U N 



Sir ir.iac Newton HluH made it probable, thai clie great 



comet in th'jyear 1680, in its perihelion, went f) near 



the Sun, as that it acquired a heat, which would not 



entirely go off in 50,00c years ; whence we may guefs, 



that if the Sun and. fixed flars be only cclieclions of 



denfe and folld matter, like the planets, but heated 



to a very intenfe degree, they may be many millions 



of years without loling any confiderablc part of their 

 heat. 



Accordino; to Cafllni, the Sun's difuance from the earth 

 13 172,800,000 Englifh miles. 



As for the annual motion of the Sun round the earth, 

 it is eafily fhewn by aflronomers, that the annual mo- 

 tion of the earth will occafion fuch an appearance. 

 A fpetftator in the San would fee the earth niove from 

 \ve(t to eaft, for the fame reafon that we fee the Sun 

 move from eaft to w^efl, and all the ph£enon"iena re- 

 fulting from this annual motion, in which foever of 

 the bocUes it be, will appear the fame from either. 

 As to the nature, properties, and figure of the Sun, 



&c. 



1. As the folar fpots are found fometimes to flay three 



days longer behind the Sun than they fpend in pafTmg 

 over the hemifphere vifible to us, we eafily deduce 

 that they do not adhere to the furface of the Sun, but 

 are at fome diftance therefrom. 



2. As the fpots frequently rife and vanifh even in the 

 midiL of the Sun's difk, and undergo feveral changes, 

 both v/ith regard to bulk, figure, and d-enlity, it fol- 

 lows, that they frequently rifcj de novo, about the Sun, 

 and are again diffipated. 



3. Hence it fliould follow, that they are formed out 

 of the exhalations of the Sun, and are no other than 

 folar clouds. 



4. Since then exhalations proceeding from the Sun 

 rife above him, and flop at a certain altitude, it is 

 evident there is fome fluid encompafling the Sun to 

 urge the exhalations to rife, and this fluid muft be 

 deafer at bottom, and rarer at top, like our atmo- 



fphere. 



5, Since the fpots frequently difTolve and difappear 



• ^ in the middle of the Sun's difk, the matter of the fpots, 



,that is, the folar exhalations, fall back ao-ain to the 



Sun; whence it follows, that there mufl arife vari- 



i 



ous alterations in the Sun's atmofphereV anii'tlie'Sun 

 imielr. . . . v -; - 



6. Since the revolution of the fpots round the Sun is 

 found very regular, and likewife very near the Sun, it 

 follows, that they do not revolve round the Sun, but 

 that the Sun, together with his atmofphere, wherein 

 the macula: are, move round their corhmbh" axis in 

 an interval of about twenty-feven days -, and hence it 

 is, that the fpots near the limb, being viewed ob- 



^' -_■ 



^\ I • 



'■ lic^uely," appear narrow an^ long. - 



-lb?' S^^*^^ ^^^ S^^^j ^" 5y?^y Ji^^^M^"> appears like a 

 "'circular difk, its figufe,"'as to' ferife:^m uft.be Tp'he- 



rical, though it is really fpheroidical. ..^r;--,;"'",^ .,:' . 



, 8. That the fubflance of the Sun is' fire^ is'thus 



'.proved: the Sun fhines, and his rays, coUedled by 



concave mirrors/^ofl^corivex reiifes, burn, corifume, 

 ' .and melt the inoft folid bodies, or elfe convert them 





into afhes orglafs*;':-" 



^> - 





■JZ-3 -• 



f « 



'»■■ 



.--<.-^ - ■* 



,, .'yV'herefore,'''as'the folar rays are diminifhed by their 

 r divergency in a duplicate ratio of the diflances reci- 

 ;■' procally taken, it is evident that their force and ef- 

 .. led is the fame when collefted by a burning lens or 

 ' mirror, as if we were at fuch a diflance from the Sun 

 ... where they were equally denfe. The Sun's rays there- 

 : fore, 'in the neighbourhood of the Sun, produce the 

 ,. iame efJccls as might be expefted from the mofl 



ment fire 5,' confequently, the Sun is of a fiery 

 fubflance. '' '" ^ . 



Hence it follows, that its furface is every where fluid, 

 that being the condition of flame. 



