New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1873-11-17
TILE GREAT WASHINGTON TELESCOPE

AN INSTRUMENT OF EXTRAORDINARY POWER
INGENIOUS CoNTaYANCEs WHICH fACIiIfAfH
IT'S USE.
(yRoM AN OCCASIONAL CORRESPONDENT OF flE THBoNEI
WASHINGTON, Nov. Sit is not to be won
dered that stranger. making his first pilgrimage to
the political metropolis of the country should hnd MN
self gazing with admiration and pride on the vast proper
tions of tho dome of the Capitol BE bestows his ad-
mraton as thousands have done before hin on great
and lasting monument OF architectural skill
In distant part Of city, scarcely TO be noticed by
the stranger and almost unknown 10 many Washing
tonian are the twin domes OF the nations Astronomical
Observatory No stupendous piles OF architecture meet
tn, eve OF the visitor here but hid In modest secuson
beneath the larger dome the monster telescope For
thirty years the Observatory has cOntented itself with
the use Of an equatorial instrument OF puny
such as many amateur possesses Congress- WIN us
accustomed muncenoe IN its contributions to SCIENCE
some years since appropriated $4,000 for the consrde-
ton of telescope which should be true representative
Of the present high state OF advancement III the manu-
facture OF such instruments, and powerful agent IN
astronomical research The construction, which was u-
dertaken years since, has been successfully coin-
pleted and the telescope IL being mounted at the
Observatory In Washington, and Will soon DC aea'.y
employed in the nightly vgils OF the astronomer
Our own countTymen. the Clarks OF Cambridge, Mass
who constructed the instrument carry the aures or
being the most successful optical artists IN the world
From the smallest beginnings In telescope making they
have made steady progress, I'LL they have reached ms
nresent stage of excellence. This instrument rs OF
American manufac ture. The only foreign element in
its construction is the optical glass IA the ienEcs
Optical glass is only to be obtained by Importation
from abroad The dferent parts Of the. instruments
arc 40 finely proportioned that its immensely 10 lost
seht Of and the visitor On first acquaintance might
NOT give full credit 10 its vast olmehss0hs' Inc
protecting building Is circular in form, and apoai
40 feet IN diameter, and Is surmounted ~ dome o. e
same diameter, resting on circular system oi "heeS
40 that it may readily reyolyed through the whole
part OF a circle The dome Is provided ~lth s-N 81
feet In width from the horizon TO ite peyoh" ''s
zenith; this is protected by sliding shutter
Tina telescope Is equatorialy mounted, thai II, has
two axes of motion light angles to each ole one OK
which is parallel to the esrth's axis consequently 'Do
telescope may be made TO follow tho diurn roNeleBt
OF q heavenly body by reyo.iag- ~ on
tlis latter axis alone which Is eoHmopY
called the polar axis because is directed toward me
poe OF the heavens The instrument rests on pies of
stone and brick work whose foundations lS feet be-
low the surface. The pier is capped b. sinse ooe ~
sandstone weighing about two tons On THIS stone res
heavy casting some seven feet IN hight and @ei2h
ing one and quarter tons. which supports the sntEe
instrument The weight OF the moving parts - abosi
four tons The facility with which this iolGense mass
can be moved certainly surprising. The gentle pres
sure of the hand is altogether sufficient. The
about which the parts OF the instrument 5 about
II feet above the floor Tie telescope time is Of sheer
steel riyeted together like the funnel OF steamboat
II is somewhat cgar.shaped The length OF the instru
ment is Slt feet When 1t il pointed directly overhead
the object glass is elevated IS feet above the floor
However wonderful the parts of the mounting may he,
the greatest interest Will always center in TIC eant eye
OF the monster When it s said that this nessuFesi 10
available diameter 20 inches 1t conveys 10 .w an abe
aate conception OF tie patience aud st OF ths glass
founder and repeated failures before be produced
disks without flaw or of the vsst experf,1en AMI er9
se,foyed on the disks by the opGean H. bnucus Them
to an absolutely perfect lsnre
The standard OF pufly and uniformity ~ Ger afy IN
op tiesI glass is SO very hiyh that the manufacture e
limited IN urcpe 10 very few establishments Mesrs
Chance & Co. OF Birmingham, England, furnish th,
Csrks with most o. their optical glass. Tho dn"glty ~
brleating LARGE dicks " optical glass increases very
rapidly with their size; consequently large SKIS
maud very high price Thus while the disks Cor the
lens Of the Is.nch glass Of the Dearborn Observatory
Chicago cost s2Ooc tor,thc esinch glass Wash
ington cost The object glass Of every rchromaiis
telescope consists OF two lenses OF rnt and tbe
otaor or crown glass; the beam OF light transmitted
through them produces cooress image at the locus
The instruments 70 FURNISHED with iiaely isdst.d He
visions under tho reading microscope are iiiunipasd p
passing powerful urrentof electricity lbrodsa asnsn
NE two merosco,s for reading The declination erco
s.e 80 situated That they may De resa " 'n' "O'ef'e'
The pier of the Instrument contains an srchway, IN
Which mounted the cock.work which moves me tee-
s.ope 80 that an object may held Ia the noid OF view
As long as may be desired. The motive power Is roac
tiei wheel driven aQueduct water az the rate OF
thres turns an "a scond Tho regulating apparatus 10
cancal penduiup once IN two seconds. which
4. Nv controlled by an electro agDet which
orts frison ON revolving DIRK when the velocity IL
Too great and removes if whcnH Is too small.
the question Is often asked, How much does this
,oe magnify how much more does one felescopo
,esgrfily than anothert Such questions never he
OF S arc Assd ossso.s
axod onantiy: Inc magnilytng power depends on the
eyepeee. Telescopes Of any considerable siro are AZ
ways furnished with variety of sye-peces. The sizo
d.terinne power. large object glass afords srssS
amoupt Of light, and renders the eecs OF atmospSere
dsfWpances less troublesome 70 the observer, and
merely enables him 10 examine obiects with
rosrer facility with the same maxnifying power. u
There plenty Of work 10 be done WITH th powerful
implement VI discoyery. The astronomer be 90 need
20 he'd ears as did Alexander the Great because there