all that Auguftus hath faid concerning it; and is yet an additional argument to that drawn from the equality of the period. Thus it is not improbable but this comet may have four times vifited us, at intervals of about 575 years;, whence the tranfverfe diameter of its elliptic orbit will be found 3575x575 times greater than the annual orbit; or 138 times greater than the mean distance of the fun. One thing more: Perhaps it may not be improper or unpleasant to advertise the astronomical reader, that fome of these comets have their nodes fo very near the annual orbit of the earth, that if it fhall fo happen, that the earth be found in the parts of her orbit next the node of fuch a comet, whilft the comet paffes by; as the apparent motion of the comet will be incredibly fwift, fo its parallax will become very fenfible. Now, the comet of 1472 had a parallax above twenty times greater than the fun's. And if the comet of 1618 had come down about the middle of March to his defcending node, or if that of 1684 had arrived a little fooner at its afcending node, they would have been yet much nearer the earth, and confequently have had more notable parallaxes. But hitherto none has threatened the earth with a nearer appulfe than that of 1680. For by calculation I find, that, November 11 d. 1 h. 6 m. p. m. the comet was not above the femidiameter of the fun to the northward of the way of the earth; at which time, had the earth been there, the comet would have had a parallax equal to that of the moon, as I take it. This is fpoken to aftronomers; but what might be the confequences of fo near an appulfe, or of a contact, or laftly, of a fhock of all the celestial bodies, (which is by no means impoffible to come to pafs), I leave to be difcuffed by the ftudious of phyfical matters.'

Dr Halley, in the laft edition of his Synopfis, printed with his aftronomical tables, retains most of what I have recited above, and adds what follows.

however excentric, inftead of the parabolic orbit of the comet in 1682, as inferted in my lift of comets, I undertook fo to adapt the pofition of an elliptic one given in magnitude and fpecies, with the fun in its focus, to the plane of the ecliptic, and the earth moving therein, as to reprefent the feveral exact obfervations which Mr Flamfteed made of this comet at Greenwich, thereby fubmitting my theory to the most rigid examination.

"Now, it is manifeft, that this comet completes two periods in 151 years very nearly, and those alternately longer and fhorter, to wit, of 76 and 75 years. Taking therefore 75 years for a mean period, (by prop. 15. of book 1. of Sir Ifaac Newton's Principles), the greater femi-axe of its orbit will be to the fun's mean distance from the earth, as 17,8635 to I; and the perihelial diftance having been by obfervation found to be 0,5825 of fuch parts, the excentricity of the or bit comes out 17,2810, whence the lef fer femi-axe 4,5246. The plane of this. ellipfe I find to be inclined to the plane of the ecliptic in an angle of 17 d. 42 m. and that its afcending node was in 20 d. 48 m. and the retrograde comets. perihelion in this plane, 1 d. 36 m. or 109 d. 12 m. after the afcending node; and that the mean time of the perihelion was September 4 d. 21 h. 22 m.

its mean diurnal motion being 75,5 of the fun's mean diurnal motion, or 47feconds very nearly."

And further, "Kepler's obfervations,. in his book of comets, printed at Aufburg in 1619, do evidently prove, that the comet of 1607 and that of 1682, were one and the fame; for both were retrograde, as was the fpecies of the orbit in both, with fcarcely a greater difference in the places of their perihelion and nodes, than we find in thofe of the planets after an interval of fo many years.

66

Though fome may perhaps object, that the difference of the inclinations and periods is much greater than has been obferved in revolutions of the fame. planet; fince one period exceeds the other by a whole year, and the inclina.. 3 Y 2

tion

tion of the comet of 1682 is no less than 22 deg. more than that of 1607: yet I would refer the reader's confideration to what I have faid at the end of my tables of Saturn, namely, that one period of that planet has been fometimes found to be full 13 days longer than another, occafioned by the force of gravity tending towards the centre of Jupiter; and cafes may happen, wherein, on the other hand, his period may be accelerated by a much greater quantity. How much more liable then is this comet to fuch fort of errors, which arifes almost four times as high at Saturn, and whofe velocity being increafed by no less than a 120th part, might have its elliptic trajectory altered to a parabolical one?

"Now, in the fummer of the year 1681, the comet which appeared the year following in its defcent towards the fun, was fo near Jupiter, and kept fo for fome months, that during that whole time it was urged towards the centre of that planet with about one fiftieth part of the whole force with which it was urged towards the fun; whence, according to the theory of gravity, the elliptic arc which this comet would have defcribed, had Jupiter been abfent, must have been rather of the hyperbolic kind, with a confiderable alteration both of its velocity and direction.

