The Somerset herald. [volume] (Somerset, Pa.) 1870-1936, 1896-07-15
To The Moon, 38 Miles.

The huge block of crystal which Will
become the mirror for the great tele-
scope has safely arrived in Paris. If all
goes well the exhibition of 1900 will be
able TO boast Of a distinct feature.
| Whether the moons features will be
equally distinct is another question.
Professor LOewy thinks not, but NJ.
Deloncle is still determined to carry
through his idea
''The moon one yard off" II was
thus the scheme of the gigantic tele-
scope was spoken of in the papers, but
VI. DelOncle, however ambitious he
may be in Central Africa, protests that
he never had 80 prepOsterOus a notion.
He claims that it will be possible To
throw on to n screen views Of our satel-
lite brought within a distance of thirty
eight miles. This remains to be seen.
However, everybody will wish NJ. De-
Ioncle, and still more especially his
shareholders, every success in what
one must stiil regard as an experiment.
The new telescope mirror is th=
largest ever made. 1t was east at Jeu-
mont, a manufacturing place, and the
last French station on the line 10 Liese,
Cologne, and Berlin. This splendid
block of homogeneous crystal weighs
5000 kilogrames. Its dianeter is 2.05
meters and in its present nearly rough
state il cost e4,OO0. OF course il was
conveyed to Paris in a special train. It
was wrapped up in heavy felt blankets,
protected by hoops of soft wood, with
metal tires, mounted on pivOts. Thus
packed, the mirror was tightly wedged
in case that was placed in the wagon
on bed of hurdles and layers OF hay.
For greater safety, tae train stopped
only once, at Tergnier, and went at a.
slow pace As 4 royal train, escorted
by railway inspector. 1t was insured
to its full value. the same afternoon
it was removed from the northern ter
minus to the workshop. The mirror,
before leaving Jeumont, went through
second grinding of its faces, being as
smooth a. fine plate glass. But for
telescope purposes this sort of smooth
ness is rOughness itself. The finishing
processes will take two years and six
months, and by more expeditions pro-
eesses than any hitherto in use, which,
moreover, will give greater accuracy
than anything known.
Hitherto astronomical mirrors and
lenses have been polished by hand by
slowly rubbing the glass with the
naked hand, sometimes, but not al
ways, moistened with oil, albumen,
and other substances, which are the
m lker's secret. The drawback of this
process is that the mere heat of the
h md may cause the surface to warp.
The new mechanical process, of
which particulars are not given, will
produce a surface approaching true
plane, within the one-thOusandth part
of a millimeter. Even this marvellous
finish will leave a margin, astronc-
mers say, for errors. The whole finish
ing process will cost 5000. The sill
vering will not cost anything to speak
o..
The mirror will be mounted on two
arms ten meters long, and will be set
in motion by machinery Of the usual
sort. The rays gathered from planet
ary space will be reflected horizontally
through a mammoth tube sixty meters
long, laid on piles of masonry. The
lenses of flint aud crown glass will be
one meter twenty-five centimeters, the
| largest in the world, and the images,
enlarged 5000 times, will be thrown
on to screen which thousands Of
people will view at time.
The moon will, if all goes well, be
brought within thirty-ei ght miles, but
it is most doubtful whether images on
this scale will prove correct. NJ. LOewy,
the Assistant Director OF the Paris o.
servatOry, who has submitted some
splendid photographs of the moon,
believes that the limit Of ninety-fOur
miles he has reached Is the utmost
practicable for long time - come.
Larger images will be indisiinct.