Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1891-11-18
HOW TO STUDY THE STARS.
Hints for Those Who Would Use the Tele-
scope-First Train the Eye to Observa-
ton Through the Lenses-Sizes That
Give the Ro.x r2oaulfs

scope-First Train the Eye to Observa.
ton Through the Lenses-Sizes That
Give the Best Results.
| Amateur astronomers who are desirous OF
| studying the mysteries of the heavens are
| quite apt at the very outset OF. their investi-
| cations to become disappointed if not dis.
gusted, ,on account of difficulties encountered
In selecting the proper glass for their obser'
| vat1ons. In addition to the mechanical
| troubles, says q writer in the New York
Times, sense of disappointment often sets
IN shortlyafter one has begun as telescope
observer. for everything seems so much
smaller than was anticipated, and so little
seems visible as compared with what
others have seen and described. 1t re-
| qu1res some little time for the average novice
to realize that he has in reality but just
| begun to educate his eyes. Even those who
nave mad considerable practice in other
branches of telescopic work experience the
| same sensation when they first turn their at
tent1on to new features.
Thus the most experienced observer OF
| double stars frequently finds himself quite
| at loss when he begins to observe plane
tary details. The wisest use, therefore, that
beginner can make of his telescope for
the first two years is to turn it first on one
body and then on another, until he can with
hav already seen in similar objects. He
thus learns how best to use his telescope, he
gains experience in interpreting what he
sees and in what to look for, and, above all,
| he educates his eye. Having at the end of
this period learned what others have al
ready done, he is then better qualified to try
to do something for himself.
In the Sixteenth Century.
-Digge's works in 1891 speak of the use
OF proportional mirrors placed at convent.
ent angles for the discovery of things afar
on. 1t is stated that men could even then
be recognized at distance of three miles,
and that the superscription on coins de-
posted in fields adjacent to the position in
which the glass was mounted could easily
be read. Calico knew nothing of it until
1903, when he was casually informed from
Germany. He then made one for himself
that magnified three times, and afterward
made larger one that was ten times the
power of the first, and with this he discov-
cred the spots on the sun. the satellites of
Jupiter, and the phases of Venus. These
were dioptric instruments, and the great
length that was found necessary to make
glasses of this type resulted in the rejecting
telescope being introduced.
when one examines into the component
parts OF the telescope, he can readily see
how the instrument may be considered one
of human knowledge. 1t is work in which,
by following unconsciously the plan of
nature in the formation OF the eye, men
have come nearest to the construction of
new organ of sense, and by means of which
they have extended their views and re-
searches far beyond the limits of their own
globe. Enabling the eye to penetrate into
the immensity of space and to become, as it
were, familiar with other worlds placed at
almost immeasurable distances from it. the
telescope has revealed an inflnitude Of celes-
t1al bodies whose existence must forever
have remained unknown but for its inven-
tiOn.
A Difference in Telescopes.
Interesting though the inquiries may be
as to who was the first inventor of the Top
tic tube" the object at present held in
view is of a somewhat more practical na-
ture, and deals more with how to use it from
the piazza or housetop in the pursuit of Il
more interesting knowledge of the heavenly
bodies than can be had with unaided vision
One is frequently at a loss to know what are
the chief differences between the astronom-
ical and the terrestrial instruments, and
how to make the one telescope answer the
dual purpose. While there are many feat
ures in the glasses used by professionals that
are not found in those in general service, it
is fairly within reasonable bounds to saw
that the primary dissimilarity is in the eye
piece. 1t makes not particle of difference
to the astronomer whether the
moon, sun, planet lane &c or L star is upside
ordinary mortal prefers seeing terrestrial or
marine objects right side up. Every ordi-
nary lens possesses the great disadvantage
of having both chromatic and spherical
alteration, which must be corrected before
satisfactory fine observing can be attempted.
This difficulty is ordinarily overcome by
using two lenses of such focal lengths, OF at
such a distance apart that each counter
acts the defects of the other.
Rejecting telescopes operate best in the
open air, or, at least, in situation where
they are nearly sheltered from the wind.
From their form they are always mounted
on low stands, and can easily be covered with
a fiat roof not more than six feet high. The
therefore, one with roof which runs back
over at least one-half of the dome. Refrac-
tors are necessarily mounted on much
higher stands, so that they require drum
shaped roof Either of these can be erected
at moderate cost on the housetop or on firm
ground.
The Most Useful Sizes.
The most suitable series of magnifying
powers for celestial telescopes are Is, 80, As,
GO and go to the inch of aperture. very
low power eyepiece, with a large field Of view
and magnifying about 40 d1ameters, is useful
for finding objects. The greater number Of
nebula, comets and a few wide double stars
require the power of 15 to the inch of aper-
ture; or, If bright enough to bear it, the
power of 40 to the inch may be used. For the
sun the power of 80 to the inch is the only
one that will be of much service. Mercury
and Venus at daylight will also require the
same power. So will Saturn; but the satel-
lites of Saturn will be best seen with the
next higher power Jupiter, Uranus and
Neptune should have 45 20 the inch, and at
times Jupiter should have the next higher
power. Mars generally requires power of
80 to the inch to show the markings well,
and this must also be used with Mercury
and Venus after sunset. For the moon a
power of 45 will be found best for objects
unless seen under high illumination, as when
the moon approaches full in which case 80
or even 30 will be required. Occasionally in
very steady air, telescope will bear still
higher power than these, but even then but
very little more can be made out
In using ones telescope the first thing to
be remembered is that if anything be worth
watching it is worth noting. Every Observa-
tiOn should be accompanied by full details
as time, weather, etc. Whenever possible
sketch should accompany the description.
No matter how rough or imperfect this
sketch may be as long as 1t is accurate, the
artistic features may be done away with
and coloring are always OF i'm
and the date is q great necessity,
for without it the observation is almost val
uelesS.
Beware of "cheap Johns" If one wishes
a really good instrument he must be pre-
pared to pay reasonable price for it.
HAZING FOR GIRLS.