The Roanoke times. [volume] (Roanoke, Va.) 1890-1895, 1891-07-26
THE LARGEST LENS.
A Telescope with q Forty-Inc
Glass for Mt. Wilson.
Ie WAL DO Constructed for tho University
OF Southern California and Will DO
Located Near tho City OF
Los Angeles


The ambition Of tho astronomer to
probe deeper and deeper Into the
fathomlcss depths Of space and to bring
order Ito his sight, for his mind tells
him that order exists) out OF the up
parent confusion has kept the glass
makers and opticians busy, with tho re-
suit that the flve-inch single lenses of
Huyghens, that required local length
of forty, fifty or ono hundred feet, were
improved upon by the invention of the
achromatic lens by Dolland, upon
which subsequent improvement has
been made only in quality and power
and not in principle.
The four-inch lens of Dolland, fn 1900,
developed into the nine-inch lens in
1880, and from 1916 to 1861 the fifteen
inch telescopes at Harvard OBSERVE
tory and at ST. Petersburg were tho
largest and most powerful instruments
in the world From that period till to-
day the size and power have constantly
increased, first to eighteen inches, then
to twenty-thrce, twenty-six, thirty,
thirty-six, and now the Clarks, of Cam
bridge, will soon be working upon one
forty inches In diameter.
At various stages of the progress of
telescope making, says the New York
Journal, 1t was thought that the limit
of useful power had been reached, but
after each increase 1t was found that
with proper selection of site the
density of the atmosphere did not Inter-
fere so much with the observers as was
anticipated.
About the forty-inch glass which Il
for the university of Southern Cali
fornia, and which arrived here short
time since. Mr.. Clark says the managers
have not yet given him contract to
make the lens for it, but he expects it
every day. He has the glass, and no
other optician in the world can do the
work; so there is no doubt that he will
do It
Mr.. Clark has offered to make the
telescope complete for s1OQ 900; that Is,
visual telescope, and he has further
agreed to make 1t both visual and pho
tographic for S10a,ooo, An interesting
incident is connected with the inn
portation Of the glass When Charles
Sumner was In the national senate he
introduced bill designed especially
to allow Alvan Clark. ST., to import the
glass for his lenses free, and the law
still remains But recently the treasury
department. made a decision whereby
disks for lenses are subjected to duty
of As per cent.
This meant everything to the Clarks,
as they would have had to pay thou
sands of dollars tax on glass they had
already ordered, tho forty-inch glass be-
ing included Mr.. Clark went to Wash
ington, and, backed by several distin-
guished scientists, endeavored to con-
vince tho department that under the
law the glass should como in free, but
First Assistant Secretary of the Treas.
ury Tichenor, who made the decision,
refused to be convinced.
Mr.. Clark returned home with thor
ough determination to take his tools to
Europe and to do his work there, but
Senator Hoar interested himself in the
case and the decision was reversed
Mr.. Clark says that he Will In all prob
ability not begin ON the lenses for q
| year, and as 1t viii take two years tc
| do the work on both Of them-the fin,
! glass has not yet arrived-it will be
three years before the telescope is fin.
ished.
When completed It will be mounted
in ON observatory to be situated or
Wilson Peak. thirteen miles from Los
Angeles, Cal Mr.. Clark and Prof
Pickering, Of Harvard. think that this
is the finest site for telescope in the
world. The atmosphere Is clear ono
steady-conditinns necessary for gooc
observations.
It should be mentioned In this con
nection. perhaps, that Mr.. Alvan G.
Clark Is practical astronomer and Is
the discoverer Of many stars-among
others the Clark star within the trape.
zium of Orion-with the Lick telescope
The magnifying powers of the Lick
lenses can bring the moon to within
about 100 miles of the earth, and the
4o-inch lenses will bring it to within g
much smaller distance MIR. Clark has
insisted that he shall have the mount,
ing of the new telescope, so that the
laundering that took place In the in.
stance of the Lick telescope, and which
necessitated his finally being called
upon, shall not be repeated.
An Assumed Name.
There is o quaint old man in Man
ohoStar Enn who cr,~oo wv f1o