MONTHLY CATALOGUE, For AUGUST, 1757. MISCELLANEOUS. Art. 1. An Account of the Discoveries concerning Comets, with the Way to find their Orbits, and fome Improvements in conftructing and Calculating their Places. For which Reafon are bere added, new Tables, fitted to thofe Purposes; particularly with regard to that Comet which is foon expected to return. By Thomas Barker, Gent. 4to. 2s. 6d. Whifton. HE Aftronomy of Comets (as Dr. Halley juftly observes) may properly be faid to be yet in its infancy, no advances having been made in it before the last century. With regard to the antients, they knew little or nothing of their nature or motions. Diodorus Siculus, indeed, tells us, that the ancient Egyptians and Chaldeans were able, from a long series of observations, to predict the appearances of Comets but it must be remembered, that they are alfo faid to have known the times when storms and earthquakes would happen: and, therefore, it is natural to conclude, that their knowlege confifted wholly in aftrological calculations. They, however, confidered them as wandering stars; an opinion, which all the antients were far from embracing; for fome fuppofed them to be only mere appearances, formed either by reflection or refractions of the fun's beams, having no real or distinct subftance from other celeftial bodies. Others believed them to be fiery meteors, generated of bituminous exhalations from our terraqueous globe, which being elevated to the higher regions of the atmosphere, were there set on fire, and continued their appearance till all their fulphureous particles were confumed: while others confidered them only as ominous phænomena, difplayed by the Supreme Being, to terrify mankind, and warn them of the approach of fome dreadful calamity. The fame opinion prevailed during the dark ages between the decline of the Roman Empire and the Reformation; and Apian was the first, who, about the year 1580, began to obferve their motions aftronomically. But it is to Sir Ifaac Newton that we are indebted for a true theory of the motion of Comets; and from the lights he has thrown on this abftrufe part of aftronomy, there is reafon to hope that fucceeding Aftronomers will be able to carry this part of fcience to the greatest degree of perfection. In order to this Mr. Barker has given us a new table of the parabola, by which the fpace and dittance from the focus, at all angles, are fhewn and which is, therefore, of the greatest ufe in calculating the place of a Comet. He has also added the method of calculating this table, and the manner of conftructing a Comet's motion in the most easy manner. The junior Mathematicians will be very much obliged to Mr. Barker, for the pains he has taken in explaining the famous problem of Sir Ifaac Newton, for finding a Comet's orbit from three obfervations. The Comet which is next expected to appear, and which gave occafion to the publication of this, as well as feveral other pamphlets on the fame fubject, has been obferved to return at the different periods of feventy-five and feventy-fix years alternately. The difference," fays Mr. Barker, is very great, confidering how true the Planets ⚫motions are found to be; yet I fear we must not expect the fame ⚫ regularity in a Comet's orbit as in a Planet's, they being fubject to many greater errors: first, croffing all or moft of the Planets paths, they may come nearer to one or other of them than any of the Pla⚫nets do to each other, and be more effected by their mutual attraction; efpecially if near Jupiter or Saturn, the greatnefs of which ⚫ bodies, weaker power of the Sun, flownefs of their motion, and, confequently, long continuance near one another, and the direc tion of the Comet's path nearly toward the Sun, all join to make the alteration of its orbit more fenfible. 2dly, a fmall change of angle will make little difference in a Planet's orbit, which is always nearly perpendicular to the Sun; but when a Comet's path makes only five or ten degrees angle with a line from the Sun, a little va'riation will bear a greater proportion to that fmall angle than to ninety degrees. 3dly, As a Comet's greateft diftance is many times its leaft, if by a Planet's attraction the perihelion is altered but a few miles, that may be greatly multiplied in the aphelion; and iề the angle at first is changed but one minute, it may make a great ⚫ alteration of length, in running four times as far as Saturn, and ⚫ backing again. 