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Show SU SU SU and a lower of cegtrai one, in all refpects vehement Action of the Rays of the Syn cola alike, and the fame with each other, accord- le&ted in fuch Glafs, we learn what Ute the Air interpofed between the Rays of Light js ing to the Dogma of Trifmegifius. On the fecond View, the centra} and fubterraneousFire is not original and elementary, but determined and collected Fire ; fuch as we have it on various Occafions about the Surface. Tt may be added, that the denying Vent or Paffage to this fubterraneous Fire, appears to be the Caufe of Earthquakes ; thofe ufuaily arifing upon a Vulcano’s appearing to be ftopt up, or ceafing its Eructations, and going off again uponits opening, or burning afrefh. Fire may becollected in two manners: Firft, by a Luminary determining its Rays into a Parallelifm ; fecondly, by Attrition. Firft, Fire is collected when by any Means a Quantity thereof is driven into a leffler Compafs ; it being Part of the Charaéter of Fire, that it fpreads itfelf equally ; fo that if left to itfelf, it would be found no more here than there, and confequently would be infenfible every where ; bur if by any Caufe it be di- rected toward anycertain Part, then it difcovers itfelf: And fuch a Caufé is the Sun, which around pufcles Lines, Places. revolving with prodigious Velocity his Axis, directs the impervious Corof Fire, every Way in parallel Right and determines them toward certain of, in tempering their Aion, and rendering it more fupportable ; fince without fach Medium, inftead of warming and illuminatin & it would blind and burnus, So that the Air may be confider’d as havin fomewhat of the fame Effe&, with refpea a the Rays of Light falling upon us, that the Water in a Balneum Marie has, Mem, de i P Acad. Ann. 1713. Omitting to enter into a particular Dit cuffion about the Matter of the Sun, and whether it be Fire, to us it appears veryextraordinary, that the Suv, after a continual Emiffion of the Corpufcles of Fire upwards of so000 Years, yet Should not be yet ex4 haufted. The Sun and Stars, according to Sir zac Newton’s Conjecture, are no other than great Earths vehemently heated: For large Bodies he obferves, pnalerve their Heat the longeft, their Parts heating one another ; and why may not great, denfe, and fixed Bodies, when heated beyond a certain Degree, emit Light fo copioufly, as by the Emiffion and Re-adtion thereof, and the Reflection and Refraction of the Rays within the Pores, to growftill hot- ter, “till they arrive at fuch a Period of Heat asis that of the Sun ? The Sun therefore does not produce or emit Their Parts may be further preferved from Fire, but only puts it in Motion in Right Lines, and thus collects it. And hence it is that we perceive Fire fo long as the Sun is So the Dutch, who wintered in that unhap- Effect of a rectilinear Motion. py Region, expected no lefs, and that in the Month of July the Sea fhould be thaw’d, and they left at Liberty to purfue their Voyages Diftance therefrom, with an Iron Plate be- but were miftaken. This gave my Lord Batween them; in this Cafe the Thermometer con Occafion to obferve, that the Sun’s direc will not be affected by the Fire, by reafon Rays have no fenfible Effe€t, not even on a that the rectilinear Paflage of the Heat is ftop- level Country; nor yet the reflected Rays, ped. Norneed it be added, that under the unlefs the Line of Reflection be near that of like Circumftances, no Light, Colour, &c. is Incidence, i.e. unlefs the Angle intercepted perceivable; fo that none of thefe aét but in between them be very fmall; fo that they Right Lines. may, as it were, ftrengthen and increafe the If there were no Sv#, nor any Body to fup- Weight of the incumbent Atmofphere, in this latter Cafe, keeping down the Vapours, and hindering the Ebullition, *till it has conceiv’d So alfo, a Mixture of Tin and Lead, put on a red-hotIron, in vacuo, emits a Fume and Flame ; but the fame Mixture in the open Air, by reafonof the incumbent Atmofphere, does not emit the leaft fenfible Flame. Ji. It is, fays and /Ether between the Suz and us, and that he, muchfafer to fay, that the Sun has the thefe Trains are made to a& on terreftrial Bo- Power of determining Fire, than that it furdies, by their being vigoronfly driven or im- nifhes it. ‘The Cafe may be the fame, 4s in pell’d toward fuch Bodies, by the immediate M. Villette’s Mirror, which, when exposto Aétion of the Suz thereon. the naked Sun, produces fuch amazing Effects, Thefe Trains, in effect, may be efteem’d and yet has no Effect at all, if the Su» be as a Sort of little Suws prolonged, but always covered from it, by the Interpofition of 2 Cloud, or the like: The Mirror may appes the Caufe of Burning, but it is only an In- ftrument neceflary thereto ; and the Swma) be no more. If now the Su impel the Matter of the Fire in Right Lines, we call it Light, which Light is not any fiery Corpufcles in the Sun itlclt, but the vague Fire above-mentioned, put in a new Determination by the Suv, and collected into fome one Place. Hence Now, the more per- The Excefs of Heat which wefeel by Day, but the Matter of Fire drawn in parallel is not owing to the Matter of the Fire, but Lines, without which Motion there would no to the Sum. For as to the Quantity of Fire; fuch thing ever be feen. it has been obferv’d, *tis the fame by Night If now the Particles of Fire,, before moveas by Day,. and that is the Determination in ing in a parallel Direétion, become determin’d Thus we fee, that warm Water in an ex- the hotteft Water, open to the