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Show NoTE V. IO . · d . 1 1759 accordmg to sUN'S RAYS. . nd r682 having returne In t le year ' The comet of I 53 I' t6o7' a . T' f r I 70... there feems no reafon to doubt d. n · · the Philo f. ran · JOr ), h · Dr. Halley's pre Ic.llon m .f h . per periods. A!honomers ave m I t ill return a tcr t eir pro d 66 that all the ot ler come s w . f D H II that the comets of IS32, an I r g . r I. tl conjeClure o r. a ey, . d eneral acquiCiCC< m le '] . f tl e clements of their orbits, an were r t from the fimi antyo 1 . . 1 are one and the Iame co"m ae ' . 'l 1' . I78<9 As this comet IS l!ab e to its return to ItS pen lC !Urn In . I therefore induced to exre th lanets Jupiter and Saturn, Dr. Ma!ke yne be di!l:urbed ir, its aCce.n t from. the flln by e p ~ . f he year I 789 or the latter end ~ r . n the beg I nmng () t ' expected its return to Its pc~·~ le tum J • b ~ the 27th of April, I789, which pre-of the year q88, and certamly fot~e t~me e ore] LXXVI. b f !filled PhJI '1 ranf. Vo · h diClion has not een u · · d f: · their perihelion very ncar t e r ll na!fes of matter, an pa s 111 As the comets are lma t • fhort fpacc of time, their number . 'fiblc to us on thcle accounts m a f fun, and become tnVJ I . I ']! b bly increafe with the improvement o our b (, tamed anc WI pro l d I has not yet een a cer '. bl f 2 comets whofe orbits are alrea y ca cu- M Bode has given a ta e o 7 ' . . d n. telefcopes. · . . I, b't and only twelve wtthout tt; an mo1L f I r 6 pafs wtthtn the cart 1 s or I , latcd ; o t 1ete bo he orbt. ts o f V enus a nd Mercury ' or nearly midwa.y be. tween of them appear etween t d f the planes of their orbits, being wclmed to {i d th from whence, an rom f: r· bl ttJe un an ear ; . 11 ITibl angles they are believed to be le s ta e to f I h dotherplanets Ina po I e ' h t. hat o t le c· ahr t an· · re each ot I1 cr. M · B0 de afterwards inquires into the nearcfl: approac . fi d mterfere Wit 'or InJU . ke towards the earth's orbtt. He n s ffibl r I of the known comets to ma ·r it is po I e lOT eac 1 . h' d' fiance equal to two or three times the dt - l h f them can come wtt m a J h fl.. ld that on y t ree o . d 1 dds the great improbability, tha~ the cart wou f h from Jt. an t len a I b tance o t e moon . t ·o f . . 1 . n. t when a comet which may 1ave ecn ItS orbit at t le lllllan ' . be in that dangerous P0111 . d; !l: . t Hiftoire de I' Academ. Royal. Berlm. abfent fome centuries, pa!fes fo rapt y pa I • I 792· NOTE V.-S UN'S RAYS. Or give the fun's pblogi)lic orb to roll. CANTO I. I. I]6. . b hlo i!l:on is not concerning the exi!l:ence of THE difpute a~no~~ pl~,\~f~~~=;~ah~~:;the~e be one or more inflammable principles. an inflammable pnncip e, ~1 r '111 l . I ded the whole chemical world, believed in The difciples ofhlSta~~· W~lchlltibodai.tees r;~i~~ would flame or calcine. The difciples of b 'd" ·ty ofp oguton tn a . f h 1 t e 1 '_{nj u h ge to a plura \t' ty o f Ph i og·unt ons under the vanous names o c arc. oa · ' Lavm Ier pay oma ' Jl ' t 'th pure air and thence compofe an aCid, IS 1 tals &c Whatever w1 um e WI ' fulp mr, m. e h' ' · . . ous theory to b e a d'Irure ren t k'Ind of phlogiflic or inflammable body. e!l:ecmed 111 t .Is tn~em ins a doubt whether thefe inflammable bodies, as metals, Afutl pth~ue rf,a mc hea rtcimoae ! , t&lecr·e ~:Iyn~ot be compounded of the fame phlogi!l:on along with forne ·Non: VI. CENTRAL FIRES. lt other material yet llndifcovcred, and thus an unity of phlogi!l:on exi!l:, as in the theory of Stahl , though very differently applied in the explication of chemical phenomena . Sot~lc mod ·rn philofophcrs an.: of opinion, th:lt the fun is the great fountain from which the earth and other planets derive all the phlogiflon which they po!fefs; and that this IS formed by the combination of the folar rays with all opakc bodies, but particularly with the leaves of vegetables, which they fuppofe to be organs adapted to abforb them. And that as animals rcc ive their nouri!hmcnt from vegetables they alfo obtain in a fecondary manner their phlogill:on from the fun. And laflly as great mafles of the mineral kingdom, which have bl:cn found in the thin emf!: or the earth which human labour has penetrated, have evidently been formed from the recremcn ts of animal and vegetable bodies, thefe alfo are fuppoled thus to have derived their phlogiflon from the fun. Another opinion concerning the fun's rays is, that they arc not luminous till they arrive at our atmofphere; and that there uniting with fome part of the air they produce combu!l:ion, and light is emitted, and that an etherial acid, yet undifcovcred, is formed from this combunion. The more probable opinion is, perhaps, that the fun is a phlogi!l:ic mafs of matter, whofe furface is in a !l:ate of combullion, which like other burning bodies emits light with immenfe velocity in all direCtions; that thefe rays of light act upon all opake bodies, and combining with them either difplace or produce their elementary heat, and bccome chemically combined with the phlogifl:ic part of them; for light is given out when phlogifiic bodies unite with the oxygenous principle of the air, as in combuil:ion, or in the redu8:ion of metallic calxes; thus in prefenting to the flame of a candle a letterwafer, (if it be coloured with red-lead,) at the time the red-lead becomes a metallic drop, a flalh of light is perceived. Dr. Alexander Wilfon very ingenioully endeavours to prove that the fun is only in a fl:ate of combu!l:ion on it fiJrfacc, and that the dark fpots feen on the di!k are excavations or caverns through the luminous cru!l:, fome of which are 4ooo miles in diameter. Phil. Tranf. 1 774· Of this I i11all have occafton to fpeak agaiu. NOTE Vl.-CENTRAL FIRES. Rou11d her fli~l centre tread the burningjoil, And watch the billowy Lavas, as they boil. CANTO I. I. I]9· M. DE MAIRAN iu a paper publilhed in the Hi!l:oire de !'Academic de Sciences, 1765, has endeavoured to {hew that the earth receives but a frnalJ part of the heat which it po!fe!fes, from the fun's rays, but is principally heated by fires within itfelf. He thinks the fun is the caufe of the viciffitndes of our fea{( ns of fum mer and winter by a ve ry fmall quantity of heat in addition to that already refiding in the earth, which by emanations from the centre to the circumference renders the furface habitable, and without Bz |
