I be unavoidable, (witness the new terms and characters in the method of Fluxions) he objects to prime member, function, &c. as terms never heard of before.-Alas! how egregioufly does he betray his ignorance! ridiculous enough, indeed! to fet up for a Critic in Algebra, and never heard of Algebraic Quantities, and the term Function !I am under no apprehenfions, that the opinion of fuch a Critic can have any weight with the public: therefore, to the fuppofed faults he has accufed me of, with refpect to my method of proceeding in the investigation of propofitions, I fhall not give myself the trouble to fay any thing. Walton, near Peterborough, I am, Gentlemen, Your moft humble Servant, MONTHLY CATALOGUE. For AUGUST, 1759. MISCELLANEOUS. Art. 1. A Difcourfe delivered in the Theatre at Oxford, in the Senate-houfe at Cambridge, and at Spring-Garden in London, by Thomas Sheridan, M. A. Being introductory to his Courfe of Lectures on Elocution and the English Language. 8vo. Is. Millar. E find very little in this Difcourfe either to applaud or centhe ftudy of oratory,-under fo able a profeffor as it is infinuated Mr. Sheridan would prove to be, if placed in either Univerfity, and encouraged by a handfome falary. Mr. Sheridan talks much of the evils attending our neglect and difufe of elocution, and the great good that would follow the cultivation of its study and practice. He does not, however, point thefe out very clearly: and, indeed, while we admit the force of oratory, and know that its bufinefs is rather to inflame the paffions than inform the judgment; to perfuade rather than to convince; the art of eloquence, however eflential to the character of a polite and learned nation, will be made alternately the political inftrument of good and evil, according as its profeffors and adepts are actuated by good or evil purposes. Art. 2. The Doctrine and Practices of the Jefuits. Containing their Grounds, and a Detection of their fecret Defigns, and bloody Projects. In a Letter to the Editor, from a Member of the English College of Secular Priests at Lisbon. 8vo. I S. Dilly. 3 We We have no persuasion that this is really a Letter from an English fecular at Lisbon, but rather look upon it as the pious fraud of tome zealous Proteftant Writer at home, whofe intention is to inform us of the inflitution, doctrines, progrefs, and practices of the Jefuits; and which,' he fays, will ferve to throw a light upon their part in this late confpiracy; [the attempt on the life of his Portuguese Majefty] to give thofe who are not well acquainted with the religious inftitutions in the Church of Rome, a proper hint to know how to distinguish a member of this order from all others, and to caution every station and degree of mankind, to avoid a Jesuit, as the poifon, the pest, and destruction of individuals, focieties, and ⚫ governments.' Page 6. 6 Art. 3. An Account of the Methods used to defcribe Lines on Dr. Halley's Chart of the terraqueous Globe; fhewing the varation of the Magnetic Needle about the Year 1756, in all the known Seas; their application and use in correcting the Longitude at Sea; with fome occafional Obfervations relating thereto. By William Mountaine, and James Dodfon, Fellows of the Royal Society. Mount and Page. The chart, of which this little pamplet gives fome account, was originally conftructed by the celebrated Dr. Halley; and is, perhaps, one of the most useful difcoveries, that has hitherto been made in the practical part of navigation: and therefore, we were furprized to find the ingenious gentlemen, who have re-conftructed this chart, complaining, That it has never returned its firft charge." This is, indeed, poor encouragement for those who undertake fuch Jaborious tasks, for the good of the public. Its utility is allowed by all; and yet it seems very few have brought it into practice. Surely, a person must have little regard for his reputation, his fortune, his life, who shall undertake to conduct a fhip through the pathless ocean to some distant coaft, without taking with him a chart, which may prove of the greateft fervice in his voyage. It is well known to all, who have made obfervations on the magnetical variation, that its mutation is remarkably irregular in diffe rent parts of the world; and confequently, the only method of conftructing a variation chart, is by collecting a large number of obfervations made by artists in their voyages, and transferring them to the chart. This is the method thefe gentleman purfued, and the reader may form fome idea of the pains they must have taken, from the following account of the materials they were favoured with, and the number of journals they perufed for this purpose. The honourable the Commiffioners of the Navy,' fay they, obliged us with an order of free access to all their matters log-books ⚫ and journals. 