BRINGING DOWN STARS,
Something About the Construction of
Big Telescopes by Alvan Clark,
the Clever Yankee
He Meakes Lenses That No One
Else in the World Can
Infinite Care and Patience Required in the
Work-.Some Very Wine Calcula.
tions Are Required.
tWratten for Tea HELENA INDEPErNDENT.]
IIHERE IB NOTHING MADE BY
human hands that is more nearly
perfect than the object glass of a
great telescope. Each slender thread of a
spider's web is composed of many thousand
strands, each strand so fine that four mil
lions of them would make a thread no
thicker than a human hair. In other words,
roughly speaking, a spider's strand is as
much smaller than a hair as a hair is
smaller than a telegraph pole. Yet in the
lens of a great visual telescope a deviaton
of the breadth of a spider's strand would
be noticeable, and in a photographic
telescope it would be fatal to the pur
pose of the glass. Americans, accustomed
to hearing their countrymen accused of
slipshod methods in the manufacture of
their wares, cannot but take pride, then, in
the fact that the man who makes the great.
eat refracting telescopes the world has ever
known is an American of the ninth genera
tiop. Mr. Alvan G. Clark, of Cambridge
port, Mass., is a descendant along the male
line of Thomas Clark, the mate of the
Mr. Clark's father, the founder of the
famous house of Al-an Clark & Sons, tele
scope makers, was a very remarkable man.
Until after his fortieth year hedevotod him.
self to portrait painting, and so accurate
was his eve, so delicately skillful his hand
and so inexhaustible his patience that his
portraits stand to-day almost unexcelled in
point of likeness and well nigh unsurpass
able in point of exquisitely careful finish.
In everything that required keen vision and
close exactitude he was successful. It is re
lated that once he watched a game of bil
liards, saying at the close that he believed he
could play, and although he had never before
handled a cue he played a game far above the
average of ordinary billiardiste. But perhaps
the most wonderful of his many accom
plishments was his markmanehip. It is
ALVAN O. CLARK, nR.
said that with a rifle he could put bullet
after bullet thlough a distant board with
such precision that one would say only a
single shot had been fired, and this is par
tially ex.lnained br the fact that he made
his own rifles with his own hands, and used
that same marvellous exactitude in the bor
ing of the barrel, the setting of the sights
and the cutting of the bullets that after
ward gave him his world-wide fame as a
It was not until 1843, when Alvan Clark
was more than forty years old, that his at
tention was turned toward telescorpe mak
ing. In that year the accidental breaking
of a dinner bell at the 1'hillips Academy,
Andover, prepared the way for the most
important advance that the science of prac
tical astronomy has ever made. George
Bassett Clark, son of Alvan and brother of
the present Alvan G., was a pupil at the
noacdemy. Gathering up the casta~way frag
ments of the bell he took them home, rut
them into a crucible with some tin, and pro
ceeded to melt them in the kitchen fi e, in
forming his mother that he was going to
make a telescope. ' he mother smiled in
dulgently upnoon this potteriung interference
with her more important culinary arrange
ments, but the father, when he heard of it,
took a more slriour view of the mutter.
Me became no deeply interested in the
work that he laid aside his 'paints and
brushes and gave his time and gen
ins to the shaping and polishingof his son's
reflector. The result was a five-inch re
fleetung telescope which show'ed the satel
lites of Jupiter, the rings of Saturn and
other telescopio objects. That was the be
ginning from which have grown, in gradual
succession, the famous refracting telescopes
of the Vienna university (12 inch aperture),
the Morrison observatory (12.; inch), thie
Wisconsin university (153 inch), the War
ren observatory (1l inch), thi Northlwestern
university (18t2 inch), the Denver univers
ity (1) inch), the P'rinceton university (23
inch), the University or Virginia (21t iach),
the United States NavaIl observatory at
Wabshington (26 inch), the Pulkown ob
seIrvatory of lunsia (30 inch), and tie great
Liok observatory of California (30 inch),
thie largest lens in the world, though a still
larger one is in prooess of constructiou, as
1 shall show later on.
