198

Astronomy.

peared in the Year 1682, whose •[]

* TT f -I*/-* 1 1 ^

A

is 75 Years and a half, and therefore

PI. LXI,Fig-. 2.

Offltl 1

of the Body at M, and is equal to the Ang'l e ? /i ;iBMT. Now this Angle or Parallax is c ° I J )t , s i°'diminishing, as the Phœnomewn at M approa c _ J>ufwards the Zenith at E,' where it entirely vanil^ s ’jti sincreases as it approaches the Horizon at G, ^ j sdgreatest of all, and is there called the Hori% in p ( gfthrallax, which in the .Moon amounts to a tvhoSas was Ihewn Annot. C XXXV.

17. It is here observable, that the Para!l a * oJl lv lSdepresses the Object, and therefore when theNorth Latitude it is diminished, but the South •v.‘ c ]]p t ' l sIs increased, with respect to us ; and so the .Limits are variable in every particular Latitude- ^ ( e<Solar Eclipse may in an absolute Manner be b e * ^sented by a Projection of the Earth’s Disk, 311 0 f ^Section of the dark and penumbra! Shadow g c 8 &"Moon, as they appear (or would appear) to a Tjoifftor at the Distance of the Moon in a Right E ,|tl

ing the Centres of the Sun and Earth. .

18. In order to this, we are to find the Dj 1 ^ Sbj*of the apparent Semidiameters of the Earth, ^ Ajdow, and Penumbra, at the Distance of the M 0 .^ c qPto the fi. st, viz. the Earth’s Semidiameter, ^ !

to the Moon’s horizontal Parallax, as we h aV f e£ C ;That of the dark Shadow is thus estimated : JStfB *■the Centre of the Moon, D B its Diameter, V ffbs'dark Shadow, and KAL the Penumbral CoN^let E F be the Diameter of the Penumbra at th q stand I G that of the dark Shadow, and draWC E ; then is the Angle C G B = B H.C +and soGCHxBGC-BHC; that is, ^ t „ tj?rent. Semidiameter of the dark Shadow is ec l u 0 { $Difference between the apparent Semidia®etet sMoon and Sun. (See Art. 2. and 5.)

19. In like Manner the Angle E C H 7 £ },c 1 ‘

D A C, that is, the apparent -Semidiametet 0 ^

nuntlra at the Earth is equal to the Sum o* . st

pY