The morning news. [volume] (Savannah, Ga.) 1887-1900, 1900-05-19

ism. But 1t had a heavy work to do, car
rying the massive telescope with its
weighty lenses, and nesded to be CORE
srondngly stror. IL had a driving
weight of about 1900 pounds, and was 50
powerful that turning the telescope af-
fected it no more than. does the hour
hand of an ordinary clock the mechan-
ism within its case.
The final test of the whole adiustrne ut
consisted in noting whether stars once
brought into the telescope field of WV
could be maintained there automatically
by means of the clock. This object hav-
ing been attained successfully. the ins'rr-
ment stood ready TO be used in the routine
business of the observatory.
Before leaving the subject of telescope
mountings, we must mention the giant in
strument now in course Of construction al
Paris, and which IL 20 be finished In time
for this years exposition. 1t is intended to
have ii set up for actual use. so that vis-
tors VIII be able 10 examine person ly
what can be seen with the largest tele-
scope the world as ever known. There has
been for many years a sort of quiet int
national compS tition in the matter Of =
Economical instruments. Americans h ave
every reason 70 take pride in the fact tnat
this country has always possessed the m
strument of greatest power Perhaps the
most famous of all telescope lens makers
was the late Avian Clark of Cambridge
port Mass. lie and his son FURNISHED
large lenses fo7 the United States qhi
Russian governments. nor the Lick Ob5er-
yatory, and finally for the great 40-inCh
Chicago. This last instrument is at pres
ent the largest I'm existence; but 1t Will be
surpassed by the new one at Paris.
The most important desiderltum in lele-
scopes is great light gathering power; and
this depends simply on the size # the
lens. The Yerkes glass. which is 40 in h IS
across, possesses this power in a very high
degree But. instead Of 10. the Paris n
strument Is to be a little more than 20
inches in size, which will make the light
gathering power one-ha.f as large again
as that of the Chicago glass.
But the most remarkable popularity at
Paris is the proposed extraordinary length
of the entire instrument. The tube Is to
be 1871 feet long, or more than three times
the length of any existing telescope There
are certain optical reasons in favor OF
these huge proportions. II is impossible
for human hands to grind an absolutely
perfect lens. and the remaining unaVoid-
able imperfections have the least harmful
effect if things are arranged so as to put
the Observers eye as far as possible from
the other end of the tube. The limit upon
length has been imposed hitherto by the
purely mechanical difficulty of handling
instruments of excessive weight. 1t is
simply a matter of mechanical engineer
ing.
Al Paris this objection will be avoided
rather than overcome. II is proposed TO
make the tube immovuble and to mount it
horizontally in fixed position. Then,
in order to observe different parts of the
sky a mirror will be placed in front of
the telescope and the sky examined by
fAf, l. rxyt1 ha
provided with polar axis and clockwork
so as to accomplish the same result as
If the telescope itself could move. The
only fault in this arrangement is its in
creased compleXity. The mirror ID an ad-
ditional glass TO grind and polish, and if
they do not succeed in making 1t perfectly
fat, slight distortions will be produced in
the star-images under observation. As
tronomers are looking forward with much
concern TO the scientific success or failure
of this great instrument, Let us hope that
it will help to throw light upon some of
the many astronomicalproblems awaiting
solution in the new century.
The following predictions give the posi-
tons of the principal considerations at
p. M, April To- 1900 but they will also
be found approximately correct at the
same hour throughout the month:
Orion is now about TO set in the western
horizon, Auriga the charioteer, and twin
starred Genlnl hanR ABOVE MIN, nearly
halfway up to the zenith. The great dog
star, Sirius, is also down near the horizon.
but the little dog star Procyon, is sin
about half way up to the zenith, a little
south of west. Leo Is on the meridian,
about due south, up nearly three-fifths
of the distance from horizon to zenith. 1t
shows a sickle-shapeJ figure with open
blade turned to the right, and the handle
straight up and down. In that handle
glows the gen-star, Regulus. Virgo is in
the southeast, one-third of the way up 10
the zenith. The Great Bear is overhead,
just above the pole.
OF the planets, Venus Is evening star,
and just after sunset will be found in the
western sky, about halfway UP to the
zenith. 1t is near the Pleiades group. es-
pecially in the early part of the month.
The closest approach VIII be on April 4,
Mercury Is morning star in the latter half
of the month. There will be a good OPP
portunlty to see it on the 2ist, near the
eastern horizon just before sunrise Jupi-
ter and Saturn are morning stars, and
just before sunrise are little west of
south, above the horizon from one-fifth to
one-quarter Of the distance up to the
zenith On April 20 a rather unimportant
shower of meteors is expected. The moon
will pass close to Venus on the second, to
Jupiter on the eighteenth, and to Saturn
on the Goth