Alvan Clark never again took uphispaint
brushes nlitil forty years later, when, at the
ace of 83. he made an exquisitely beautiful
and wondrously lifelike portrait of his
grandson, who had recently died. This
young man, the only son of Alvan 0.. was
the hope of the family, if not, indeed, the
hbPe of eastronomical science, for it was to
him that the great work was to fall when
his grandfathur and his father should have
passed away, and he was being carefully
trained, ne his father before him had beaen
from early boyhood, to the methods which
hrd made thbis house pre-eminent aulong
the world's great lens makers. It is a raut
ter of serious import that the only mean now
living who can marke these great lenses is
well ulong in his sixtieth year.
The street car conductor told me I should I
know Mr. Clark's place when I came to it,
for it was "a big yard fullof smokestacks."
Tlhe "'smokestacks," I found, were tele
scol a tubes, for whenever Mr. Clark makes
a glass of new size he erects a rough tube in
which to test it on the stars, and these
tubes all remain, monumental reminders I
of his successive triumphs, for in 1862 he 1
broke the record of large lenllses, anid ever
since has been breaking over and over his
ownr otherwise unapproachable record.
Little attention is paid to the general ap- 1
nearance of this big yard. In front stand
two neat frame houses, one the old home
stead where Alvin Clark lived for more than r
half a century, the other the more modern
home of Alvin G. DI)own at the rear of the
gently sloping pgrounds stands a small, I
shambliung brick structure, pioturesque
enough, but hardly suggestive of the uniquae
enterprise it shelters. In thislow building, a
buried to its window aills, Mr. Clark, with
only two asristantsll. shapso and Irinds and a
polishes the lenses which nmake the heavens
yield to us their thrilling mysteries.
I cannot hope to give in a few words any
thing like an adequ ate idea of the skill and
patience employed in the mnnufnotoro of s
these aret objectives. The story umerelyof r
how the glasrs, the raw matertial, is made a
would warrant the use of more thtran I have c
at my diposal, liut a slggeetion of the
aioetj of this latter proceu may he found1
0111 Ue l l:enaI :lem es lre 1! ! l ig arril U UUL Ii I
And to get an idea of the progress this town has made during the dull times let us review the situation.
The old steam motorlinehas been converted into the Rapid Transit. The cracker factory is in course of construction.
The army post has become assured. The artesian well is being sunk under promising oiroiumstaL.I
The auditorium built. The Castle railroad will soon be built.
Paving Main street has begun. The Missouri dam scheme is in excellent shape.
The Whitlatch Union mine is in full operation.
Helena Real Estate Will Never be as Low Again as Noe
Most excellent opportunities for building sites, of moderate cost, are offered in the
Brooke, Syndicate, Ames and Bellevue additions.
This is one of the best neighborhoods in town, and for the benefit of those who are not
acquainted we mention the names of some of the residents:
James Porter, A. J. Craven, Judge Eddy, S. K. Davis,
* W nm. Muth, C. P. Connolly, Hon. O. T. Crane, E. F. Child,
", * * * R. H. Floyd-Jones, W. F. Franklin, Capt. S. A. Swiggett, Homer Hewins, *. .*. ,
Dr. Foote, E. Sharpe, Robert Smith, Jerry Collins,
John C. Paulsen, Geo. B. Child, Mrs. C. Goodell, and others.
Dr. Lawyer, Thos. Bach, E. H. Train,
Judge Hunt, Judge Adkinson, Emmett Fisk,
J. H. Lawrence, Maj. Baird, E. S. Clark,
This location has water direct from the mountains, two street railways which give excellent service, a beautiful sohool
building, is in direct line with the Broadwater, and will probably be in line with the military post.
We are now offering special inducements both in land and building. Now is your opportunity.
