An introduction to astronomy: designed as a text-book for the use of students in college. By Denison Olmsted ...

cqual to thle relative 1otion, and A::: te latitude ill opposition,
])D.:. tin lhatitude 011e hour afterward; joill dt and prodllco
tile lite d/( both ways, and it w\ill rep)resent the mloon's relativo
orbit. I)ratw 1Bb at right angles to C0), and it will be tle lati1ig. 6t.
A.... JAA
tulde an ollur before opposition. At tlhe time of t;.he cclipsc,
the apparent distance of tle cenlter of tile shadow flom tlhe
1lmoonl is very small; colsequntly, C), cd, ])d, &c., may )bo
_re Tgarded as straigiht lines. Du)\ring thie S11o't illterval 1)Cetwee
the lbcgillning ald end of anl etlipse, the motion of tlhe sll, alnd
consequently tlhat of tile center of tle shladow, may likoewiS
1e regarded as uniform.'
25'19. ile va-rious particulanrs tihat enter into tile calculationl
of an eclipse are ea1led its A.!'lem-ents; and as our0 object. is
here merely to pl;tfainti l t aethttd of calculalting- an c'lip)S of
tile moon (refeorrilng to tlhe &Sptimei t folr tile actual computation), we lmlay take tle! clenctents at their lmean valtue. 1'1111
we will conlSiCder Cd as inclined to CI) 5 9', tlie 1oo'01s }torizontal paarallax as 58', its semni-diameter as 16.', anid tlhat of them
earth's slhadlow as 42'. T'lle lite Am, }p)crpmellicular to ed, gives
tlie point ift for the place of tlhe moonl at the middle of tlte
eclipsC, for this litlne bisects the chlord, whliel rl)resents the
path of tlle 100oon through tile shadow; and wT, perpendicu]lar to 0D), gives A't fori the tilme of thle omiddle of tile celilpse
befotro opposition, tile Iunlembcr of mIintes before o)positioll
b)eing thle samle part of anl lour tihat.AM- is of AB.".l'From
tlhe center A, wvith a radius equal to thlat of the earth's shadow
(4W'), describe the semlicirle T1"l, anld it will roplcstlnt tlho
*'l'he itluationl of thoe moon when at m is called orbit oeposition; anld he1r Aitation when at a, (dipltic otpqositiont