4thly, There is but little difference in the velocity of a body, going round the Sun in one or two hundred years, and of keeping a perfect parabola; fmall, therefore, must be one revolving in feventy-five or feventy-fix years, efpecially if the fame power which increases its velocity, fhould make its perihelion dif tance greater. Now the Comet in its defcent towards the Sun, may be near Mars, but that being small will hardly affect it much; again, in going from the Sun it may país near Venus, a little before it gets to the defcending node, and near the earth a little after it : if then one or more of thefe Planets fhould be in that part of their orbit when the Comet paffes by, they may make some change in ⚫ its motion.' ་ In this manner Mr. Barker accounts for the unequal periods of Comets; but whether they are owing to thefe, or other caufes not yet discovered; or whether all the Comets are fubject to thefe irregular.t.es, must be determined by future obfervations. Art. 2. The Theory of Comets illuftrated; in four Parts, 1. An Effay on the Natural History and Philofophy of Comets, being the Subftance of all that has been hitherto published on that Head. 2. Tables containing the Elements of the Theory of a Comet's Motion, (in a Parabola or an Ellipfis) with their Nature and Ufe explained. 3. The Method of Conftructing the Orbit of any Comet, and Computing its Place therein; its Latitude and Longitude, as feen from the Earth or Sun; its Dif tance, Velocity, Magnitude, Length of Tail, and other PartiΝ REV. Aug. 1757. culars eulars relative thereto. 4. The Method of delineating the vifi ble Path of a Comet in the Heavens, on the Surface of a Celeftial Globe; and for drawing the Trajectory by Protraction with Scale and Compaffes. The whole adapted to, and excmplified in, the Orbit of the Comet of the Year 1682, whofe Return is now near at hand. By Benjamin Martin. 4to. 2s. 6d. Printed for the Author. We have here a concife fyftem of the Philofophy and Aftronomy of Comets, extracted from the belt Writers on thefe fubjects, the principal of which are, Hevelius, Fhimftead, Newton, Halley, and De la Caille. The principles of Cometary Calculation are laid down in a plain and intelligible manner; fo that thofe who are acquainted with the doctrine of Trigonometry, will eafily understand the feveral precepts delivered in this treatife, and be able to calculate the place and diftance of a Comet, borh from the Sun and the Earth, together with its longitude and latitude in the Ecliptic, at any given time during the Comet's appearance. Art. 3. An Account of the Remarkable Comet, whofe Appearance is expected at the End of this prefent Year 1757, or at the Beginning of the Year 1758: With the dreadful Effects that may probably happen by its near Approach to the Earth's Orbit. Likewife Obfervations on the two other remarkable Comets, which are expected to appear in the Years 1789 and 2255. The whole illuftrated with Reflections on the general Conflagration, &c. &c. 8vo. Is. No Printer's name. The obfervations on Comets in this pamphlet are very fuperficial and trifling; and thofe relating to the Comet expected fhortly to appear, are purloined from a print lately published by Mr. Martin, repie fenting the orbit of the faid Comet. Art. 4. A Difcourfe on Comets. Containing a brief Defeription of the true Syftem of the World, and an Enumeration of all the Difcoveries which have been yet made concerning thefe temporary Appearances, with respect to their Orbits, Forms, Velofity, Magnitudes, Distances, Tails, &c. particularly that whofe Return is expected in this or the following Year. Extracted from the IVritings of Sir Ifaac Newton, and other Aftronomers. To which is added, the Opinion of that illuftrious Author concerning the Ufe of Comets, the Origin of Matter, and his Definition of the Supreme Being of the Univerfe. Collected by J. L. Cowley, Mathematician. 8vo. 1s. Payne. This pamphlet is chiefly intended for thofe who have not made any confiderable progrefs in mathematical studies, but at the fame time are delirous of forming fome idea of the fyftem of the Unive:fe, and particularly of thofe revolving bodies called Comets, or Blazing Stars; and to fuch it will prove very useful, every thing relating thereto-be ing laid down in a plain and familiar manner; and the feveral advances and improvements that have been made in this branch of Aftronomy, particularly enumerated. Art. 5. A Journey from Calcutta in Bengal, by Sea, to Bufferah: from thence across the great Dejart to Aleppo: and from thence to Marfeilles, and through France to England. In the Year 1750. By Mr. Bartholomew Plaifted, in the Eaft-India Company's Service To which are added, Directions by Capt. Eliot Eliot, for paffing over the little Defart, from Bufferah, by the Way of Bagdat, Moujul, Orfa, and Aleppo. Published from his original Manufcript. 