GC S. ATPPLE TON,
NOS. 3, 4, 5, HOLTER BLOCK, HELENA, MONT.
in the fact that almost four years ago the
lassemakers began work on two disks from
which Mr. Clark is to make a 40-inch lens
for the ipence observatory a t Los Angeles,
Cal., and only one of them has as yet been
sent to Mr. Clnrk. Time and again, with in
finite care and patience, the laesemakor
must try. for if there be a speck, a bub
ble, a wave or a flaw of any kind, no mat
ter how minute. Mr. Clark will not accept
it. ''o show me how clear this glass must
be Mr. Clark placed in my hand a six inch
disk, covered with an opaque substance.
and asked me to look through a hole which
ALVAN G(. CLARK.
seemed to have been out through its diam
eter. I said I sanw nothing strange; it was
like looking through any hole.
"Exactly," said he. "only you are not
looking through a hole."
I weas louking through six inbches of solid
lasas. What seemed tobe a hlewas really
two diametrically opposed pinces where the
opnque coating had been removed. I hen I
was informed that if a wall of such glass
ten foot thick stood before mrue in suchn
position that I could see no leflectiou from
it I should not know of its presence. It ie
literally as clear as air. No wonder a sin
gle diet of it forty inches in deameter anil
perhaps ten inches thick coats Mr. Clark
'1 he process of making a lens from such
a disk is exceeding ly simple. 'here is very
little machinery nod no secret. If you havo
the necessary patience, Mr. Clark will let
you stand by and soo all the work done.
First he tests the disk for sthies-that is,
he sets it up on edge midway orf a long,
dark room. At one end of the room he
plncus a light, then takes his position at the
other end of she room. An asslitant now
holds a lenas between the light and the disk,
and as the rays are intensified upon the
disk they magnify whatever streaks or
waves or inequalities of whatsoever nature
thlere may be in the disk; end Mr. Clark's
keen and practiced eye can determine
whether the flaw is in the body of the glass
or near enoughl to the surface to be removed
by the polishing proocss.
Next he tests it for polarized light by
simply taking itto the outer light, laying it
flat upon a polished redwood bed and view
ing it at a proper angle through a revolving
Nicol prism. If, as the prism turns, the
disk changes shades regularly and evenly
throughout its face, it is good optical glRas,
but if it shows cloudy in spots or streakl it
must be rejected.
Having stood these tests. the disk is
ready to be shaped. But first a very im
portant problem in manmaheatios must be
solved. An order for it telescope cOntains
two essential speoi8fcations-u-nmly, tihe
diameter of the object glass and the length
of oons. If. for example, the order be for
a fol. -inch aperture nuda fifty-fuot focus,
Mr. Clark must determine what curve to
ive the Rlale in order that every ray of
light which strikes its surtfae may be re
frected to a common point pro
cisely fifty feet away. When this in com
pated, an iron casting is made of the airs
nd slhape each side of the lons is to be-- a
concave Castlling for the convex side of the
glass and vice veren. This casting is trned
up on a latlhe and the disk is laid upon It
uand revolved, steel crushinRgs being strewn
between the two to rind the disk. This
brings the glass roughly into the shape of
the lens. Then, with eight courses of
emery, each course finer than the preced
ing one, the disk is ground with an adjust
able tool or form so constructed that the
pressure may be increased or diminished
at any point. Thus the disk is brought
into approximately its final form.
This is all comparatively coarse work.
It is really very fine work. In
making the measurements at this stage Mr.
Clark employs an instrument (a homemade
affair, which looks as if it had been whit
tled out with a jackknife) that registers
one thirty-thousandth of an inch. "But,"
says he, "this is used only for coarse meas
urements," No instrument can be made
by human hands for measuring the infini
tesimal distances which are so important in
the final shaping of one of these great
lenses. The human eye, and a rarely keen
and long-practised one at that, is the only
instrument fit to make these measurements.
