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Now fince the daily geocentric motion of Venus about the 3d of Mar. was jo n' 21" direct, and by Mr Thomas's observations we see that the comet, in the space of 24 hours, was 1° 10' nearer Verus, therefore its apparent diurnamotion was then 1' 21" direct, (3) so that Mr Thomas might conclude, without contradicting himlelf, that the comet viewed from the earth, about the 3d of March, appeared to move thro' the heavens in the order of the signs; and then what I inferr'd from thence must be sight. Mr Yate we see compuses its diurnal motion then to be at least 3'retrograde i but, as it appeared to run in a line that had about 20 inclination to the ecliptic, (4) its motion whether direct or retrograde was apparently much Nower (5) on the 3d of Mar, when ascending from its perihelion,
than (for fo much is the angle AC b) nor indeed could be postibly make it nearer : now Me Wrig be fago, bis trajectory was confructed from Mr Grobam's observations ; was it possible then that Mr Grabam, and crery body else, could be mistaken almoft a 'whole figo in the place of the comet Dec. 23? If not, it is evident, the comet must come in the direction b B, and if fo, he may bring hio peribelion more back till, if he pleases, but every body will
see, by that time he has Atraightened the line PF to make it agreeable to the former, 't will be a peribelion in a rigbe lioe or thereabout. - The direction of the line
B obliged Mr Wrigbe to place his peribelien as far forward as he bas done, in order to bring the fun into the focus of his Ellipfis; and if this removed the comet so far out of she way, as not to be feen from the earth oo the 3d of Mor. following, it was what he could not belp: he thought his theory had been true ; but the che comet leen in sunshine on that day, or after, has fully demonftrated the condary.
(3) So then by a nice calculation, after I had shewn him the way, he differs from me above 4'; a very small matter! bué the meaneft reader, by looking upon his scheme, may without calculation argue thus ; if Venus moving daily about 1° 37' from a cowardı g. doci ne the fame time, as viewed from å, appear to move il 11 direct ; then the comet moving from b towards F, muk needs, in the same time, appear to move above za di. re&; for the corve ecg and Bb F appear to be parallel from B to b; and consequently the comet in b, between Venus and the fan, muß move nearly the same way as Venus, and nearly as much
direet; seeing therefore that it did not do so, buc ame in a day's time J' 10'nearer Venus, it is mof evideot, that it did not more in the line P F.
(4) Fine calculations that can agree no nearer than 20 and 53° 45'inclination ! But as Mi Wrigbe's trajectory agrees with the observations taken on the 23d of Dec. and this does nor, nor cannot; I shall cake the liberty of following Mr Wrigbe, who appears not to have been mistaken, as far as be depended upon observations, and not upon theory.
(s) I said formerly, the comet might ron 2 or ze along the heavens while it gained 2010 'of Virus: I will here fhow that it might run above 30° along the heavens while it gained 110', provided it moved with 53° 45'inclination to the ecliptick, atd that it was in a node, a: Venus was ncarly, on the 3d of Mar. Lo the oblique spherical triangle A B C(fee the figure above) we have given the side A B the distance of the comet hom Venus, Mar. the
3d, 268 50', che fide B C the diftance of the come from Venus, Mar. ebe 4 b, 25° 40', and the angle A, the inclination of the comet's course to the ecliptick, 53°45', co find the fide ac: Let fall : perpendicular from B to D, and say thes,
As the co' angent of A B 268 go
To the taogent of the segment À D'76 39
Is to the cofine of A B 16 39;
To the cofiac of ihe segment D C 14 36. Add the two segments together, and they give you the curve AC 32° 15'; and so far might the come move along the heavens, and yet be but 1° 10' nearer Venus, which by, lecting fall a perpendicular trom the argle Cro E, may be found to be no less than 18° 33' retrograde; lo rery little is there in what this gentleman saya so positively, ibat ibe apparent motion of tbe comet was mucb florker, Inde:d, if the comer had before this crofted the ecliptick, (ao no doubt but it had) and was in any point between A and D, then the nearer i: was tu Dihe g ea'er would be ibe angle A, and of coosequence fo moch the lefs the side AC; tho'rtili I believe every veb ased reader will admit that between 1° and 38° there was room enough, in all cooscience, tos a retrograde motion conurent with my parbris,
than it had been when descending towards it, which motion would then have gradually increased, if, according to Mr rate's hypothesis, it had approach'd the earth in the strait line A d, P. 201. consequently this comet on the 3d of Mar, was not approaching to, but receding from the Earth in the direction b F.