Indeed it js not abfolutely determined, whether the 

 ^'^io^e_t)Ocly of the Sun be fluid, as fome think, or 

 folid, as others i but as there are no other niarks, 

 whereby to diflinguifh fire fromother bodies, but light, 

 hear, a power' of burning, cpnfuming, melting, cal- 

 cining, and vitrifying, we do not fee whaVfhould hin- 



N 



dcr, bvit tliat the Sun may be a globe of fire hkc 

 ours, invefted w^ith flame. 



9. Since the maculrt are formed out of the folar ex- 

 halations, it appeal's, that the Sun is not pure hrc, 

 but that there arc heterogeneous particles ir.ixed 

 with ir. 



Some make t!ie mean difunce of the Sun 



luntr 



eardi 



7490 

 others 12,000. 



diam 



from tlic 



'*rf> 



eters of the earth, 



others 10,000, 



The Sun, according to that excellent chemifl:, the 

 younger Lcmery, fcems to be no other than a hu 





mais, or colleftion of the matter of lire or li^^hr 

 though fo placed as to difable it to acT; on bodies here 

 on earth, otherwife than by one of thefe tw^o ways : 

 firft, by emanations or emiflions of his own fubftance 

 tranfmittcd liither ; but this hypothefls being fubieft 

 to great difficulties, and not fufficiently anfwerint^ to 

 certain pharnomena, recourfe is had to another, which 

 fuppofes trains of iire or light, difpofed in all the in- 



expanfe of air and aether be- 

 tween the Sun and us ^ and that thefe trains are 



terftices of the grand 



made 



to a6l on terreflrial bodies, by their being vigoroufly 

 driven or impelled toward fuch bodies, by the imme- 

 diate aftion of the Sun thereon. 



Thefe trains, in effeft, may be efleemed as a fort of 

 little Suns prolonged, but always depending on the 

 great Sun, as the fource of their motion and aftion 

 on bodies ; it is thofe that form the rays of light ; 

 they do not, in point of matter, ditfer from the fub- 

 flance of the Sun himfelf, but only in this, that the 

 fame thing is more copious in one cafe than the other. 

 In the Sun we may fuppofe the matter of light more 

 abundant than in the focus of our largefl burnino-- 



Thus from the vehement aftion of the rays 

 of the Sun collefted in fuch glafs, we learn what ufe 

 the air, interpofed between the rays of light, is 

 of in tempering their a6lion, and rendering it more 

 fupportable, fihce, without fuch medium, inflead of 

 warming and illuminating, it would blind and burn us. 

 So that the air may be confidered as having fomewhat 

 of the fame efFeft, with refpeS: to the rays of light 

 upon us, that the water in a balneum maria^ has, 

 Mem. de I'Acad. ann. 171:?. ' 



-Omitting to enter into a particular difcufTion about 

 'the matter of the Sun, and whether it be fire, to us 



glafTes, 





->-*' 



It. appears very extraordinary, that the Sun, after a 

 continual emiffion of the corpufcles of fire upwards of 

 5 coo years, Ihould not be yet exhaufled. . . 

 Whilll the Sun is above the horizon, he impels all the 

 rays, before vague and fluctuating,' toward a focus, 



;and fuch impulfion or determination is always in right, 

 ■■'lines; fo that all our light, heat, and colour, is the 



, effeft of a rectilinear motion. 



';^Suppofe, for inftance, a fire in a dark place, and 

 a thermometer placed at a certain diftance therefrom, 

 with an iron plate between thsm ; in this cafe, the 

 thermometer will not be aflefted by fire, by reafon 

 that the reftilinear paffage of the heat is flopped. 

 Nor need it be added, that under the like circumftances 

 no light, colour, &C. are perceivable, fo that none 

 of thefe a6t but In right lines. 



If the re were no Sun, nor any body to fupply it5 place, 

 there would be no heat, i.e. the fire would not be 

 determiried in right lines, fo that the Sun is the fa- 

 ther of all heat, or forrie other tody that a6ts in the 

 fame manner as the Sun, for the Sun does not make 

 heat, but only the difference between the heat of the 

 day and the night. 



Dr. Halleyobferves, That the Sun, radiating on the 

 earth in the morning, has but little effeft, but that, 

 when raifed to the meridian, he a£ts with all his force. 

 Now this is owing to the atmofphere, which, being 

 replete with an infinite number of corpufcles, refletSs 

 more of the Sun's rays to the earth, when they fall 

 perpendicularly, than would otherwife arrive there ; 

 for wheieas falling obliquely, they would be refiefted, 

 and thus be thrown off, and difperfed into other parts, 

 now that their incidence is perpendicular, they will 



pafs dircftly through. 



It-- 



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