4 The Directors of the honourable the Eaft-India Company, indulged us with the like privilege. The Committee of the honourable Hudfon's-Company, gave us fet of obfervations made in the tracks of their trade, and tabu•lated by fome of their captains. a • Dr. Dr. James Bradley, Regius profeffor of Aftronomy, and F. R. S. favoured us with several obfervations made at the royal oblervatory at Greenwich. John Hyde, Efq; F. R.S. communicated a fett of useful obfervations, extracted from two journals, kept on board the Triton ⚫ and Britannia Eaft-Indiamen. A correct journal kept on board the Delawar Eaft-Indiaman, was handed to us by a gentleman unknown. Capt. George Snow, furnished a confiderable number of obfervations, made with great care and accuracy by himfelf, in feveral 'fucceffive voyages to, and from Barbadoes and Virginia, together ⚫ with several remarks upon the fubject. Mr. Mungo Murray, author of a Treatife on Ship-building, prefented us with feveral obfervations taken on board the Prince Edward and Chefterfield Indiamen, and his Majefty's fhip the • Neptune. • All which affiftance is gratefully acknowledged. Among the journals which we examined, it was found, • That in fome wherein such observations were found, no account ⚫ of difference of longitude was kept. That few contained obfervations made near at home (as fuppofing the variation there generally known) in any harbour, or ⚫ even within fight of land. That, where an account of the difference of longitude was kept, feveral inftances have been observed in journals of identical voyages, wherein the fhip's place, at the fame time, has been differently determined; And, "Some journals kept on board ships in the fame fleet, have differ⚫ed more confiderably. Obfervations, therefore, of the variation, made under any of the above disadvantages (however ferviceable they might have ⚫ been) were rejected; a confiderable number occurring, which were • made by thofe, whofe accounts were as correct as the practice of ⚫ navigation will permit. But the difference of longitude made between two ports, by ⚫ different ships, or by the fame fhip in different voyages, frequently difagreed with each other, and with the chart. Therefore, in order to apply obfervations made under fuch cir<cumftances, we were obliged to reduce the difference of longitude by account, to the standard of the chart; for instance, let us fuppofe a fhip's journal makes the difference of longitude from the weft-end of Madeira to Barbadoes, to be 44 deg. 44 min. and that according to the chart, it is but 40 deg. 40 min. fince it cannot be granted, that the error of 4 deg. 4 min. can arife at once; it will therefore be more rational to fuppofe it diffufed through the whole voyage; and then to rectify it, there must be a decrease of oned egree in eleven; now if an obfervation of the variation was made, when according to account, the fhip had made 30 deg. 48 min. difference of longitude from Madeira; if the eleventh Rev. Aug. 1759. ⚫ part N part thereof, (viz. 2 deg 48 min) be taken therefrom, the remainder (28 deg. o min.) will be the difference of longitude from Madeira according to the chart; and if thereto (18 deg. o min.) the difference of longitude between London and the weft-end of Madeira be added, the fum (46 deg. o min.) will be the longitude of the place of obfervation, according to the graduation of the chart. But as the longitude of the chart is graduated only at the equator, and the la itude but in two places, and thofe 230 deg. o min. from each other, we were obliged to make use of an inftrument to apply thofe graduations, in order to fix the place of obfervation expeditiously. At the four corners of a rectangular plane table, juft big enough to contain fixty degrees of longitude, and as many of latitude, were placed four flat-headed fcrews, to keep a piece of the chart of that magnitude fecure in its place; on the frame of this table, the degrees of latitude from o deg. to 60 deg. were graduated and bifected; and on a T ruler alfo thofe of longitude; now if the edge of the ruler be applied, fo as to pass over the latitude of the place of obfervation on the frame, and a protracting pin be moved along it to the longitude, and there ftuck into the table, it points out the place of obfervation on the chart; which place was marked with figures, expreffing the number of degrees of