New-York daily tribune. [volume] (New-York [N.Y.]) 1842-1866, 1847-12-28
ASTRONOMY.
LECTURE y....BY PROFESSOR MITCHELL.
Rsgsrsd fsl n. Ili9as bg I HIM ssrr Plenssr sils-

Gs.os ps4tsl Discovery Of iis ainss-Diss,s very Of
10 -stel.tes- Dimensions Of the Enss-tiow we're tneT
Fir.t Placse The e. and What srs hey Their Adiiy
proved By Oeculf1f OF Sars, and their shadows 90
H. Piane'-Ho- their Positions are M,infainsd TX
piaired Thrse Kinds Of Eq1iltTiau-L Places Theory
II the Rings-Thsir Equilibrium Explsined-La Places
Theory q me Formation q -yst, us unity Of ms
Thsory-L0nE Equation Of Jupiter and -sfnrn the Re
sult n their Colcdent Periodic Tns-Ifs Effects upoa
Syftern-Oiner Singulsriii-s 10 ssturns Motions
s.dus-Of the SATELLITES Of that Plsnetrher Exrrsor-
binary POSITIONS ana Msvemeu;s-Bst Three q them
turbsuons ObssTved-LevsrriefHi Singular Position
His Prediction Of the Time q Msrearys Irsnst-He
Attempts Solution Of the PerturDAfi0ns Of JANUS
HIS Csicuatious-Their Doubtful Tn
un plant Success in the Discovery Of New Planet
AdAnis's Simultaneous ConputsiioDs-The Planet found
70 Disasree win the Cacuatiers- aikef Cenplte.
ton 0f - OrDt-ocratiny Of la Lande's Catalogue %
S.srs-The Planet Of Faet net the Panet Of TAeoryIts
Mass Appfoximsteo py discovery o. oatse- siluf-
Of Leverrer and Aosms-IheiT Problem not the Proc
lem n Naturs-sup position OF Grolp al Plnst- %
AdarA
LADIES AyD GEsTLENEs If il were possible
r me 10 transport you TO night to the distance o.
ninety millions Of miles in direction passing
through the Suns anDual track, and could there To-
cate you your sight would in short time be greet
ed with a most wonderful and sublime exhibition.
You would see approaching you magnificent
World rapidly Nhirling upon its own axis. Around
this vast central orb you would find number Of
tesutful rings Of light: these too, would be seen
10 be Whiring around with surprising velocity. On
the outside Of this again you would mark, as the
object approached nearer and nearer, no less than
seven subordinate worlds sweeping around the
great central orb end with il rolling through Space.
This is the Planet Saturn with It's rings and moons
and tits to this object propose, primarily to call
your attention 10 night 1t is the most distant Of
O. a. al fof no An -
is the longest, and its NOV ement the slowest aud
most majestic. Up to the time Of the discovery OF
the telescope the wonderful characteristics which
mark this object were unknown, but when Galieo
directed his space -annihatng tube to its investi-
cation he announced 10 the world that he found ga
turn 20 be triple--thst there were what be CON
ceivei 10 be two globes attached 10 the main body.
one on the right and the other on the left. But
these were oIly the projections OF those mighty
rings standing oblque 10 the line Of vision, and
seen imperectly through his glass which magnihed
but twenty or thirty times They appeared 70 him
10 be projections or globes attached 10 opposite
sides Of the main body Of the planet As the tele-
scope was improved, these projections bad their
true ch atacter revealed. and It was seen that Hat
annulus or ring. passed entirely around the globe
of tue planet aud was separated by certain
amount Of distance. As the power OF the telescope
was increased. and more minute Investigations
were made. 10 was found that the broad ring was
divided into two rings and IN modern times, with
in the last ie. years, by the aid OF the mighty teie-
scopes now engaged In astronomical Investigations
il has been ascsrtained that the outer Of these
rings is again divided, and there are no less than
three which encircle the planet. The satellites
were not discovered till long after the time Of Gal
heo. Ia the year 1865. we learn, one OF them was
seen: and shortly after four more were announced.
