The Chickasha daily express. (Chickasha, Indian Territory [Okla.]) 1899-current, 1904-12-12

Ter has made some of the most delicate
lenses in use at the Naval Observa-
tory, the Astrophysical Observatory OF
the Sm.thtonian Institution, and other
scientific establishments throughout
the country, while 4 number of fine mi
croscopes, together with a large pro-
portion of theodolites employed by sur
veyors, owe their excellence to the
lenses which he has turned out in his
simple little workship.
A person does not necessarily have
to be yersed IN scientific matters to re-
alize that the accuracy OF the images
transmitted by such instruments as
the telescope, camera. microscope etc.
depends entirely upon the perfection OF
the glass surface upon which the inn
age is received and through which 1t
is conveyed to the human eye or the
sensitive plate. We are all acquainted
with the wavy looking glass, which
may be purchased for a few cents, and
which represents the human face d.
vine" most fearfully and wonderfully
distorted Between such n glass as
this and one that would faithfully re-
fleet an object with nearly absolute
exactness, there Is, as far as regards
mere cost, a difference Of several hun
dred dollars.
But the value TO the scientist cannot
be over estimated OF an exact plane or
curved surface OF glass The former.
especially, principally required in mir
rors for receiving the suns image. is.
as Mr.. Kahler will explain, one OF the
incest achievements in the making Of
optical instruments. In Illustration OF
this fact, Mr.. Kahler pointed to a disk
OF glass, sixteen inches ia diameter,
which vas conspicuous upon a dusty
work bench. This was to be made in
to a mirror for one OF the instruments
OF the astrophysieal observatory Of the
Smithtonlan Institution, and the work
which was TO be done upon ii, and
which would occupy some six weeks
OF persistent labor Of the most skilful
and laborious description, was to put
a perfectly smooth or plane surface
upon it. When this was accomplished
the unpretentious piece OF glass would
be worth $1,000 This may appear
strange 70 a person accustomed tc re-
gard the French plate looking glass in
his room as having a perfectly plane
surfacs and rejecting his image with
absolute exactness. To all practical
intents and purposes, indeed, the latter
object is accomplished; nevertheless,
the surface OF the glass Is a long way
from being a plane In the scientific
meaning OF the word, and in the re-
quirements of optical instruments.
In order TO realize the value of these
accurate mirrors, one has only to ex-
anime the method employed for taking
a photograph OF the sun each day at
the Naval Observatory. The image
OF the luminary is first received upon
a mirror and thence transmitted 10 the
mouth Of the camera. These sun pho
tographs disclose, with the most ex-
Qulsite mlnuteness, the structural fea-
lures OF the suns envelope" as the
luminous mass surrounding it has
been termed. The so-cailed sun spots,
for the observation Of which these pho
tographs are principally taken, are
shown in wonderful detail, the pecu-
liar fbrous structure attributed to jets
OF fame and the different densities
being clearly distinguishable. 1t is
scarcely necessary to observe that II
the mirror transmitting the image in
the first place were not a perfect
plane, or something very near it, the
picture. depending for its value upon
such minute detail, would be distorted,
confused, and absolutely worthless for
scientific purposes.
How do you test the surface OF the
glass in order to ascertain whether or
not it is a perfect plane." Mr.. Kahler
was asked.
For answer, the worker in optics took
two pieces of plate glass. "These
use merely to Illustrate" he explained. l
"Of course, these are by no means |
plane surfaces, though they are about
as much so rs will be found in the or
binary fire mirrors Of commerce.
use a plain surface for the purpose Of
actual testing, which place over the /
surface l am working on just as ]
place this piece Of glass over the
other Then l take a piece OF metal
screen aud dip it in salt mixed with
some inhammable liquid. and SO get the
yellow sodium rays. Now, after plac-
ing this simple apparatus in the tri-
pod here, | hold the two pieces OF
glass so as to catch the sodium rays,
and you viii notice the innumerable
lines. black and white alternately, that
traverse the surfaces Of the glass in
all directions. These lines, in accu-
rate planes, would be about half an
inch apart and would be parallel,
whereas. here you see them running in
curves. ziczags, and every other way,
and very close together. The fewer Of
these lines there are, and the more
nearly parallel. the more more accu-
rate the plane"
Mr.. Kahler called attention TO a Gu
rious class Of work which he bad done
for the astrpphysical observatory Of
Smithsonian by producing a prism
lnclosed ia a hermetically sealed glass
Jar. This prism was. apparently. Of