Astronomy, j gg

|^M- a ^ ear in 1758. By this Piece ofc stnery is shewn the unequal Motion of

a Comet

n

^ovA e j mi 1 iameter °f the M° on and Sun.' (Sec Art. 7.)l he ^ semidiameters of the Sun and Moon, and alsofor^ 0011 ’? horizontal Parallax, are already calculated^6 t Va tious Distances of the Sun and Moon fromcities f’ and for hsst, mean, and greatest Eccentri-2 0 0 the Lunar Orbit, in the Astronomical Tables.tile a * therefore let A E represent a small Portion ofof th e n T^ Orbit, and E H the visible Path of the Centreto tlJ p nar shadows, which will exactly correspondthe g position of the Moon’s Orbit with respect tointe r c Nf's * n tbe Heavens ; and therefore the Point ofl he /"'on g will be the Node, and the Angle H 8 EPlitjg n 2 l e of Inclination of the Lunar Orbit to the2j P^the Ecliptic, which is about 5 Degrees.

^a,'tb s* ence is /E P Q_S represent the Disk of the^ Ve ta] p Cort ‘‘ ,1 S so the Orthographic Projection) in theI stast c PHces txi, B, C, D, whose Semidianreter isHo r : ec l Ua l to the Number of Minutes in the Moon’sstfn P nta l Parallax at the Time of the Eclipse; and^ es e P at h of the Shadows in the Points q , R, N, G,to th '/‘/e a small Circle whose Semidiameter is equala nd .“ifference between the Semidiameters of the Sun^°0n’ iO ° ni tFat sbAl be the circular Section of the(by , s (lark Shadow at the Distance of the Earth:Cibg J &0 Lastly^ if on the fame Centre we de-’he e a Hrger Circle, whole Semidiameter is equal tothat n/,os t be Semidiameters of the Sun and Moon,.E represent the Section of the Penumbral Sha-Are a 5 > b 7 Art. 19. ) and is here sliewn by the dotted

he a( .' t ,^- ere then it is evident, if the Moon, when New,^ad 0 e distance K G from the Node, the Penumbralthere c "ot fall near the Earth's Disk, and so

•b*sta anil °t possibly happen any Eclipse. If the Moon’sPeny 111 / ^ r0in the Node be equal to Q N, then theij Ue J t*l Shadow will just touch the Disk, and conic-P & C the Ecliptic Limit \ which may be found0 4 «a

PI. LXLF ‘g- 3-