12mo. 2s. 6s. Newbery. This book principally confiits of Dire&ions for Travellers, who may hereafter happen to make the fame tour that our Author has taken; particularly with regard to the management of Expences, Conveniences, &c. As to the defcriptive part of the work, Mr. Plaifted has faved himself the trouble of drawing up any thing of that fort, by borrowing mottly from former Travellers, whofe accounts are already before the public;-this, however, he does not do as a Plagiary, but honeftly tells the truth. Thus, for inftance, he acknowleges that his defcription of Aleppo is taken from Dr Ruffel; whofe valuable work we lately had the pleafure of perufing. But as to most of his other defcriptions, viz. of Cyprus, Rhodes, Lyons, and Marseilles, he contents himself with barely intimating, that he had them from Authors of credit, &c. Upon the whole, tho' not a very important performance, Mr. Plaifted's Journal is a ufeful, and, in fome degree, an entertaining one: as he writes like an honcit, and a fenfible man, tho' not mach like a man of letters. * Review, vol. XV. page 135. Art. 6. A Treatise on Places and Preferments, especially ChurchPreferments. To which is added, a Letter concerning the Caufes of Earthquakes, lately published in the Public Advertijer, at the Request of fome Gentlemen; with a Supplement, containing fome Remarks upon a Letter fince received from a learned Correfpondent upon the fame Subject. By the Rev. W. Webster, D. D. Vicar of Ware and Thundridge in Hertfordshire. 8vo. gd Ruffel. This Author fets out with comparing the Body-Politic with the Animal Body; the various parts of one, to the great variety of arts, fciences, employments, places, and offices of the other: and, by a parity of realoning, infers, concerning the latter, that they are all of them ufeful toward the profperity of the whole! A affertion fo unlimited, that, fince his title page fhews places and prefer. ments, efpecially thofe of the church, to be the objects of his atten N 2 tion, tion, we believe none but Placemen will affent to it. But, as Hudibras quaintly remarks, No Argument like matter of Fact is; Therefore, if Spain, Portugal, or Italy, who are bleffed with a comfortable swarm both of church and civil Placemen, are the happier, or the richer, on that account, then the Doctor's affirmation is true. Our Author ufes many arguments to explain and defend the claims of the Miniftry to rewards, dignities, and honours; the infertion of which would doubtless have greatly enriched our Review, had we room for them: one, however, we cannot overlook; as it is a plea for the enjoyment of them which the most abandoned Athiefs, or inflexible Heretics, cannot, with all their fophiftical reasonings disallow; namely, the pofitive appointment of the Law of the Land; an argument, we must concur with him in calling unanswerable.-He next appeals to the exprefs command of God, in his written word.' Which exprefs command is a paffage in St. Paul, importing, Those who have laboured in the word and doctrine are worthy of double bonqur. But, afking Doctor Webster's pardon, this text he seems to have strangely mifunderstood; fince, whatever degree of reverence may be due to Preachers of the uncorrupted Gofpel, it cannot intend lucrative or worldly dignities, fo often, and fo emphatically, difclaimed by the meek and lowly Jefus. The Doctor, who appears extremely fond of parallels and fimilies, illuftrates his argument by a comparison between Profeffors of the Gofpel and Profeffors of Phyfic: and after fuppofing, and farther fuppofing, Aill unfatisfied, he fhifts the fcene, and you again behold them likened to a number of Trustees for a charity; and, with the affiftance of a mathematical fimile, concerning the points of contact be. tween two planes, as likewife between two globes, the curtain drops, and the matter is left-just as it was found! As the Clergy, according to our Author, fhould be gratified with diftinctions of honour and profit, proportioned to their merit, (for he protests against the Levelling fcheme) the impoffibility, he afferts, of doing this without a junction of Livings, naturally leads fo true a fon of the church to introduce a few words in defence of Pluralities; adding, I am perfuaded that the credit and intereft of the body of the Clergy cannot be fupported under the prefent ftate of the church without them.'-Another great grievance prefenting itself to the good Doctor, relates to country Minifters in market-towns; many of the people, he fays, are low in their extraction, narrow in their education, turbulent in their nature, and ungovernable by any thing but mere Power; and if any one fpends more money, or has more to fpend, than the poor Vicar, he will think himself fo much a better, and a greater man than his Paftor. From fuch complaints as thefe, a harth-judging Reader might be led to conclude, that the Doctor would rather fee every Clergyman the richest man in his parith, than the parishioners notions rectified by true chriftian principles ! The |