The morning news. [volume] (Savannah, Ga.) 1887-1900, 1894-03-25
ASTRONOMY WITH. A MICRO
SCOPE
If Gathman is Right We May See the
Hairs on the Head Of the Man in the
lm the ChIcago DalIy Trlhnnn.

For 800, 600 ! will undertake TO con-
struct a telescope with an objective ten
feet in diameter, better in every respect
in proportion than the forty-inch 100000
Yerles telescope, and to finish it sooner
For a proportionately larger sum / will
undertake to construct a telescope with
an objective 100 feet in diameter more
efficient in proportion for every scientific
purpose than the Lick or Yerkes tele-
scope There is no reason in telescopic
science why we should not see the iuhab-
ttauts OF Mars and see TO pick up pin on
the NOON
This is the bold but intelligent ut
terance of Louis Gathman an amateur
optician, astronomer, scientist and in
ventor, of the North Side. NJ. Gathman
has for twenty years been possessed with
the idea that great improvement could
be made in telescope lenses, especially in
respect to size. His doctrine is that
wherever there is an urgent need for a
non-existent thing, that thing can be dis
covered. Accordingly he has chafed a
good deal under the idea that telescopes
had reached their ultimate size on ac-
count of the impossibility of casting large
pieces of glass without bubbles, as well as
other inhrmities inseparable from glass
in large pieces. His dream has always
been that Tense could be constructed in
sections. Two years ago he completed
his discovery and made a working model
Since that time he has kept his discovery
secret In order TO secure his patent rights
first in Germany and then in this coun-
try. As his German patent has been is
sued, and as his American patent is as
good as secured he has had for some time
no motive for secrecy.
Mr.. Gathman's discovery is in brief,
that lens that is made in sections can be-
made as correct as any other lens, pro-
vided the sections are separated by dull,
black partitions, which prevent an inter-
reflection of light from their margins.
The sensitiveness Of a lens to such dis
turbances is well understood. A single
air bubble, however small, in lens, how
ever large, renders it worthless, the rea-
son being that it splits aud refracts GER
tain rays of light and causes confusion
at the focal point. Mr. Gathman's theory
is that ii tho bubble is bored out and the
opening filled with dull, black material
the lens will be perfect again, but no
thinks there is no use going TO this trouble
when lenses can be made in small sections
and the perfection of each section assured
before it is used
This principle has for many years been
applied to retectors. There are not only
search light rehectors, but refectors OF
rejecting telescopes, constructed in sec
tions. These reflectors have been found
to be as good as any others, aud the wish
has constantly been expressed that the
principle were applicable to lenses and to
refracting telescopes, for rejecting tele-
scopes are comparatively worthless But
opticians and astronomers were so well
satisfied a priori that the principle
was inapplicable to lenses that thew
would not condescend to experiment with
il. Not so, however, " It'll Mr.. Gathmau.
He reasoned that if the interrefiection OF
light was the only obstacle, that could
easily be prevented by interposing nom
rejecting surfaces between the sections
Of the lenses He tried it, and was sue
cessful In his first experiments
Mr. Gathman divided his lenses
into wedged-shaped sections with a
circular section at the center, leaving no
interstices, except from the insertion of a
blackened metallic rim half an inch wide
between them. Subsequently he found
it better to leave wide openings between
the sections, the object being to allow o
free circulation of air, which would
equalize che temperature in front and
rear Of the lens, and in that way prevent
sweating. In this way he was led to
make the sections circular and of differ
ent sizes. The seven and one-half inch
lens Of the telescope which he now uses
in his observatory is made on this plan
1t has circular section in the center, six
circular sections of the same size ar
ranged around it, and then six smaller
outside the larger six. The result is that
objects seen through this telescope are
brighter and better defined than when its
objective was a single piece.
This last lens is apt to produce the i'm
preston that 1t is an assemblage of small
lenses, but that would be obviously un-
scientific, and is far from the fact Each
section is shaped exactly as If it had been
stamped out Of the large lens; and that
fact makes one curious at once to know
how they can be ground accurately to fit
in their several places. But this is a
matter Of no difficulty. Mr.. Gathman
takes number of pieces of glass and pol
lshes them, in any plane, so as to see
whether they are perfectly translucent.
Then he gives them their circular out
line. He next arranges them within a
circle of the desired size andpours melted
sulphur between them. When the sui
phur has hardened the pieces of glass are
held firmly together in the positions they
will occupy in the lens They are then
all ground at the same time, like single
piece.
1t is understood, of course, that the OBJ
jective of a telescope consists really Of
two lenses, one in front of the other. The
outer one is double-conVex and is made of
plate glass, the inner one is concavo-con-
vex and is made of crown glass. They
fit together like single piece. Mr.. Gath
man manufactures MS CONCaNO-HOnVGX
lens in the same way as his double convex
lens, but separately, of course. In one
of his lenses each section. though looking
like single piece, has an outer and an
inner layer
The advantages of MIR Gathman's in
vention are wonderful and incalculable.
The first is that all limitation on the sire
and power Of telescopes is completely
done away with. The manufacture OF
the Yerkes 40-inch objective is regarded
as daring feat and a wonderful success,
which will probably mark the ne plus
ultra Of astronomical exploration. The
main reason is that the larger lens is
made the more difficult it becomes to ex-
clude air bubbles. But there are also
other difficulties attending large lenses.
They are greatly affected by expansion
and confusion, and when set up on edge a
long time they are found to sag, or mash
together, of their own weight, so as to in
terfere with their correctness. Now, a
lens made in sections has none of these
iniirmites, and it is altogether possible
TO make it 100 yards in diameter ii de-
sired