The Wheeling daily register. [volume] (Wheeling, W. Va.) 1864-1878, 1876-02-26
AGIANT TELESCOPE.
A Description or the, Great Teles-
cope Recently Placed In Position
In Paris.

A Description or the, Great Teles-
cope Recently Placed In Position
In Paris.
CHICAGO, February 90.
To the editor of the Inter-Ocean.
There has recently been finished and
placed in position in Paris great teles-
cope, and brief description of the instru-
ment. as gathered from recent European
scientific journals, may b, OF interest to
your readers.
First, few words as to the history OF
the enterprise. In 1855 LIE Verrier, the
then leading astronomer in France, pur-
chased two very large discs OF glass, in
tending to have them fashioned into the
detectives of great telescope. The
work of investigating the process for
cutting these large g asses was given to
the late Leon Foucault, an eminent
nhysjcist connected with the French Ma.
tionsl Observatory. While prosecuting
these Investigations Foucsult discovered
a process for constructing telescopes from
silvered glass mirrors, instead OF using
the metallic speculs employed
by Herschel and Rose in making their
enormous instruments, and used by OPP
ticians generally for rejecting telescopes.
The larSes, ofthese silvered-glass mirrors,
made by Foucault himself, is at Mar
settles, under the charge of Nj. Stephan.
1t is 3l@ inches in diameter, and with 1t
can be seen all that Herschel or Rose
saw with their gigantic specula OF 81 and
651 inches diameter This demonstrated
the value of the new process, and Fou-
CAN'T became DESTROYS of constructing
the largest mirror possible. LIE 'err'er,
to further this end caused TO be cast at
the St. Gaban glass factory block OF
glass weighing 81, 543 pounds, which was
rough ground and turned over 10 fou-
cault. To construct the monster aspec-
ial grant was obtained in 1860 from the
government of 10000 francs. ny 1865
Foucault had prepared all the plans for
the instrument. and had begun the
work. when death snatched him from
his Ii bors and deprived France OF one
Of its most original genulses. Inns
event and the troubles soon after, IN Il
great measure stopped all work at and
about the Observatory tor several years,
and it was not until La Nerrler was
again made director of the Observatory,
in 1873. that it was resumed with vlgor.
To NJ. Eichens was given the construc-
ton of the telescope; 10
NJ. Adolphe Martin the polishing
Of the mirror and to NJ. Wolf
the general perintendence of the whole
WAS intrustcd. In 1875 the mirror was
completed. and in October Eichens sent
in the instrument complete, though 1t
was not finally ready for use till Jan. /,
1876. The tube of the telescope Is
twenty-three feet four inches long, and
consists of a central cylinder, to the ex-
tremities OF which are fastened two tubes
nine feet ten inches in length, consisting
of four rings of forged iron, bound to-
gether by twelve bars of iron. The
Whole Is lined with small sheets of steel,
and weighs 5, POI pounds. AT the lower
extremity is fixed the barrel which holds
the mirror, which is 40 Dol inches In dl-
smeter: ut the other end n circle, nova
bic on the open end of the telescope car
ries ut the center n plane mirror which
throws TO the side, where the eye-plece Is
placed, the cone of rays reflected upon II
bv the great mirror in the bottom of the
t1be. The method of construction is the
same as that invented by Newton, and
has the advantage of giving more per-
feet image than the Cassegraln system OF
MERGING the mirror in the center Tor the
eve-niece In the latter case the observer
is ALWAYS but a short distance from the
ground, while by Newton's plan a stair
way has to be built to enable the observer
to get 20 the eve piece. In the present
instance the stairway is built upon n
truck, and is pushed round the foot OF the
telescope upon railway. Thus the OBJ
server can, by standing either upon the
steps or upon the platform on the top,
get into the position best suited TOR OBJ
serving.
The weight of the mirror and Its bar
rel is I.764 pounds, and the eye-piece APP
psra,us weighs the same Such Is the
weight that the tube has to carry, and
vet to keep the mirrors centercu upon
zach other it must not bend more than
O3a of an inch, even in the most untsvor-
able position. So well is the tube con-
structed that this amount OF "crooked Is
not reached.
10 make this monster of service to
science. it is necessary to be able to direct
il To any point in the sky, and to give 1t
such motion that 1t can follow the path
of any particular orb.
This is accomplished by mounting the
telescope upon an axis of iron and steel,
whore direction is parallel to the AXIS oil
the celestial sphere. Then lit may be
/ inclined more or less upon tins AXIS by
/ turning IT round on a second axis of steel,
which crosses the other At right angles
ard psr;akes in its movement of rotation.
The whole arrangement OF the double
owls is a mechanical wonder, from the
case Of its motion. This mass, like the
/ hand of a great thermometer must follow
with preci,ion the march otthe stars IN the
vault of heaven, obedient to the actlon OF
clncLwork controlled by Foucanlt reg
nlstor MIR. Eichens has preserved the
delicscv of fine machinery, while giving
to each part sufficient strength to supper
the mass of the telescope. Friction is Al
mos, annihllated and the observer can
move the instrument in any direction oy
means of simple contrivances at his hand
The optical performances of the teIe'
| scope have so far proved admirsoie'
Notwithstanding the great weight of the
mirror, It's shape is SO perfect that the
rays o. star are gathered up into SIN
gle point, and the images OF the planet:
are perfectly true.
From what has been said above re,
gardiug the accomplishments OF the
Marseilles mirror of 81 ago inches diane.
ter We may expect great results from the
Paris mirror OF 1924 inches. The tcles
cope will be completely fitted up with
Photographic and spectroscopic appsra
tus. OF course the use Of such al enor.
nous instrument requires long appren.
,iceship, and the present astronomers
may practice long before performing any
special work. 1t is proposed to use ii