St. Tammany farmer. [volume] (Covington, La.) 1874-current, 1884-02-23
How Your Spectaclcs are Made.

''You want to know something about
spectacles and eye-giasses?" asked the
optician. in answer to the query of the
| Herald reporter. ..Well, here is the be.
ginning of about ten dozen of the finest
Accompanying these words a huge
lump of what seemed to be mass OF
dirty white glass was produced. 1t was
of an irregular shape, somewhat like a
cone, the sides of which We're of vel
low-whitish hue, while the base showed
clear. transparent body without the
slightest flaw. That part of the mass
showed that the lump was only part of
a larger body. because the surface was
plainly an artificial one
Don't be afraid to drop it, re-
marked the optician. '.it wouldn't break.
1t is Brazilian pebble. and one of the
finest and largest specimens, too. You
see the base has been cleaned and pol
ished, so that we see what we buy.
This lump sawed into slabs and cut into
the requisite pieces will make about two
hundred lenses for specs and eye
glasses
ITO what geological period does the
pebble belong?" gueried the reporter.
''Well, that is more than can say"
was the answer. This mineral un-
doubtedly owes its existence to some
volcanic eruption. 1t Is not very long
since that pebble tonk the place of glass
In spectacles, and the exact nature of it
has not been sufficiently defined to class
ify it properly. All we know Is that
pebble. in large majority of cases, is
f..~ hot fh,v rlo-, % I1E
cheney in the sight of human beings. The
manufacture of pebble lenses is one of
the great advances of industry aided by
scientific research"
1t certainly seemed so to the reporter
as he took second look at the dirty and
irregularly shaped lump of mineral on
the show case and then glanced ut the
pair of fine gold-rimmed eye, glasses
which his informant wore.
"A good deal of nice work and ingen-
ious machinery is require said the
latter, ''to make lenses out of such a
piece. The cutting is done by exceed
ingly fine rotary steel saws. which have
to be driven with an almost incredible
rapidity to prevent the splitting of the
pebble. The machinery employed is so
complicated and expensive that it
wouldn't pay for even my large estab-
lishment to cut lenses in the rough.
That part Of the work is done in Scot
land"
''Why in Scotland?" calculated the
reporter.
Because they have the only estab-
lishment Of any account for cutting peb-
bles in that country. You see, the first
pebbles were found in Scotland in the
mountains by miners who were pros
pecting for copper, but the supply gave
out shortly after the expensive works
We're started. They find pebbles yet in
Scotland, but Brazil yields large sup
ply, which is shipped to Scotland, where
it is cut. 1t is then reshipped to this
country. Even the bulk of the work in
finishing the rough lenses is done in
Europe, principally in Paris. That part.
though, could be done as well here if
we had the demand for it. However, it
doesn't pay except on large scale.
Whatever little fitting in particular eases
is necessary, every optician can do
'.How are the rough lenses finished?"
-''They are ground down to the
requisite dimensions by steel disks, and
then polished by means of sand, dia-
mond dust and substance called
rouche: that is. the lenses for ordinary
use. There are eases for defective |
sight where several layers of glass have
to be melted together and ground down
again and again to produce the exact |
focus for the particular ease. Lenses of |
that kind are very expensive. but then |
they are actually invaluable to the |
wearer, who positively could not do |
without them. That is what we call |
fine work, and there are but few opti- |
clans who can do that. Any peddler of |
an average intelligence can set YOU a
pair of spectacles which, upon the first
instance would suit your eve well: but it |
takes good knowledge of the eye and
its defects to fit You with pair of |
glasses that will really benefit YOU. and
what is more, do you no harm. There
is great deal of harm done by the in
iudicious wearing of glasses. Let me
say that many people throw large con-
sultation fees away to physicians who
are not even good occulists for having
suitable lenses prescribed, where prac-
,ical optician could save them the fee
md fit them better. Then, of course.
here are people who don't know what
hey want, or have no use for glasses,
ike the fellow in the old German story
Who could not be suited by any optician
With a pair of specs for reading. You
that the last optician he went
o discovered that the old man couldn't
cad at all"
''What is the advantage of pebble
'ver glass?'
..Pebble makes the finest lenses and,
What is of great moment. is cooler and {
asier on the eyes. The body is more
old, less liable to scratches, consider [
bly, stronger and whittier. that is. more
than glass. A few kinds of ]
crystal have been found i'm the :
'nited States, but they are not so fine {
uality as Brazilian and Scotch pebble. I
hey are so soft that they don't wear
ell, and are therefore practically use ,
,Ss." T
docs the quality of the rim make
ny difference in wearing glasses"
.'Only as far as the pocketbook is con-
,rned. Steele, tortoise, silver. or gold, /
: no rim at all are equally good for the r
res, provided the lenses are of the right b
lmber and the focus is correct. You f
e, the frame must be SO shaped that r