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filling it so often with Light, and by having lasted as many Years as the World, may feem to have almost confumed all its Light; and fo if not quite wafted, yet must be greatly diminished, fince that is contrary to Experience: For in Anfwer thereto, befides, that no Body can be perfectly affured, that Light does not circulate like the Blood in Animals, and after having performed its Course, comes back to the Sun again; which Cartefius, probably to avoid this Objection, feems to have thought: I fay befides this, the Particles of Light may also be conceived to be fo very fmall, that notwithstanding they do fo far fill this whole Orb, that the Interftices or Spaces that are between, may remain entirely unobferved by us; yet being taken all together, they may not perhaps amount to the quantity of one Grain of Sand; for which Reafon there could be no Diminution perceived in the Body of the Sun in as many more Years or Ages.

Now as wonderful, and perhaps as incredible too as this may appear to many, it is nevertheless well known to the Mathematicians, that the great Space of which the Starry Heavens fhou'd be fuppofed the upper Superficies, might be filled in fuch manner with corporeal Particles, that no one Ray of Light, how fine and flender foever, if it had but a determinate Magnitude, could be able to pafs between the fame, and confequently the faid great Space would be abfolutely opaque. All which corporeal Particles, if they were joyned together, would nevertheless not only not make the quantity of one little Grain of Sand, but even not of the smallest Part thereof, provided its Magnitude were likewife determinate. See Dr. Keil's Introduction, p. 54, & 55.

SECT.

SECT. XXVIII. The Ufefulness of the Divergency of Light.

BUT if an Atheist fhould confider this continual and fwift Stream (as it really is) proceeding from the Sun, not only as it brings Light always with it, but likewise an actual Fire; he muft be forced to confefs, according to the Experiments of the Burning-Glaffes, that if this Light and Fire fhould defcend to us in fuch a close and compreffed Body as we find it is when the Rays of it are collected in the Focus of the faid Glaffes, the whole Globe of the Earth with every thing belonging to it, would foon be reduced to a more dreadful Glowing than Metals put into Fufion in a Furnace. Now it is fure enough, that this fiery Light is more hot and deftructive near the Sun, than in the aforefaid Focus; fo that in order to convert the Earth into a glowing Ocean, of which one can hardly think without trembling; nothing more is required, than that the Light fhould come down quite to us with its Rays, as compact and closely united to each other, as it really is near the Sun.

This being laid down, let him seriously weigh with himself, whether he can think it to come to pass without Wisdom and Direction, that there is fuch a Motion communicated to the Rays of Light, and fuch a Law prescribed to them, which they have ftrictly obeyed hitherto for fo many Ages, without once receding from 'em, tho' they themselves are entirely ignorant thereof, and whereby the Earth, and even the Univerfe itself have ftill been preferved from this allconfuming Fire. The Laws we mentioned to which Light is fubject, are, that as foon as it comes from the Sun, the Rays of it are fcatter'd

and

and divided from each other, and continually more and more fo, the farther they proceed in Right Lines. This the Learned exprefs by the term of the Divergency of the Rays.

Of this we have spoken before, when we treated of the business of Vifion, or Sight, and of Fire; and to avoid Repetitions, we fhould have paffed it by here, were it not that from this Divergency or Separation of the Rays of Light, there feem'd to refult a Proof, which is alone fufficient to cause an Infidel to fee with indifputable Clearnefs, that there is a God that governs this now fo beneficial and ufeful, but otherwise fo terrible, Substance of Light and Fire, and thereby preferves from unavoidable Destruction, every thing that has Life and Being upon the Earth.

SECT. XXIX. The Properties of the Divergency of Light.

WE fhall only add the following, to what has been faid before upon the fame Subject, to the end that those who are not verfed in Opticks and other parts of Mathematicks relating to Light, may have plainer Notions thereof: Let it be then fuppofed (Tab. XXI. Fig. 2.) that S is a Point in the Sun, from whence the Rays S a A, Sc E, Sc C, Sd D, SbB, &c. in their Progrefs from S to A, C, D, E, continually diverge or recede as they move from each other: Now there need not be much pains taken to fhew, that the fame Rays which at the diftance S B, fall upon the Plane Circle A E CD, when they are nearer to the Sun; and for Inftance, when they have proceeded no farther from it than to Sb, are all within the Circumference of a fmaller Circle a ecd; and confequently, that the Fire of which thefe Rays confift, or at leaft

which

which accompanies them, is fo much thicker, or preffed together in the little Circle a e ed, than in the great one A ECD, as this laft is bigger than the former; or to speak in the Language of the Mathematicians, the Heat which the little Circle a e c d undergoes, is fo much greater than that which the bigger Circle A ECD feels from the fame Rays, as the Square of the Distance of the great Circle, or of SB or SA, &c. is greater than the Square of the Distance of the little Circle, or of Sb or Sa: That is to fay, when S B is twice as great as Sb, the Heat at a ecd is twice two times, or four times greater than at AECD; and fo SB being 100, and Sbs, their Squares are 100 times 100, and five times 5, or 10,000 and 25; and confequently the Heat at aecd: Is to the Heat at A ECD: As 10,000: To 25, or as 400 to 1, which is likewife confirmed by Experience.

From whence it is then manifeft, that if one knows how much one Place is nearer to the Sun than another, one may likewife according to this Rule, make an exact Calculation how much more Heat is produced by the Rays of the Sun at one Place than at another upon occafion of their Distance; and generally that 'tis true, that by how much the nearer any thing is to the Sun, fo much the greater Heat it must undergo from the united and compacted Rays thereof; as alfo the farther it is from the Sun, the lefs will it feel of its Heat.

Now as this is known to be true by all Mathematicians, let an unhappy Atheift confider in his Retirement, whether he thinks it can be by Chance, that a glowing Sea of Fire above 100,000 times bigger than the whole Globe of the Earth, is about the Sun at S, the burning Rays whereof SB, SA, SE, SC, SD, &. come

down

down with fo unspeakable a Swiftnefs inceffantly, (and therefore in fuch a Number as is hardly to be conceived) upon the Earth at ADCE; and yet that this terrible Fire does not immediately, and in the moft difmal manner confume every thing upon it.

'Tis true indeed, that the Distance S B, which is between the Earth B and the Sun S, being of the Length of 12,000 Diameters of the Earth, may contribute fomething thereto; but yet this beautiful Globe is by no means preferved from the aforefaid terrible Destruction by this only. To underftand which, let it be fuppofed, that there comes down from the Point of the Sun S upon the Earth, the Rays Sa, Se, Sb, Sc, Sd, &c. without Diverging, or in parallel Lines, and clofely joyned together; or (to render the Notion thereof yet clearer) that the faid Rays being near the Sun at the Point B, are diverged and feparated from each other as they go, but proceeding farther lofe their Divergency; and defcending down by their Parallelifm or Equidiftance form the circular Column a e m k, it is plain, that all of 'em will fall upon the Circle k m, and there produce a Heat, which is fo much greater than that which would be perceived in the great Circle AE CD from the fame diverging Rays, as this laft Circle is bigger than the little one k m. This appears from the Burning-Glaffes, the Force of which does only confist herein, that the Rays are collected into a fmaller Compafs; fo that they give a clear proof of this Truth, that the Rays of the Sun being collected into a narrower Compass, even at fo great a Diftance from the Sun itfelf as is the Earth, are yet capable of producing a terrible Heat. From whence then it does follow certainly enough, that it is not fo much the Distance of the Sun, but the Diver

gency

.

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