, 1876-03-22

supposltiou that both arc perfect eiroles, tho |
reHalt will differ slightly from tho calco.atlon' II
ths. outline OF lunar mountain nDs Of
tDoon moves, on an avorago, through about 90
milo por aocond; 20 that dopr6ason OF elevation
Of milo below or above tho avorARo surface
would invoyo - error ol nosr!y t"o sSeonas 70
tho Visible contour Of thc sum- hlmeeil. IL con
ttnuously changing. introducing another source
Of minute (deconds) error. .,
difficulty Of noting Tho o1aet instant of appatons
contact, tho aaloufstion Of tho beginning anu
ond OF solhr co1tpeo eannot 30 depehuou upon
70 within = fow seconds: With this provlao wo
Observatory. in North Latitude II degrees, 30
nlnutoe, saaoud, md West Longitude from
Greenwich, honrs, 60 minutes, 2o:b SECONDS
Ii 2h. Ann, 7s. P. m. for the beginning, and Al.
fti po1tton Of Chicago is lIttlo more than 8 mies
north, and about milo vcst. from tho Obeorvn-
tory Applying :.o corrections % nosod E1 Above.
" n th.s toI ths noghbqffhooa o. Tn ra
giyca seconds earlior, and ~ leoonas lAtor
or Tho oclipss should begin at 2h: 42n: IL. r.
u, aud end a. Al. 38n. 4os ?. m. That ia: 2n.
We nsye dwoft moro particularly upon tho
matter OF Hnuo contact because tho partial
eoiipse OF tho sun, however Interesting i mar
be to tbs casual obaorvar, ID Of vhluo 70 tho a.
tronomo1 only In q Mathematical Way: II inr-
| Hf6uG1 uU Qpotkut VFEoAsAAAt@ IVA otANJte-FS
"flanng" protuberances, na they hro called,
The C soaa as sas' a.dg Of go i. L 'esss sua
Saoe fsmsns Sneegeroa %, by y,ots1 .h0 - noon onv
part Of the wortd-betng annular along tho con.
tral line. This statement OF tho condittona Of
Tho problem may also. sorvo to dsabueo tho
minds Of eomo pooplo who fancy that evety g.
tronomlcal event can bo oyphorod out hnfoso-
baud. to tho hunlrodtt part Of = second Of time,
and that Ii tho ono does not precisely conform 10
| tho othor It Ia because OF an error IN tho cal
| onlRtion. Those people rtmlnd ono OF the fustin
| who had obtained possession OF a watch, aud,
proud Of bis tsmoptccc. pulled II out ono morn
Ing. coming to tho aadiblc conclusion: ~ elio
aun isn't up over that it'll In a minuto and hall
from tlis ol be l,to - Tho TINE ana ~ ia!si s
Off lunar eo!srso to Tho nearest hecond arc
employed In Almoat e1uRl ignorance Of tho con-
ljtion1 which limit tho value OF tho calculation.
cAuBE OF TIE AENuLAn pHAHE.
TIE earth and moon ewing around each other
at the arorago distance Of little less than 239,
900 mica, but owing to the eccentrcity of tho
orbit that distance ID Increased and diminta1ed
by about 10, 100 miles. and tho suna disturbing
1900 milea. The common contre Of gravity
Of tho two bodies hiao doaotbes m elltpse around
tho sun. tho distance varying 1,5io,ooo miles
each way from tho average Of 92,oso.ogo miies. Il ::
Compromising these two variations We md that
the distance of tho Garth from tho sun, oxpreaaod
! In termB of the moons RctuAl dlatRncos varies
botwceu 358, and 412 tho average being nearly
| 38Sk. THO actual Dimensions Of tho Two bodies
remaining tho same, thotr apparent magnitude
decreAses with an Incroaao In tho distance, and
vice vorBa- w
Tho average angular magnitude OF tho (fnll,
moon ig little less thau that Of tho sun. Whor
both Are at tloir average distance from rs, Il
|. Tho moon paes directly between ua and the attn
hor shadow rohchos very nearly ns far ~ thu
point Of the oartt's surface shloh IL thon noaz
osk to her, II the relative distance OF the hui
/ bo greater than 985L tho shadow is longer thai
, tho moons DISTANCE and tho eclipse b total I,
ali pnrts Of tho oarth'a surface which ar
nwent by tho shadow. II the rclativ
distance Of Gle sun ! bo less TIM,
= 85516, tho shndow docs not roach tn
i oart6, and tho sun appears to DO larger thai
Il the moon. That Ia tho case tn the present ~
Il stance; and 10 oil porBons who Natch tho eops
Il from any part OF the aur3ace which Is 1nomanta
"A rily III line with tho centIoe OF tho moon an
Il sun, tho former Will anreRr TO bo surrounded
the ring Of sunlight Which IL tho distinctive foa
n turo Of tho annular eclipse.
u Tho eclipse will DO wateliod from the Doal
! born Observatory, weather permitting prooabl
BY Prof. Proctor. In that event tho tncmbofs Q
the Astronomical Society will be tuyited to moe
him at tho Observatory on saturday afternoon
Of which duo notice will bc givon.
Al TIE NEXT.
n There will not bo Anothor important tcltpAo {
4 tho eun after that of na1t Saturday till July 2
q 1878. That eclipao will DO total but not a. Oh
81 oclipso only. Tho Hue OF totallty will Gro.
IL tho Pacific Isni1road not far from Fort Bridge
II | and nabB = few mllcs southwest from UenYt
q into the Gulf OF Mexico. It will probably
II watched by natrouomosa With equal interest .
: that Of lbG0, though tho path Of tho contr
= phase will DO much loaa faTotaoiy situated 4
Q observation than that OF Hi1 and hall yea