The final shaping and polishing are done
with beeswax and rouge. Think of crind
ing this flinty glass with beeswax! It takes
from eighteen months to two years to do it.
Oh, the patience of it! And then the final
testing:-Thu lens in taken back into the
long, dark room, whence it was brought
two years before. Again it is set on edge
midway of the rayless tunnel. An arti
ficial star-a point of light-is placed at the
lower en.l of the room and at the upper end,
precisely fifty feet from the loue, exactly
where the focus must be, an eyepiece is
fixed. Now the myriad rays of light from
the star must fall upon every point of sur
face of the forty-inch lens, and each must
full at such an angle that they all will be
refracted to a common point just exactly
fifty feet away. You cannot even imagine
a mathematical point-a- point so small
that it could not possibly be smaller. Yet
Mr. Clark's business is to make that great
forty-inch lens so periect in its curve
that every one of those countless rays
shall come to a ma:thomatical point at
precisely lifty feet. If one single ray
falls the breadth of a spider strand
away from that point, the lens. is defec
tive anti the lensmaker, with keen, blue eye
and his lifelong experience and his tiroless
patience, munst find where that particular
ray strikes the surface of the lens, and then,
with his lnImir of solt beeswax, or perhaps
with his thumb, he must lightly rub that
spot until this ray is turned into its proper
course: and this must be done so deftly, so
exquisitely, that meantime no other ray is
disturbed. It mnakes one's head swim to
think of tile finonees of this work.
"And with your bare thumb you can wear
down such glass as this?" I asked.
For answer Mr. (Clark took up an old
castaway disk and gave it less than a dozen
sharp rubs with the smooth, soft thick of
his thumb. "There," said ihe, "if this had
been a perfeot lens that would have
changed its shape enough to ruin it." 1
wanted to raccuse the nani of playing upon
Iie, but his earnestness forbade. And thou
there was that mathematical point staritg
nse in the imagination. And as I stood
wondering whether I ought to be umnusad or
nmazed, Mr, Clark, pointing at the twenty
four inch compound lens he is snaking on
the order of Miss C. W. Bruce, of New
York, for the photographic telescope to be
given by her to Ilarvard university, said:
"When that lens is fiunshed we can hide
Tisi POttilt INsa ROOM.
,very ray of light frontm minany more tihan a
dozen stars at a time behind a spider's
stranud at its focal point."
'This ought to take the conceit out of
these foreign worldsL I freely admit it
took some out of sue,
WILLIs B. HAwsm.s.
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Recently the followlnq Notice appeared In the
San Francisco Chronicle.
"' lodge S- haed teertn ick only abotut two
wrels, eau it was lot unteil the te't three or
four days that the itaindy tosek a serious turn.
At tIhe beginning of his illnetss te suffered finom
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kidneys refused to pcrform their functlions and
he passed quietly away. Thus ended the life
of one of the most prominent en in Calnti
fornia." like thlousandis of others his nn
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are troubled with cdiabetes, gravel, or aon de
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loroe of refin led (te white lronree andl its
peelli.ealdaptabilitv makes it exmcellent for the
A Few More Local Agents Wanted.
E. S. HALL,
Gen. Agent for Montana and Idaho
3 ba·rapoefhe tsainedy for the .boe dlieae by It
-= thousande of uaeee of the want kind and of long
asnd.iog hve vbeen ourd. Indeed so strong is my taitr
Iattcmoar, that I will setn TWO OTT.IrrS r.a.with
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o. A. Slhum 1. Mo. . 11 P.earw a.. s
WE ARE RUSTLERS
41- FOR TRADE. *y Y
At the head of the procession, with the right swing,
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The "Frisky Dollar," in all lines of
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There is no Dealer in Montana that can
"ROUND UP BARGAINS'
To equal yours respectfully. We are here for business
from the ground up. and propose to let the world know
it. Come and see us.
THE NEW ENGLAND SHOE STORE
BRTTNELL'S OLD ST
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