Mr Yate says thar, “ From this self-evident proposition every “ thing, the farther ic is from us, the less it must appear to us, & vice « verja, — demonstrated, &c.” This proposition will only hold good in objects that appear under the fame angle, (6) when at the same di. ftance from the eye of the observer ; and, since the tails of comets are observed to be sometimes greater, sometimes less, when at the same di. stance from the observer's eye, what Mr Yate has inferr'd from this propofition (7) must be false, and what Mr Thomas says of the late comet's tail encreasing from 10 to 40 degrees, is very confentaneous to Sir Isaac's theory. For by the foregoing hig. the comet's tail would about the 22d of Fr. appear very small, both by reason of its vicinity to the fun, and of its bearing almost directly towards the earth ; and it may reasonably be fuppos’d that, while it was moving from P to b (as its distance from the sun would not be much augmenied) its heat and consequently its tail would considerably encrease ; that when it was arriv'd at b, its tail, being nearly in the molt advantageous situation, would appear largelt, seeing that its distance then did not much exceed its distance from the earth on the gth of Feb. For Mr Thomas says, “ Its head appeared very large " and bright; and, on a close inspection, I have perceiv'd it when the sun " has been about one diameter above the horizon.” But on the 13th of Feb. in the morning this comet appear'd superior in magnitude, and nearly equal in luftre (8) 10 Venus ; and I saw it then myself 8 or 10 min. after the sun was above the horizon, and might have done so much longer had time permitted ; therefore its nucleus may reasonably be conjcctured to have appeared nearly of the same magnitude to the gth of Fib. and the 3d of Mar, following; tho' probably this comet did Mine (as others have been observed to do) with more vivacity (9) when seen by Mr Thomas, because of the increase of heat it had acquired from the
I i (5) If it holds good thus far, it holds good far enough for my purpose; for, surely, all Spberical bodies muit app war under the fame angle at the same diftanee; and my argument was not drawn from the rail, but from the Spberical head of the comet, which i conclude ed (according to Mr Wrigbt's confraction) mu& be a third part turther from the carth on the third of Mar. than it was on the 23d of Dec. and consequently, if it was but junt feen on the 23d of Dec. it was not possible to see it on the 3d of Marcb; but it was seen in sunshine on the 3d (it not on the zih) of Mar, and hence I plainly demonftraced that it muft be vaftly nearer the earth than that theoty fopposed.
(7) What I laid of the comet'o tail was not inferred from this propofition, as the weak. eft reader must see, but from its bearing away almost dire@ly from tbe earib; and consequently, as its angle was gradually growing less, and its distance encreasing (according to that theory) it muft of neceffity grow shorter as it ascended from its peribelion ; but the contrary is known to be true, and therefore the comet moft take quite another course. He that can't see the strength of these two arguments, muft certainly, from the weak. nefs of his intellectuals, be is capable of convidion.
(8) I don't love to queftion any body'o veracity, but I myself law the comet one morn. ing. (the fame morning for cught I know) and tho' it appeared about as big, yet it had nothing of the brighinelo of Venus: I believe this gentleman is the fift man in the world that ever saw a comet shining with the luftre of Venus, tho' I fancy Venus itself could not be seen after sun-rifing, in that part of its orbit.
(9) When Mr Davies faw the comet, it was nearly equal in luftre to Venus; but when Mo Tbomas saw it, probably it Ihone as bright or brighier chan Venus, Credar 34 daus apella,
sun ; hence, by the foregoing proposition, it is manifeft, that this comes was nearly equi-distant from the earth on the 9th of Feb. and 3d of Mar. and that Mr Thomas, if Mr Yate's hypothesis of rectilinear motion be true, would haye seen it, notwithstanding the consumption it could, in that space of time, have undergone, without a close inspection (10) even tho' the sun had been much higher.
Seeing then, that, by all observations, the late comet did move round the sun, and that, in all its appearances, it did accurately answer, and wonderfully confirm Sir Isaac's theory; Mr Yate's heliocentric (11) quib ble, and all that has yet been offer'd to the contrary, are to no purpose.
Hevelius, as is well known, who embrac'd the hypothesis of the rectilinear motion of comets, having the opportunity to observe many of them accurately, complain'd that his calculations did not agree with his oblervations, and found reason to believe that the path of a comet was bent (12) into a curve line concave towards the sun.
If comets, as Mr Yate supposes, be meteors form'd by the sun, they are certainly meteors of a monstrous bulk, for their diurnal parallax being not perceptible, is a plain proof of their great distance from the earth; and conlequently their magnitude and velocity * (13) must be very great also, which is not at all suitable to a meteor. And therefore unless Mr Yate produce good reasons, how the fun could form such a prodigious mass of a meteor at so vast a distance from itself; how such a body, to which himself attribuics gravity, vol. 13. p. 193. A. could independently acquire fuch an impetus as to force (14) a rectilinear passage thro this gravitating planetary system, a system strongly endow'd with attractive qualicies; and why all comets are observed to be either approaching to, (15) or receding from the fun; fince by his hypothesis they may be form'd any where in this system, and would certainly, some time or other, have been seen traversing regions, vastly remote from, and opposite to him, (16) and in such a direction, that a vilble approach to him would have been impossible: I say until these objections be fully
clear'd Every body knows that the velo- been considerably swifter than the city of the late great comet muft have earth's.
(10) On a close inspection, it was seen on the coast of New Holland after fun-rifing, when there was but one morbematician to look at it; in Great Britain it was seen, I be lieve, but by one, when there were many thousands to observe it.
