New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1897-06-27
AN HOUR WITH A STAR GAZER
PEEPS INTO AND FROM AN ASTRONOMI-
CAL OBSERVATORY
SOME ATTACHMENTS TO A TEIJ;sCopr-ytIAT
THE ASTRONOMER DOHS by DAY-MANY
MATHEMATICAL. DETAILS TO BE
WORKED OUT.


Ut is deemed good policy at some OF the lead
ing astronomical observatores in this country IN
adniit the public on evening every week al
thoush such n plan interrupts the regular work
Oh the institution An interview with a big teIe-
scope on these occasions is apt to be diSappont-
ihS' however. no matter how obliging the astron-
o"crS are; because the explanations and the
time must he divided up among a large number
oi people But If the outsider is fortunate enough
to have private "pulI' with the authorities,
and has a little smattcring of knowledge the
SUBJECT perhaps he can gain admission for an
hour or two on some other evening of the week,
and thus secure much more exclusive privileges. !
what takes place at such time will be more
readily understood by the visitor if he first give
some attention to a few of the attachments to
the mann instrument. which. at first glance seem
to be confusngly numerous. There are one or
more very small telescopes. for instance mount
cd on the principal tube and pointing in exactly
the same direction. If you look into q these
you can see much larger are" 81 sky than If
you looked into the mai" glass. The small one. |
therefore, is nr~' more convenient for finding !
any par, uiar celestial object. although it does
re give as great magnification
TAXING AIM
Instead of sweeping the skies in the general !
neighh'rhood of the star or comet ncbula he |
is hunting fui. perhaps the astronomer will take
ann by means of what are called the circles" |
These are two in number. very carefully Gradu- |
ated To- degrees and minutes. and mounted
that ON" indicates the latitude Of the heavens !
and the other the longitude. The former is !
affixed to the axis which allows Of up-and- |
down Cor north and SOUTH movement to the |
outer end of the telescope: and the latter to the
axis which permits sweep from east to west. !
The presiding genius Of the observatory calls |
them tie "deClinatiun'' and right ascension" |
circles II has set the telescope accurately by
these means. after having looked up the post !
office address of the star or comet or nebula in |
question from ono OF his standard guide books. !
he will have brought the object into the field of
his big telescope at once. without making use |
OF the it'll finder at all. There is mechanism
(whccls. rods and gearing that enables to |
move the instrument in this way without leaving |
the eye end. Resides this apparatus for quick |
shifting. there is a slow motion screw where |
with the observer effects more delicate adjust |
ment. lie then tiEhtcns certain clamps. and |
thereafter the driving clock situated in the great
pillar which supports the telescope, keeps the in
strument trained the object to be studied.
Finally, it is necessary to slide the eyepiece |
in cut of the great barrel. in order to get just
the right focus for the subject in hard and for |,
tn particular observer. This is Il exquisite |
task. generally. than any other and failure To
perform it satisfactorily results in much dis
appointment To the unini;iated visitor to an OBJ
servatory. Even the experienced astronomer
when h has nearly reached the limit of his own
visual sensblity. sometimes discovers that the
change of a hair s-bread;h in the focus will pro-
duCe marvellous effects.
The eyepieCe may be removed and replaced
by one of the higher or lower maGnifying power
according to the needs If the moment. If the
air, though almost calm at the earth'S surface
is disturbed aloft, there will be some unsteadi-
ness in the images. and this is increased the
higher the power of the cyepiece. In order
get satisfactory definition. therefore, the practi-
cal working astronomer uses much lower powers
than the instrument is supposed to be adapted to-
THINGS TO ADMIRE.
When the favored visitor gets his first glimpse
of the heavens through "A big glass. he hardly
knows which to admire most. the increased brill
fancy of the brighter stars like Sirius. Arcturus
and Vega, or tine astonishing multiplicatio of !
the number of the fainter ones. He is almost !
sure To be surprised, though. at finding that the
diauctrrS Of even the larger are not sensiblv
incrca: ed. Even the planets which are suscrpti-
bic OF maSnitCation. q" not quite come up To |
his preconCeived ideas in respect TO size some, |
OF them, though, like Jupiter and Mars will re-
veal interesting markings. Saturn has his rings
as well as a family of moons. wherewith To pro- |
woke wonder and pleasure. Venus reminds one
OF a small crescent moon. Mr.. Barnard once
II 4