, 1873-11-19


curing opportunity to institute direct compari.
Sons between two of the most interesting Objects
OF astronomical study in tho whole hoayons.
After tho sun and moon, ttoro ara nono
that havo boon scanned moro pcrsislcntly
with tclescoplo oyo; and probably mono
which have yielded 30 rich harvest Of knowl-
odgo Us tic reward OF persovorine toll. Tho
smallest, Havo ono, aud tue largost, with ono OK
ception. of all the planetary bodies known to tho
ancicnts, aud widely s,lndored by distance, as
different in size, they present strikingly dis.
tinct peculiartica of appearance, oven to tho
naked oyo. But much moro wonderful md
boautiful are the contrasts observable through
tho toloscopio tubo, whorowith nun has bridged
the inmcnsties Of space, and brought tho far
distant stars almost within hail Of our littlo
world.
Comparison is tho koy TO Knowledge. It is
only when VIC bring similar objects close to-
gethor before tho material or tho mental oyo
that VIC can detect slight differences Of color, or
magnitude, or quality aud tho properties OF
disa!lmisar objects nro moro strongly appreciated
because more yiyialy presented, when in CON
trast. Tho more accurate tho comparison tho
moro precise nre our ideas of difference, and tic
greator is our ability todone tho characteristics
OF individual objects. On tho other hand, COM
pnr1son leads to analogy aud from tho obsorya-
tion md study Of eyBtomatizcd facts We arrlyo
ut knowledge Of what we call law, either of dis.
tribution OF Of force. It is thus TINT We become
wiao.
Tile present position Of Mars and Saturn Is
not 60 favorable for close observation and CON-
parison, Us is sometimes mot with On account
OF their great Southern declination (snturu 81 Q,
and Mars "a J thoy do not attain m altitude
from the horizon sufficient to cnnblo Us to 500
thom. except through portion Of tho dust ond
vapor that continually riscs from laud and water.
mingllng with the lower atmosphere, and caus-
ing diffraction Of tho light rays, and consequent
uisteal'neRs Of yision. And it is unfortunately
tho case that tho higher tho magnifyinp mower
We employ With tho telescope, the more arc
taoso disturbing ' effects ncreased 90 that at
Saturn are obtained with eyo pieces Of low
power. It ia as bad. il not worso. with tbo
spectroscopo,. tho atmospheric lines being go
abundant Mt low attitudes as to cause the most
annoying ann confusion: dozon years honco alars
mood OF the constellation Gemini not moro
than 20 degrees from our zonith. Mars may bo
studied alone adyantagoously in 1877, and 1870.
hl.oing IN opposition! to- tic sun worry near
.no tho pSsl,lloilon point in tho last nnmod
eauinoctial, but the plane Of his magnificent
rings will be go nearly in tic direction Of fhn
earth TINT VIC shall DO able to nee little besides
tho planet and bis satellites. Wo may, how
epGr end IN maze th many interesting observations now
at from former work in this direction.
An apparent difference In size between Mars
and Saturn is easily perceived. Though Mnrs
ID a ~, only l46 600 ooo mieB distant from tho
oasth @ ~ at tue present timo, whilo Saturn is 9G2
away. yet saturn's apparent aroa ia 5]6 times !
tho greatest, hs apparent acmidian,etor being
4 75 seconds, wh1o that Of Mars il 9 . seconds,
Ihts shows an enormous difference in tho d. |
ot IN object decreasing with IN incresse in its its
distance. When wo apply our colostial measur-
ms rod, We find that Saturn has diameter of |
q 25o mtlea, or more than nino times that of |
.no o oarth, making hls rolativo volume NJ ncarly
IN the other hand, has a diameter Of hut 4.O2o
miles. being little more than ono-half, Or a VOL
lmo ono-eighth TINT of tho earth 80 that tho |
9ulA aa OF Saturn is to that Of Mars as moro than
1000 to1.
:, We may note, secondly, that although the
1lso OF Saturn coycrs moro than five times as |
much angular surface as Mars, vet tho intensity
y their light ls at present very nearly eaua[
1enco It follows that We roccvo about 1.-Two tilnos
- - m1ch lGht from Mars as from ono-hfth part
u tho apparent surface of Saturn mud very
nucll more than that proportion from IN egual
lumber Of aquare miles on Saturn. Tho reason
or tllls difference is that IN tho one oage tho
un light trayols OK timos tho radius
II the oartla orbit, and buck throngh
wen greater distanco, who in the other, It's
otal distance travelled, back and forth, IL only
;oont aoo, ooo, 600 miles. Tho Journey Of tic
ight ray that enables us to 500 Saturn ie gix
imes creator than that by tic aid Of Which wo
liscern Mars. And We know that the intensity
u light t'ininishcs as tho square Of tho distance
''"N~ ]
Tho noat striking difference, oyon to lilo naked
70. 10 ono OF color; when no look at them
hrough Ions tue dltforonce s much more an
aren't. ,i Mars 10 blood-rod, which fact uu.louht-
uly "as tao original reaaon Of his beiny called
ao = you OF war W tho ancient mythologfstg. and
u su'geSy ny their Successors. Satuln'B light Is
emily found not far from tho midfilo n t.o aolar
poctrnm, having lingo Of blue though not no
eclaealy blue gu represented by tho ancient as-
Observations were mado a fnw
oars ago upon Mars ind Saturn with an olcc.
romotor, by an English Investigator WIN o1aim-
. to hnyo noted that tho lignt from Mars do.
ectod tue index IN tho positive dIrcotlon. whilo
ne y !lett from Saturn gaye the contrary result. |
th's bo fact, it IL . highly suggeptsyo ono
u beara strongly on the psayio,Hly e,Hpeotoi
nalogy Of rcd with positive electricity an1 hlno
tn ear4 9gs1ye while tho yellow 10 SUPPOSED to
II now, We remember that botl, Mira and sat-
IN thine by tho aid Of tho sa,no aunrht. which
. roilectod from thom to our eycs. wa m,'st no,.
Judo TINT these differences OF apparont color
re- due to different conditions ln tI,n bot]ien
or In thoir ulosploros-uro]1ahlv
MY IN tho latter. Tho spgetroscopo ia hero Al
.yA!uau!e w ala, u not onlY proves that tlolr