There is something almost romantic
in the design and construction of the
monster Lick telescope Being the
greatest work of the kind ever under
taken; presenting difficulties that had
never before encountered; inviting
and suffering drawbacks and disasters
that seemed to be sufficient to stagger
the most persistent and painstaking
skill; watched from day to day by
whole world of anxious observers;
lowered over and caressed by the
united wisdom of generatiOn-the
lens has come into the world with its
great cyclopean eye ready to pierce
the mysteries of the heavens. Capt.
Thomas Frazer, superintendent OF the
observatory, furnishes some hitherto
unpublished and highly interesting in
formation 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 measure at command
was the i10,000th part OF an inch; but
in grinding the great lens it was dis
covered that even this infinitesimal
fraction was too large. A still finer
measurement was required IN reduc
ing the lens in numberless places to
thickness itself unequal that would
exactly concentrate PARALLEL rays OF
light filling a circle three feet III di-
ameter to a point a little larger than
pin. In order to reduce the fine
measurement already at command
the following ingenious arrangement
was employed by Alvan Clark x Sons,
makers of the lans: A gas jet was
placed before a mirror, which sent the
rays of light through telescope to
the great lens, thus magnifying the
rays. The magnitied light, passing
tnfOuSn the great lens, was sui
further immensely magnitied. In this
way the least failure of the great lens
to concentrate perfectly was detected,
and there was also determined the
amount of glass in it, at any given
point, that had to be ground off III
order to secure a perfect focus. Thus
a measurement of the 5,000,000th part
Of an inch was secured. 1t took very
| little grinding to remove SO small a
thickness of glass from given point,
a gentle rubbing with the thumb being
sufficient. as the glass is softer than
| common window glass.