(11) The question between me and Mr Dovies is, Whether Mr Thomas by direEt in tended the beliocentric, or geocentric motion of the comet? If the former, Mr Davies mui be very obstinate io fill infifting on the latter, and making that author contradia himself. (12) Hevelius believed the path of a comet to be bent, cho' Aill be held it to be ftrit. -Fye! Fye! for shame let's have no more such ituff.
(13) As to the magnitude of comets, and how they are formed, I have already faid enough in my new theory; as to their velocity, every body knows, that their tails move as tatt as their heads ; yet their tails, in the opinion of the great Sir Isaac Newton, are a meer vapour ; and consequently, a meer vapour may move as faft as they do, let them move as fast as they will.
(14) From the free motion of the comers' tails, Sir Isaac Newton argues the necessity of
(15) Surprizing ignorance ! Can this gentleman Atrike a right line thro' a circle, that thall not approach towards, and recede from its center? If the motion of the cometa is rectilinear, this muft neceffarily be the case.
(16) Comets have been seen at a vaft distance from the sun ; tho' Aill, if they moved is right lines tb.y must for chaf very reason approach acarer, or go further from it.
elear'd up, and until better demonftrations prove the truth of their rectilinear motion, the Newtonian theory stands unshaken. (17) Wigton, 08.3.
Your oblig'd humble Servant, J. D.
(17) How can it be thaken, when it has the wonderful traje&tory of Mr Davies to sup. port it? a trajectory that is no more than 28° of longitude, inconsistent with Graham's obfervation on the 23d of Dec, and in which the comet must move but 1° too much dine, on the 3d of Mar. according to Mr Davies's own calculation.—- If construction and alculation fail, yet fancy, we fec, is fufficient to keep it Ateady.
N. B. The above having by J. D. been fent to Mr Teie, he added these Notes by way of Apwet,
Remarks on a Differtation concerning MELCHIZEDEK.
may be allowed a place in your Magazine, Or Miscellaneous Correspondence.
There is just published, a dissertation on the biftory of Melchizedek : in which the writer pretends to prove, that Abraham did not give tythes to Melchizedek, but Melchizedek to Abraham. To which purpose he asserts, " That that history does not yield a proper ground for such opi“ nion to be built upon, viz. that Abraham gave tythes to Melchizedek, a but the contrary ; and, “ that the historian is very particular and “ express that it was Melchizedek, p. 12, 13." It is granted by some learned men, that the words, independant of the context, and be gave bim tythes of all, Gen. xiv. 19. leave doubtful who it was that gave rythes, Abraham or Melchizedék. Vid. Patrick in loc.
But this writer, who can see farther than other people, says, “ the historian is very par“ ticular and express that it was Melchizedek, who gave tythes to Abra. “ bam, and not Abrahan to Melchizedek.” To lessen the weight of his authority, without any nice criticism, 'tis fufficient to observe, that the Jews, for whose immediate use the pentateuch was writter., have generally understood this pasage of Abrabam, that Melchizedek received tythes from him. “ This Melchizedek, faith Josephus, B. I. C. 10. enter. “ tained the soldiers of Abram with great holpitality, and courteously “ furnished them with every thing neceffary unto human life, extolling “ at his feast the bravery of Abram, and giving glory unto the most high
God, who had put his enemies into his hand. On the other hand, “ Abram presented unto him the tenth of all the spoils which he had “ taken from the Asyrians, which he received at his hands.” Now can it be fairly thought, that the Jews, who may be supposed to understand their own books as well as the differtator, and who wanted for no respect for their ancestor, nor skill, nor vanity, to place hın in the most advantageous light, would, from this history, believe their father paid sylbes to Melchizedek, if the contrary was, therein, very particular and express? Be this as it will.
From this assertion the dissertator proceeds to observe, “ That the cir« cumstances which attended the case do not admit it to be otherwise. “ For, first, Melchizedek had done nothing to, or for Abraham, which
“ called for such a grateful return; whereas, Abraham had laid Melcbia “ zedek and all the people in that neighbourhood under an obligation of
gratitude to him, in that he had rid the country of their great oppref “ jor, p. 13
In answer to which, from the history it appears, (...) That Melchizedek was a neutral prince in the quarrel and war of the kings; and, consequently, Abrabam in engaging with, and beating Cbedorlaomer and his confederates, had done nothing to or for Melchizedek which called for any such grateful return from him. Melchizedek might have enjoyed the benefit of his neutrality and pacific disposition, let which fide foever had the better. (2.) It was otherwise with Abraham: He was nearly concerned, and very lensibly interested in the late progress of these princes arms. They had plunder'd Sodom, and took Lot, Abrabam's nephew, and all his goods, and carried him away captive, v. 11, 12. That his deceased brother's son, whom he had brought up with him from Haran, from his native country, from his kindred, and from his
father's house, and who for many years had sojourned with him, till lateily obliged to separate for mutual convenience and accommodation, (Gen.
xii. 1,4. xiii, 1, 5,6.) that he, I say, should now be pillaged of his