Air; the Effect of each other. ply its Place, there would beno Heat, i. ¢. the pendicularly the Rays fall, the fmcler is the Fire would not be determined in Right Lines: Angle: Hence, in Nova Zembla, where they So that the Suz isthe Father of all Heat; or fall extremely obliquely, the Rays by Reflecfome other Body that aéts in the fame Manner tion are fever’d, and that Effect thus render’d asthe Sum: For the Sum does not make Heat, infenfible. but only the Difference between the Heat of Dr. Boerhaave alfo adds: After the fame the Day and the Night. Manner arife Colours, which are nothing elfe forth his Hand, that it fhould be prefs’d, as with a huge Weight, both upward and downward, as if pinch’d in a Prefs, and yet there haufted Receiver, fhall boil as vehementlyas he muft tranfmit us more Fire in Waner than an Summer, As to this, Bacon de forma calida fays, It Suppofe, for Inftance, a Fire in a dark Place, and a Thermometerplaced at a certain mofpheres incumbent on them, and ftrongly fuppofes Trains of Fire or Light, difpos’d in Optic. all the Interftices of the grand Expanfe of Air But to return to Dr. Boerhaave. depending on the great Su, as the Source of their Motion and Aétion on Bodies; ’tis thofe that form the Rays of Light ; they do not, in point of Matter, differ from the Sub{tance of the Sum himfelf ; but only in this, that the fame thing is more copious in one Cafe than the other. An the Sux we may fuppofe the Matter of Light more abundant than in the Focus of our largeft Burning-glaffes. Thus from the that all our Light, Heat, and Colouris the point of Heat. Thus no body wouldimagine, in ftretching on Earth, otherwife than by one of thefe two its utmoft Degree of Heat. Ways: Firft, by Emanations or Emiffions of his own Subftance tranfmitted hither ; but this Hypothefis being fubje&t to great Difficulties, and not fufficiently anfwering to certain Phenomena, Recourfe is had to another, which has often been wondredat, why in Nove Zembla the Sun fhould never ‘have Power to melt Ice; notwithftanding that, for the Space of fome Weeks, his Brightnefs is not lef con{picuous than with us. parallel Lines, that makes the Difference in above the Horizon ; and uponhis fetting, lofe compreffing them, and condenfing the Vapours it again ; by reafon, as his AGtion ceafes, the and Exhalations arifing from them. Fire again {preads itfelf all around. The Sun, according to that excellent Chymift, the young Lemery, feems to be no other than a huge Mafs, or Collection of the Matter of Fire or Light, though placed at fuch a Diftance as to difable it to a& on Bodies here Hence arifes Heat. For all Heat depends on Fire; nor ts it felt, unlefs increafed in proportion to our Senfes, i.e. fo as to be capable ofaffecting our Organs. While the Suu is above the Horizon he impells all the Rays, before vague and fluctuating toward a Focus;, and fuch Impulfion or Determination is always in Right Lines; fo fuming away, not onlyby their Fixity, bat by the vaft Weight and Denfity of their At- SU anew in Lines that converge, the Effect of the Fire muft of Neceffity be heightened, by reafon a larger Quantity of Fire is, by fuch Means, colleéted into one Place. Andwere it not that by fuch Increafe of Quantity its Particles havea greater Attrition, is no Difpute as to the Fact; and the only the Forces of Fire would be proporticnable Reafon why he is not fenfible ofit, is, that to the Spaces it poffefs’d. the Preffure is equal every Way. But in bringing the Particles fo near, ’tis So it is with Fire, which, when equally impoffible but they mutt {trike on eachother5 moved every Way, does not give any fenfible Heat; but when the Swn fhines, he moves or directs it in Right Lines, and thusrendersits Heat perceivable. As to this, another Author adds; ’Tis not very difficult ta conceive how Fire fhould be- come fenfible, Sight, either to the Feeling or the by being thus determined in Right ines. By fuch Determination the vague, fluctuating Corpufcles are form’d into Rays, and a Train of them driven upon the Organ in a conftant Succeffion. Hence each fubfequent one feconding the Effort of the preceding one, the Impreffion by fuch a Series of Augmentations at length is fel. Thus the Air, with which we are every Way furrounded, if left at Liberty is not perceived; but if its Particles be driven ed in a Stream, whether by a Pair Hows, or any other Caufe that excites a Wind, the Impreffion it makes will be fenfible. Dr. Boerbaave adds; It may be doubted therefore, whether the Suwa, for all his Spots, be a hot Body; fince, if he were really fo, and hence, the nearer they approach, the greater and quicker the Attrition; andabrisk Attrition does collect Fire of itfelf. If then the Quantity of Fire in any Place be increafed, e.g. fix-fold, the Attrition will of confequence be augmented proportionably thereunto. Some maintain, that Fire aéts with more Force as the Refiftance of the Mediumis lefs 5 but the contrary is true; for Fire would be incapable of warming, unlefs either reflected or collected. The Heat wouldbe never the greater for the Sun’s aéting on theFire, unlefs in its Progrefs it were either refraéted or reflected, and by that Means determined to one Place more than to another. And hence it is, that the Cold, ceteris paribus, is always greateft in ftill Weather; and that in the Severity of Winter, and particularly frofty Weather, the Heavens are clear. Thus alfo the Tops of the talleft Mountains, where the Refiection and Refraétion are lefs confiderable, by reafon of the want of Clouds, are eternally cover’d with Snow; 78 as |