Upon the fame principles may the variation of its inclination be accounted for. In this tranfit Jupiter was to the north, nearly perpendicular to the comet's path, which muft incurvate that part of the orbit towards itself, and fo increase the inclination of its plane to that of the ecliptic. Moreover, the comet, through this long continuance in the neighbourhood of Jupiter, when, being pretty remote from the fun, it afcended but flowly, its acquired velocity from the joint force of both the cen tres, must have been more than it could lofe in its recefs from Jupiter, under a fwifter motion, and in lefs time. Wherefore the proper velocity of the comet having been augmented by this excefs, it is probable, that its return may not be till after a period of 76 years, or even more, about the end of 1758,

or the beginning of the enfuing year. But this is faid conjecturally, and left to be confirmed or disproved by the event."

And again, "It is manifest now, that in thefe three phenomena (of 1531, 1607, and 1682), there is an agreement as to all the elements; which muft be accounted a miracle if they were three different comets; or indeed if they were not fo many acceffes of one and the fame comet towards the fun and earth in an ellipfis. Wherefore, if, agreeable to my prediction, it fhall return again about the year 1758, impartial posterity will not scruple to afcribe this invention to an Englishman.

"This then we may call the Mercury of the comets, as furrounding the fun with a fhorter period and a leffer orb than the reft, which expatiate to immenfe distances, and take up one or more centuries in coming round again, fo as for a fhort feafon only to be visible to human eyes."

Laftly,The comet of 1680, in that part of its orbit where it defcended towards the fun, came fo near the orbits of all the planets, that if any of them had happened to have met with it in its paffage, it must have produced very fenfible effects, and the motion of the comet would have been greatly disturb ed thereby. So that the fpecies of its ellipfe would have been much altered, as well as its plane and periodical time, efpecially in the cafe of a concourse with Jupiter. In its laft defcent, this comet left the orbits of Saturn and Jupiter but a fmall matter below it to the fouth. To the orbits of Venus and Mercury it ap proached yet much nearer, but nearer ftill to that of Mars. And in paffing the plane of the ecliptic, at its fouth node, its accefs to the earth's orbit was such, that had it happened one and thirty days later, it would have left the earth hard. ly a femidiameter of the fun to the N.; and doubtlefs by its centripetal force, (which with the great Newton we will fuppofe to be proportional to its quantity of matter), it would have effected some alteration in the pofition and fpecies of the earth's orbit, as well as in the length of the year."Thus far Dr Halley.

Sir Ifaac Newton has not said a word about the effects of comets on the earth or planets; and what little he has advanced in his laft edition concerning their periodical returns, is chiefly after Dr Halley, as appears by the following quotation.

"If comets are revolved in orbits returning into themselves, those orbits will be ellipfes." Again, "Dr Halley obferving that a remarkable comet had appeared four times, at equal intervals of 575 years; that is, in the month of September, after Julius Cæfar was killed; ann. Chr. 531, in the confulate of Lampadius and Oreftes; ann. Chr. 1106, in the month of February; and at the end of 1680; and that with a long and remarkable tail, (except when it was feen after Cafar's death, at which time, by reafon of the inconvenient fituation of the earth, the tail was not fo confpicuous); fet himself to find out an elliptic orbit, whofe greater axe fhould be 1382957 parts, the mean distance of the earth from the fun containing 10000 fuch; in which orbit a comet might revolve in 575 years and placing the afcending node in 2 d. 2 m. the inclination of the plane of the orbit to the plane of the ecliptic in an angle of 61 d. 6 m. 48 f. the perihelion of the comet in this plane 22 d. 44 m. 45 f. the equal time of the perihelion December 7 d. 23 h. 9m. the distance of the perihelion from the afcending node in the plane of the ecliptic 9 d. 17 m. 35 f. and its conjugate axe 18481,2; he computed the motions of the comet in this elliptic orbit; with which the obfervations from the beginning to the end do agree as perfectly as the motions of the planets do with the theories from whence they are calculated; and by this agreement plainly evince, that it was one and the fame comet that appeared all thofe times; and also that the orbit of that comet is rightly defined.

:

"This comet must have received an immenfe heat from the fun, and retain ed that heat for an exceeding long time. For a globe of iron of an inch diameter, expofed red-hot to the open air, will

fcarcely lofe all its heat in an hour's time; but a greater globe would retain its heat longer, in the proportion of its diameter, because the furface (in proportion to which it is cooled by the ambient air) is in that proportion lefs in refpect of the quantity of the included hot matter: and therefore a globe of redhot iron equal to our earth, that is, about 40,000,000 feet in diameter, would fcarcely cool in 50,000 years.'

Again, "As to the transverse diameters of the orbits of comets, and the pe riodic times of their revolutions, I leave them to be determined by comparing comets together, which, after long intervals of time, return again in the fame orbit."

