Morris tribune., 1885-08-05
STONE TO PEEK THRO'.
An Opticians Views on Spectacles-Good
Glass Given tho Preference.

uEtSS SbNCu tHo ATChcrVhSVs
There is good story told on down
town optician. He sold n pair of gold
trimmed spcctacles, protesting that the
sights were pebbles and not glass The
purchaser later on had the alleged peb-
bles taken out by another optician and
fitted into eyeglasses. The latter were
taken to the first optician, who was
asked whether the sights were pebbles
or glass. He recognized Immediately
the mark of his competitor on the
frame, and unhesitatingly pronounced
to be glass what he had sold as peb-
bles, adding that the only genuine artl-
Gle could always be found ut his shop.
People who wear spectacles or eye
glasses, either from necessity or foolish
ness-and there is no small number OF
the latter sort-are as rule predls-
posed in favor of pebbles. They have
been told that pebbles are clearer than
glass, that they are more cooling to the
eyes, and that they are more durable.
As a matter of fact, the only advantage
pebbles have-to the dealer-is that they
cost more money; there is consequently
more money in handling them. mas
much as there is quite number OF peo-
| pie who believe that q newfangled artl-
Gle with a high price attached is better
than an old-fashioned one at reasonable
rates, pebbles will have their run, espe-
cially with that class of people who
wear glasses because they think it will
make foolish features look wise.
| To gain some information upon the
subject of pebbles and glasses the Her
aid reporter sought out a Randolph
street firm of opticians whose members,
though young, have an excellent repu-
tation in their line.
Judge for yourself" replied the gen
| tleman who was interviewed in regard
to the difference between pebbles and
glasses, with special reference to the
marks by which these differences can
be detected even by the uninitiated. A
fine steel file was produced, and upon
its furrowed surface a glass sight and
pebble sight were rubbed alongside of
each other. The mark made by the
glass was line of fine, grayish-white
| dust, while the mark made by the peb-
bic had simply polished the metal with
out leaving any deposit. -, -,
That is the simplest method, said
tho optician; lone that anybody can
apply. The pebble, being a stone, is
harder than glass. which is compound.
A more scientific test-for under GER
tain conditions glass as hard as pebble
can be produced-is what we call re-re-
Election. A tester containing two
priSms, between which the glass to be
tested is placed, will be non-transpar-
ent, while, when pebble is placed be-
tween the prisms, the latter will permit
a semi-transparency. This, however, is
but an optical delllsion, for the light
does not penetrate through both prisms
and the pebble, but through the sides OF
the latter and through the prism next
to the eve. This demonstrates that in
spectacles and eyeglasses with pebbles
as sights the rays of light which should
pass through the optical lens alone are
also reflected by the grain formation OF
the pebble, thus producing re-ret1ection,
which is hurtful to the eyes. In some
eases re-retiection is necessary so tina,
the artificial light is nearly as possible
the same as the natural, but these cases
are exceedingly rare. TO be palmer to
the popular understanding: If the lenses
of an opera-glass would be pebbles in
stead of glass the objects seen would be
| 10 tlle OIulHdlS eye SiothSN ~ "iA ."N
colors of the rainbow" No profes'
sional oculist prescribes pebbles" .
But are they not cooler to the eyes?''
Again, Judge for yourself. A peb'
BILE and a glass were placed side by side
upon piece of velvet which was or
the showcase. After remaining there
for few minutes test was made with
the point of the tongue. The pebble
was decidedly cool while the glass hae
assumed the temperature of the article
from which it had been taken. The
scribe was about to triumph, when h'
was asked to take a pebble in one ant
glass in the other hand. In less thai
no time the pebble had the same tenn
perature as the hand.
THAT would be the result if pebbles
were worn in front of the eyes, re-
marked the optician. ''Pebble Is a
stone, has the grain formation. and acts
on the eye like prismatic glasses. 1t is
never used for nautical instruments,
opera glasses or microscopes, because
of this fact. The best production of or
aid to the eye is glass, carefully adj
| iusted to the focus. But pebble is fash.
ionable, and if you want to buy it,
will readily sell it. '-Chicago Herald.