variation there • obferved. A great number of obfervations made near the fame time, being thus transferred to the chart, enabled us to approve of fome and reject others, according as they were fupported or not, by concurrent teftimony; and thence to draw lines representing the ⚫ variation at that time. There are indeed fome lines described on the chart, that have not fo great a confirmation as that above-mentioned; but these lines are diftinguished from the others, by being dotted, or having frequent breaks in them.' Our authors next proceed to give us an account of the use of this fea-chart, and mention the applause it received from Don Ulloa, a celebrated Spaniard; of whofe voyage to South America, our readers had an account in the 19th Vol. of the Review, p. 286. As it will be neceffary to re-conftruct the lines of variation on this chart periodically, it is incumbent on all perfons who have op. portunities of making obfervations on the variation of the needle, and are defirous of being ferviceable to the public, not to omit them, and to take care that they are made with accuracy. The mariners are particularly interested in thefe obfervations, and therefore it is natural to think they will be affiduous in the performance and in order to this, the following method, pointed out by our authors deferves their attention. As there are feveral perfons in every confiderable fhip, who are expected to keep journals; fuppofe fo many of them as can be fpared from neceffary bufinefs, be fummoned by the commander once a day, and required to give an account of the place of the fhip, at the laft noon; when, fhould it happen (as it bas been before obferved) that any two or more of them difagree ⚫ therein therein, let their quotations from the log-board, their allowance for variation, leeway, currents, fwells, indraughts, &c. nay, even their computations be compared; and from that com parison, by agreement of perfons appointed, let fuch a latitude and longitude, as shall feem moft reasonable, be fixed for the fhip's place, at that time, and entered in a book kept for that purpofe (which might be called, not the captains, lieutenants, c. but the fhips journal), with the particulars of all the allowances made in the calculation thereof, and the most material occurrences; especially obfervations of the variation, made as often as may be, particularly near or upon the fhore; of the latitudes, * and longitudes of places, made alfo on fhore; and of the direction and velocity of currents, &c. When a fhip comes into port, let the difference of longitude ⚫ between the place failed from, and the port arrived at, according to every particular man's account, as well as by the ship's jour⚫nal, be entered therein. Where several ships fail together, fuppofe the admiral, or com'modore, was to fummon all the captains as often as weather, &c. will permit, and in this meeting that all the particular fhips journals were produced and compared; in order therefrom, to ⚫ form a fleet's journal, in the fame manner as before Suppofe again, that these fhips and fleets journals, and all • other accounts relating to this fubject that should come to hand by this, or any other more convenient and practicable method that may be hit upon, were examined at proper periods, by per⚫ fons appointed for that purpose; might not more accurate charts ⚫ be made from them, than any extant? might not the variation, carrents, &c. be fo far accounted for in moft parts of the world, as to render the business of navigation much less uncertain and ⚫ hazardous than at prefent; and would not fuch a knowledge of ⚫ the variation as has been obferved before, even practically deter'mine the longitude at fea?' We cannot conclude this article, without wishing that the ingenious Mr. Mountaine (the other gentleman, Mr. Dodfon, being ince dead), may meet with better fuccefs in this edition, than in the laft; as it will not only be an encouragement to learning and affiduity, but prove that our mariners know how to value a useful invention. Art. 4. The genuine Remains in Verfe and Profe, of Mr Samuel Butler, Author of Hudibras. Published from the original Manufcripts, formerly in the poffeffion of William Longueville, Efq; With Notes by R. Thyer, Keeper of the Public Library at Manchefter. 8vo. 2 vols. 10s. Tonfon. There is no doubt but the pieces here published, are the authentic productions of the fame pen to which we owe the celebrated udibras. Mr. Thyer has fufficiently established this point, both in his propofal for printing these pieces by fubfcription, and in his preface to the prefent edition. |
