The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1897-06-28


observatory was constructed, and now we
have this forty-inch objective which Mr.
Clark had fortunately completed and de-
liXred before he passed from earth.
BELIEVER IN BIG TELESCOPES.
Mr.. Clark told me that he had always
been a believer in large telescopes for
special work. He had had much expert
ence with them. and ii was from testing
such instruments that he became con-
WINGED that larger ones are needed to make
original discoveries, such as satellites to
planets and faint companions 10 bright
stars, in fact. TO any stars, well for
studying nebulae He held that for astro-
physical work they are vastly hyperion to
smaller glasses. THE trouble that early
opticians experienced IN procuring good
discs OF glass seems To have passed away.
sald ne, ana we are now aole 10 procure
being the time required TO make them and
the money To pay Tor them.
1t was then / asked Mr.. Clark what he
thought OF the future possibilities IN the
construction of still larger telescopes, and
here is his reply; IT is my idea that those
OF the future Will not be retiectorS but re-
tractors. Z do mot underestimate the value
of the great discoveries made with reflect
ing telescopes. nor do 4 say anything
against those who make and work them.
but my experience has convinced that
the reflector is extremely sensitive to any
changes either of temperature or air cur
rents more particularly to Texture. 1t
is true the refractor is also affected by
so injurious to the definition
1t came out IN this conversation that
good discs OF any size. both crown and
hint. may now be procured, notably from
NJ. Mantois, of the Rue Lebrun, Paris
these Yerkes glasses were cast by him
and all that is required IS "A Skllful optlclan
to prepare them He must be an artist"
remarked Mr.. Clark. IAN artist as to light
and shade. and in color also the last OF
the very best correction of the Chromatic
alteration. AS in the light and shade we
search for and locate the spherical aberra-
fer
for the chromatic corrections. This is a
difficult task, and its difficulty Increases
with the size of the disc"
Mr.. Clark declared that personally he did
not believe this work could ever be accom-
plished by machinery. 1t was true, he ad-
mitted, that some of the rough work and
first polishing might be done by machinery
and, indeed, his men had thus polished all
their large surfaces in a preliminary way
but the fine grinding and smoothing viii
always have to be dee e with human hands
1t is after the first machine polishing is
done, and when the glass appears 10 be
finished, that what MIR. Clark called the
artistic work begins.
1t is not necessary to restate here the
views expressed by that master workman
as to the requirements for making large
lenses, both crown and flint, but I Vil
say that he next expressed what he
thought of a greater telescope. He said
that he not only believed it would be a
refractor but that its size would progress
sively increase. 1T will be mounted equa-
torially, and be provided with the best driv-
ing clock that can be devised. l am in
favor OF the long polar axis, known as the
English plan, for such an instrument. and
for several reasons, the main one be ing that
of stability. The style of plan which Amer
leans have generally adopted in the case
of my large telescopes is not as stable as
it ought to be"
THE NEW ASTRONOMY.
AS for the benefits to be obtained from
these great glasses of the future MIR. Clark
thought that much would depend on
the localities in which they were placed.
IT,
stances a great telescope will produce great
results, but those results will be ever so
much greater if it is used under the best
possible conditions The increase in size
of this Yerkes refractor is a fact and with
it will come large acquisition to our present
stock of knowledge. The new astronomy.
well as the old. demands more power.
and yet size and preparation are not the
only requisites of greater telescopes. There
are civil engineers, as we'll as opticians, TO
be consulted, for the construction OF a
building in which telescope is to be placed
is second in Importance only 10 that Of the
instrument itself"
This ended our conversation at that time
and ] saw Mr.. Clark no more, though he
promised to tell me of the practical work
ings of the immense lens after the tee-
scope had been placed in the observatory
on Lake Geneva. He had not had time to
send for me since his return, when death
struck him suddenly down, and another ia
nous man, a genius, was lost TO Massa-
chusetts. AS a maker of large lens he
stood alone while as a maker of other tel
escopic glasses he was equal to any man
in Europe. Nevertheless, and during sew
eral years, he worked without receiving the
slightest ref0 ciad ecen}c or ednc
quarter. It may be said that he worked in
entire obscurity. Even during recent times
when his house had been admitted by the
highest scientific authorities in the world
to be at the very head and front or all
lens makers, he received but scant recogni-
ton in his own country, and from our
much-boasted government none whatever
Had he been a Frenchnan or an Ehg IN
man or German or other foreigner ms
native land would have been as proud or
him as Great Britain is of Newton. as the
French Republic is of all her many serV-
ants.
Just a few words now on the question OF
the future application or the 0puc TO the
drawing of stars near to us. For 1t must
be remembered that to increase the size
of an object to draw it nearer is the
same thing. Thus, a glass which increases
a thing four times if directed at inscrip-
ton 100 yards distant, shows 1t as II 1t
were at twenty-five yards. Add, ana TINS
IS the result of experience, that the normal
enlargement applicable TO astronomical
glasses is two times per mn mb,,e on on ohe
iective of O.24 GA centimetres) gives nor
NAL enlargement of ASO times; an obJectlVe
of o 80 $50 centimetres) gives 1t 1900 times;
an objective of l meter gives at 1000 times,
Therefore this new Yerkes lens, with
its objective of $50 normally enlarges, or,
what is the same thing, draws near JUN
times Before this latest example or sklIed
prepared the best instruments coutd, Wnen
aimed at the moon, which IS 20OO0 miles
away bring that satellite as near as though
it were only 40 miles distant. Even better
than that was done where the atmosphere
was pure and perfectly calm, the ehIarse-
ment of 2 900 being increased TO 300 times
Consequently, If, with actual instruments,
astronomers could under certain circumo
stances count on engagements or 5.V0
times there is no doubt whatever but mat
they may under similar circums tances; OBJ
tain an enlargement of at least 4,0g9 times
with this Chicago lens, the normal or whlecih
Is only 00O The distance, 100000 being d.
vided by 1000 gives up 60, and that IS the
number of miles from Lake Geneva 10 me
moon via the new telescope.
with the aid of photography, using the
ingenious process invented at the Prague
observatory, which enlarges ten times OF
more, we shall be able to see luaary iahqs
scapes only six or seven miles away. II
we can do that with the moon. perhaps we
shall soon know something DEFINITE ABOUT
those canals on Mars. or the constitution
of the rings round Saturn, and maybe We
shall soon be able to solve the problem OK
Jupiters satellites.
Drowned Under Barge.
CINCINNATI June 27.-This evening