A s T R O N O M Y.

^Uable

ion over a

graduated silyer’d

C‘

^rcl e : The Whole being .a just Represen-l °tt of the present T heory of those prodi-

Sio Us

and \Vonderful P'hœnomena of the l'la-

1 Ctar y System (CXLIV).

3 s| a st^^) I. I shall hers present the Reader withCompendium of the Newtonian C’ometo-Y as the Limits of this Work will permit, or,fsa ac jy’ as he may have an Inclination to read. Sirh[j: p as made the Doctrine or Jjlronomy of Comets thel>e ol his immortal Principia , and declares it toIbpliy die most difficult and intricate Part of Philo-

^ A o

^itn ■ v-omit is a Sort of Planet revolving about theC ° ll ^q ,1 . a ’ Ver F eccentric Orbit or Ellipsis, and whichitsQ^.y approaches very near tile Sun in one Partk in s °it, and recedes to a very remote Distance from^titz^Other. Hence stis evident, they must undergothat t(J e • e g rees of Heat and Cold. Hence it appears^odie s e C°niets are solid, .compact, fixed, and durableS > and not a Vapour or Exhalation of the Earth,1'it'A •‘Janets, as has been usually supposed ; becausejested 6re Cmh, it must inevitably be dissipated and dis—We q 111 Passing so near the Sun: For the Distance ofSS, 00 ^ of 1680 in Perihelio was so small that it con -degree of Heat above 200 times greater thani3 . Y e d-hot Iron.

l^ip, 1 et are they not so fixed, but that they emit a fine,w yet p Cl ^ Vapour ; which at first, while the Comet• r,1 i of^ reat WaY from the Sun, surrounds the Body in,'fibj e an Atmosphere, and begins to render the CometAj>o q ’r A?.the Cqmet approaches nearer the Sun, thisEights be S lns to ascend from the Head or Nucleus , toug S re ater and greater, as the Comet gets nearert^Cighf 61 to the Sun, and makes those amazing Streamsj^CfA 6 uluall y ttall their Tails. All which is easy•' lvc h'oni a View of the Figure,

4, These

203