Then Sir WIN. Herschel with his forty feet rehec'
tor detects the two minute bodies that seem to
cling closely t. the edge Of the ring and are scarcely
ever visible in consequence OF the intense lignt
thrown out by the Planet. Here, then, we have
three rings aud seven satellites, or moons, which
belong to TINS most wonderful sphere and reniem-
Der that all these are sweeping with the planet
through space aud is --hoes LIS circle about tho
Sun they move regularly with IL, obedIent entirely
10 It's control But what are these mighty rings
The exterior diameter OF the outer one Is no less
than III 500 miles their breadth, measured entire
Is across both rings is 30 600 miles, and therthck
ness is one hundred miles. How strangely are they
constituted how wonderfully are they poised IN
spscei We can understand the original move
nent oil all the Planets with the exception OF ga
turn we can form some idea how this Earth whlch
we know TO be gObular, might have been projected
bv tina Hand of Omnipotence, and caused 70 revOlve
ia its ORBIT about the Sun but how was 1t that
those stupendous rings were hurled In such a man
ner as 10 acquire that stability OF movement which
holds them steady to the action OF the central plan
ct and at the same time rolls them onward through
Space with the immense velocity with which they
noyel This portion on our Sy stem battles ell con
lecture; it rises entirely above the comprehension
of the human mind While we make some rough
approximation 10 the notion as 20 how the other
planets might have been launched In Space, we
can form no conception OF the manner In which this
one eos started in its career.
But what are these mighty rings Are they
merely mass of light Are they projections OF
the atmosphere belonging 10 the panetl Are they
portions flung out by the centrifugal force, and
thus in some sense held steady in their position =
Are they solid bodesl | answer; They are solid
bodies and of the same material that comPoses
the body OF the planet.
Rat how do we know this In the first place,
we know them to be solid because, as the planet
with it's rings passes between US and distant groups
of stars such stars are first Occulted by these rings
Ia the next place, they are not transpare IN any
degree because Of the fact that at the distance oil
nine hundred millions OF miles We are able 10 mark
the space Of the shadows cast by these rings on the
body of the planet Night after night, month after
month, aud now almost year after year have l
watched with my eyes the phases OF these
wonderful shadows. They are deep and dark,
much blacker than any shadow you find cast upon
the surface OF the Earth
But again they are able TO exhibit the same
characteristics themselves and in certain positions
We fad the light OF the Sun falling upon the body
Of the planet. which casts shadow upon the
broad surface Of these rings and though we have
the same backness as before, here Is the distinct
shadow cast by the Planet upon the ring. Now,
as we watch them attentivey We IND invariably
that these shadows depend upon the position OF the
Sun and certain positions Of the planet and rnss'
lust AZ the shadows which are cast upon the sur
face OF the arm depend upon the position Of the
source of light, so do these and they follow with
the same precision and accuracy the movement OF
the source Of light that shadows do upon the Earth
and hence We cannot be deceived
The space by which the interior ring IS sepsra'
ted from the body OF the planet Is no less than
twenty thousand miles, and the breadth OF the ring
is about tea thousand miles before we reach thar
space which separates II from the next rinS, and
50 onward till we pass the outer one, OF which
have Just spoken
Now how is IL that these rings are held stable
How is it that they, detached from the body Of the
pl.net are carried with that planet through Space
The stability Of the rings Of saturn Is perhaps one
of the most difficult and perplexing problems for
the Astronomer, and l would do injustice 10 the
subject were to pass over il without attempting
To give some notion OF this singular problem And
before / begin permit me TO explain the TACT inst
there are three different kinds OF equilibrium Tor
ia the understanding OF this will be involved the
understanding of the explanation which am ABOUT
to make will attempt 10 exhibit these three on
L -. 81. hU he