The Superior times. [volume] (Superior, Wis.) 1870-1912, 1885-05-23
THE LICK TELESCOPE.
Some oil the Fine Work Involved in tn,
Construction of the California Instru
ment.

Some OF the Fine Work Involved in tb.
Construction of the California Instru-
ment.
In 1850 q contract was made with
MeSsrs Avian Clark q Sons to furnish
an objective of thirty-six inches clear
aperture This was siA inches greater
than the glass they had just arranged to
make .or the Rus ,ian Government. and
thus he telescope would fulhll the con
d.tion of being the largest and most
powerful ever made. The result has
proved the old rule, that the LARGER the
glass the more difficult it is to make il.
In this connection there is a eur. Gus
contrast between our present experience
and that OF the OPTICIANS in the early
part OF the century. At that time the
making OF the crOwn-Giass Tor the
double lens offered cOmparativcl, little
difficulty; it was the lint glass with
which the trouble was found The lat
ter contained lead, a substance of great
SPECIFIC gravity, which persisted in set
ting toward the bottom Of the rot in
which the glass was melted. and Thus
producing difference between the two
sides OF the glass which was fatal TO its
performance. But this officially has
been SO completely overcome that all
the trouble now arises with tie crown
glass. The method OF making the best
tint was long supposed TO be a secret IN
the hands OF . Swiss named GuiuanI and
his family; but it is now e.ieYcd that the
supposed secret involved nothing more
than the very simple device Of continu-
ousiY an vigorously t.rrIng the molten
glass mt it Negame too cold and stiff
10 permit til heavier mater al 10 settle
However this might be, Fell, Of Paris,
who has been most successful in max
inc large discs, supplied a satisfactory
flint in a reasonable time. But SO much
delay was met with in casting the
crCwn-g!ass that it has not Vet rea, II a
the hands Of the Optician. The caaSa
CT his failure is one 50 simple hat one
can not but wonder that it should ole.
any trouble after being tnce detected
We cal. to mind that when the founder
has succcc led in casting his lump Of
glass, weighing several hundred pounds.
the clay pot in which it is contained IS
broken away. The outside portions OF
the glass itself, being unprecedented with
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