The Seattle post-intelligencer. [volume] (Seattle, Wash. Terr. [Wash.]) 1888-1914, 1899-08-13

81 ossk With I polasa 81 Ase rosUs. rubbed
around the disks with delicate alumsnum
took. But the mai polfAhIng 81 the 911sg
Was with the hand. II the blocks OF glass
had be<n abeolafely perfect TIE ps0beeA
would have been the shaping Of an exact
y co6cave, convex. and Daane SURFACE.
These. nicely adjusted. would have brought
every my of hight p = sing.e pstnt. But
no perfect block OF glass wa ever cast
Minute inequalities OF the inner texture
Minute ineQualities OF the inner te1tute 60.
ne~ae04ly must be counteracted ~ epnaHy
nn1auee depresslons and elevations - IN
surface. Carefully testing results ~ evesE
sep the whole surface ~ each lens v1D
rubbed and pui1ed into shape with the H.
ger tips when compaeted the polish vs.
So equisite that . teuch Uith warm fin-
glass and c4use temporary alteration OF
the rays Of light falling through the lens.
The constant cleaning and pol shing 81
this object eIhSs must be the work Of one
astronomer?" said thu rspefter.
On the csatrary.' rephed = professor.
"the glasses are too rreciOus T. be washed
oftenex than snee In yeafs."
The end a. the Telescope - peUtetted -
much as possible against wind and dust,
ard the Lenses are not cleaned at ALL Such
dirt as does accumulate settles evenly ovee
the enrfaee and y allowed 70 remain fef
n Ioag rs possible. when the gsa1U Ii
cleaned aicehel VIII be allowed TO pour over
II WITH scarcely pefceptsble spe<d with the
entire suef&ce b thoroughly soa1sd. The
dirt will then Be ptshet. ahead Of bit OF
absorbent cotton very gently and slowly.
This is the story Of the central feature
Of the Yerkes telescope. the monster eye,
the most magnificent optical nlase knoWn
10 man.
1t may be that another such perfect
glass will never De made. The secret Of
the polishing has been HANGED down for
three generations in the Clark family.
Previous to the work OF the Clarks Ger.
man fam.,y--the Fraaenhofers--had polisA-
cd these glasses For a century sitter the
death Of the last Frauenhofer II seemed
that The art Of polishing optical glasses was
lost Then AVIAN Clark. portrait painter
In Maeeac husetts. attracted the attention
of English scientists. and he and his fam
lily far excelled the German artists in
glass. Mr.. Avian G. Clark, tie Mst Of his
family, attended the dedication exercises
OF the Yerkes glass. returned u HE home.
and diec within few days
Good View a he Moent
The eye piece OF telescope. through
which the observer looks. is the part Of
the instrument which magnifies the OBJ
jects seen. The number of diameters to
which an object can be nlagnified to adj
vantage depends largely upon the perfec-
non or the object glass. In the Yerkes
telescape a glass which magn:fies 3.70o
times has been employed successfully.
Through this glass the moon would Ap-
pear - II would to the naked eye at .
distance Of sixty-four miles. The eye
piece ordinarily used magnifies 400 diam
eters. In illustrating the uses Of the var
ions eye pieces Professor Barnard screw
ed q small glass into an instrument
fastened to the end OF the big refractor.
"what do you see?" Ne asked as the
reporter sazed into the end Of the teie-
scope.
"weIl, see disk cut into quarters by
two small threads that cross each other
at right angles
The professor turned a little screw.
NOW the vertical thread has separated;
there are two, a little distance apart"
quite right" said the PROFESSOR sml-
ing. Those threads are cobwebs. They
are used to compute the motions Of
worlds and the distances OF the stellar
universe
Incredible as 1t seems, the delicate
measurements OF the movements OF the
stars are calculated by cobwebs nicely
stretched and forming the real measuring
apparatus Of the n1icfometeP. They last
for years and are even cleaned Of dust
with a delicate camel s-hatr brush. TAX
Ing on the glass covering one evening.
Professor Burnham was examining the
webs. He Systematically breathed into
the aperture, breaking one OF the fla
ments, which It took considerable trouble
to replace. At the Yerkes telescope a de-
vice has been perfected for lighting the
threads with electricity and making them
a faint red color. A white light on them
would be 80 brilliant as to injure the eye
OF the observer. In addition to It's MI
crometer. the big telescope is equipped
with all other accessories. such as
spectroscopes. spectrographs. spectrorelio-
graphs. photoheiicgfAphs. etc.
While interest centefs around the main
dome and It's s.eepiess eye, the Yerkee OBJ
servatcry would be q big institution II Il
had only its minor glAsses to depend upon.
One OF these In . twelve-inch refractoe
mounted In the north dome. A twenty
four inch reflector viii shortly be mount
ed In the south dome. A sixty inch reflect.
ing telescope Is also being built now IN the
Instrument shop of the observatory. and
VIII be mounted in another building a,
some future time. As II stands euuiuued
the ftrkes observatory cost $5eno00 It Is
the most complete in the world. with a re-
frAeting telescope forty inches In diameter.
Next In orr is the Lick observatory. on
Mount Hamilton. with its ,hirty-six inch
tct anu illIFC IN Crucf fS the imperial
observatory at Pulkowa, Russia. with n
lens thirty inches in diameter
what Astronomers Are seeking
The sun. with all its attendant planets
comprising our solar system. is rushing
toward the star Vega. or Alpha, of the
Tyre. at the inconcelvahie rate OF ten miles
second. Vega IL one OF the most beau
uius stars In the heavens. and can be seen
now near the zenith on airy fair evening.
Probably since the life Of man began. Der.
hsps since the universe was born. our So
Iar system has been speeding toward this
star. In the life of generation the sun
comes hundreds. OF millions of miles nearer
its destination. But In many generations.
II all Appeara noes. this APPROACH would
nc; be perceptibie. The Journey. so far n
mnrtals arc concerned mist be eternal.
When. where. and how. II ever. aid
This Journey begin; when. where. and how.
IL ever, viii IL endT'
This Is The greatest OF the unso!yed prob
isnns OF astronomy. Night after night and
day after day the most powerful telescope
IN the world keers watch. IL Ia spvinx