And laftly, "Because of the great number of comets, of the great distance of their aphelions from the fun, and from the flowness of their motions in their aphelions, they will, by their mu tual gravitations, disturb each other; therefore we are not to expect that the fame comet will return exactly in the fame orbit, and in the fame periodic time.

"The comet of 1680 was in its perihelion lefs diftant from the fun than by a fixth part of the fun's diameter; and because of its extreme velocity in that proximity to the fun, and fome.denfity of the fun's atmofphere, it must have fuffered fome refiftance and retardation; and therefore being attracted fomething nearer to the fun in every revolution, will at laft fall down upon the body of the fun."

Thus far thefe great men from whence it may appear, how grossly the gloomy pamphleteer* has mifreprefent

ed

[Mr John Welley, the Methodist minifter, publifhed a pamphlet in the end of 1755, intitled, Serious thoughts occafioned by the late earthquakes at Lisbon, in which he fays, that Dr Haland obferves, that in this revolution it will move, ley fixes the return of the great comet in 1758; not only in the fame line, but in the fame part of the line, in which the earth moves round the fun; and that the confequence of this occurrence muft be, that in 1758 the earth will be burnt to a

coal.

Magazine, anfwers, that Mr Wefley has confounded the comet of 1682, whofe period is 75

To this Graticola, in the Gentleman's

years,

ed them; the comet of 1682, foretold to return in 1758, being in no fenfe to be fufpected of any of the dreadful confequences which that enthufiaft would charge it with. To speak the truth, if we look backwards, we fhall no where find any footsteps of difrangement or ruin brought about by any comet, on any of the planets of our system, at any time; and the very ancient obfervations of them all, recorded in Ptolemy, being exactly enough reprefented by our modern tables, is an unanswerable proof that no fuch thing has happened for at leaft 2000 years paft.

M. de Maupertuis, the illuftrious prefident of the royal academy of fciences at Berlin, clofes his ingenious treatife fur les differentes figures des aftres, in the following manner, having in the course of that work proved his affertions on mathematical principles of gravity. "Meff. Halley and Whifton have fancied, that comets and their tails may affect the planets with most tremendous alterations, as deluges, conflagrations, &c.; but we have fhewn that they may be productive of new and wonderful benefits unto them, fuch as producing the ring of Saturn and his fatellites, the fatellites of Jupiter," &c.

N

The PATRIOT, N° 4. Sept. 27. Otwithstanding your incredulity with respect to the neutrality, I anean to fay the capitulation, of Hanover, there is too much reafon to believe that it is fatally and irrecoverably concluded; and that, by the terms of con vention, the French are to keep poffeffion of the electoral dominions till a reconciliation fhall take place.

years, with that of 1680, whofe period is 575 years; and has, totidem verbis, applied what the Doctor fays of the latter, which will not appear ail 2255, to the former, which was expected in 1758 G. Witchell, another writer in that

Magazine, gives a calculation of the courfe of the comet which was expected in 1758; and thence concludes, that if that comet fhould pafs the plane of the ecliptic at the very time the earth is in the point the nearest to it poffible, it would be diftant from it fouthward no less than

four millions of miles.]

*

Ot the great advantage of which to that planet, fec Dr Gregory's Alt. on. vol. 2.

Hiftory fupplies us with innumerable inftances, where potentates have waged, if I may be allowed the expreffion, an amicable war, at the expence of their fub. jects blood, with no other view than to deceive their allies, and gain a plausible pretext of deserting them in the hour of neceffity.

Why was fo inconsiderable a force raised by the confederates in the empire?

a force indeed properly called an ar my of obfervation? For what could they be expected to do more than observe the enemy, and run away at the fight of them? Could it be fuppofed, that 40,000 men could defend themselves againft more than double the number, of equal, or rather fuperior difcipline? Might not Hanover alone, (had the been in earnest), instead of sending 14 or 15,000 men, have furnished double the number herself? And was not the elector rich enough to have hired as many more?

But perhaps it may not be improbable, that the prudent electorate chofe to make a double treaty ; one with the King of Pruffia, to keep him out, left he should over-run Hanover as he has done Saxony; and when they found the tide run against him, another with France, to let her in peaceably; for we find, by the terms of convention, that the electorate is to be put in fatu quo, and all damages, &c. to be made good.

What honourable conftruction can be put on fuch a proceeding? The fuperioris ty of the enemy might have been a reason against affembling the army, but it can be no excufe for disbanding it before it can be faid to have tried the hazard of the field. Were so many Germans armed, only to expofe their broad backs to the French, and difperfe at the critical time when they might have been of fervice? When the King of Pruffia, after the French had made fo large a detachment to reinforce Soubife, fent to the general of the confederate army, to acquaint him, that he had now a fair opportunity of extricating himself, how great muft have been his surprise, when, in return to his meffage, he received the news of a neutrality?—if

that