teachers is too fhort to be either entertaining or fatisfactory. In feveral places of this work, a fpirit of rancorous Judaifm is very evident; and from the general tenor of the Jewish Rites and Ceremonie, as they are here deferibed, we fancy that few, who have any religion of their own, will be induced to change it for that of the Jews, if they form their opinions from the account of David Levi. After a fhort account of brotherly love and charity, he enters upon the Minfha, of which he gives a long account, as well as of the Oral law, and its teachers, which fills about a third of the volume. Thofe who have a defire to investigate this matter, we refer to the work itself. Some parts of this account are curious, but it has very little in it that can intereft any reader, but a Jew; and the lift of ART. XVIII. Annus Mirabilis; or, the eventful Year Eighty-Two. An Hiftorical Poem. By the Rev. W. Tafker, A. B. Author of the Ode to the Warlike Genius of Great-Britain, &c. &c. 2d Edit. 4to. Exeter. Sold by Baldwin and Dodfley. happy, and fhew that Mr. Talker has perufed thofe models of compofition with no common fhare of talte and attention. The marginal references and notes we do not admire. They hurt the eye, by their awkward and uncouth appearance. Why were they not placed at the bottom of the page among their brethren? IN the London Magazine for January laft*, fome account was given of the first edition of this poem. Mr. Talker has now republifhed it, with alterations and additions. The alterations are for the most part verbal, and may be confidered as improvements. The author poffeffes fome portion of genius, but does not appear to fubmit willingly to the lime labor. His rhimes, however, are generally chafte, and his verfification harmonious. But yet the ear is not quite fatisfied. It is neither the jingle of rhime, nor a certain number of fyllables in a line, which conftitutes poetry. Force and comprehenfion in the conception of ideas, elegance and animation in the expreffion of them, and plans well digested, are neceffary requifites. Mr. Tafker's language is not always equally poetical, "The official Household Steward, gay Carlifle" has fcarcely more poetry in it than, "Lieutenant-Colonel to the Earl of Mar" There are other lines of the fame caft, which require correction, and we are rather furprized that they efcaped the ingenious author, while he was employed in revifion. The allufions to the Roman poets, and the claffical imitations interfperfed through this poem, are frequently LOND. MAG. Sept. 1783. The principal addition to this poem, is the paffage in which the Georgium Sidus is mentioned. We fhall tranfcribe it, that our readers may be enabled to form fome judgement for themfelves of the poetical abilities of Mr. Talker. } "O mufe of glory, ceafe thy full career, (Aided by wondrous optic glafs) from far The dim faint fplendours of the GEORGIAN Such is the appearance which Mr. Herfchell's famous difcovery makes in poetical language. An account of I i *Page 39. this +At the time of the first edition, the fate of the Ville de Paris, Glorieux, He&tor, &c. &c. wa not precifely known in England. Mr. Herfchel, by means of a moft curious optic glafs of his own invention, hath difcovered an immenfely-dittant planet, which apparently belongs to cur Solar Syftem; and which is fuppofed to perform its revolution round our fun once in an hundred years. At fuch an inconceivable distance, far beyond Jupiter or Saturn, the thining of this Itar muft appear very faint, even through the me dium of the belt conftructed telescopes, to a fpectator fituated on the furface of the globe of the earth. Mr. Herfchel (from Ho.ace's happy phraie of "Julium Sidus," in compliment to Julius Cæfar) hath named this planet Georgium Sidus, in compliment to his prefent Majetty. this far, and of the opinions of the aftronomers in different parts of Europe, was prefented to our readers, in the Aftronomical department of our last Magazine. To this poem Mr. Tasker has fubjoined a copy of verfes to Dr. Johnfon, of which the thoughts are fometimes vigorous, and the lines generally mufical. The lines on Mr. Barry, the Fainter, which follow, were published in the London Magazine for laft May. The eulogium is well merited by fuch eminent abilities. Those who enjoyed the pleafure of attending Mr. Barry's exhibition will acknowledge the truth of the praife, and thank Mr. Tasker, for recalling to their memory a work which difplayed fo uncommon an exertion of the human powers, and fo wonderful an union of fplendid talents and indefatigable industry. ART. XIX. The Doctrine of Eclipfes, bath folar and lunar; containing short and enly Precepts for computing folar and lunar Eclipfes. The general and geographical Phenomena of folar Eclipfes. The Phenomena of folar Eclipfes for any particular Place, with or without Parallaxes, fully and clearly explained, from the latest Discoveries and Improvements; whereby any Perfon of a moderate Capacity may be able in a fhort Time to folve thefe grand and fublime aftronomical Problems. With correct aftronomical Tables from a manufcript Copy of the Tabule Dunelmenfes, fitted to the Meridian of Greenwich. By Blith Hancock, Teacher of the Mathematics. 8vo. Booth at Norwich. THE contents of this pamphlet are fet forth in the title-page fo fully, that it is unneceffary for us to add a word on the fubject. With refpect to the execution, we have only to fay that there are reafons for thinking the author knows what he is about; but, unfortunately, he expreffes his meaning fo badly, that we fear no other perfon will, who is not, at leaft, as well acquainted with the fubject as himself. The tables are not the Tabulae Dunelmenfes, but a compilation from them; which, for any thing that we know to the contrary, may be as exact, but they ART. XX. Philofophical Tranfactions for the Year 1782, Part II. London. THIS volume contains ten papers, of which fome are on very curious fubjects. We fhall give an account of their contents, in the order which has been affigned them, in this fecond part of the Philofophical Tranfactions for the year 1782. 1. An attempt to make a thermometer for meafuring the higher degrees of heat, from a red heat up to the ftrongeft that veffels made of clay can fupport. By Jofiah Wedgwood. Communicated by Sir J. Banks, Bart. P. R.S. (Read May 9, 1782.) Mr. Wedgwood, formerly the partner, and now the fucceffor, of the late Mr. Bentley, difplays uncommon ingenuity and very extenfive knowledge are not fo convenient for ufe. The merits of the Tabule Dunelmenfes are now well-known to every one who is converfant in thefe fpeculations though tolerably exact, confidering the number of equations that are employed, they are very inferior, in that refpect, to the tables of Mayer and Morris. We cannot conclude this fhort article, without expreffing our aftonishment that the name of Dr. Parr, of Norwich, who, in depth of learning and elegance of tafte, has fo few rivals, fhould be found at the head of the dedication prefixed to this performance. of the Royal Society of London, Vol. LXXII. Davis and Elmiley. in this memorial. He begins with obferving, that "a meafure for the higher degrees of heat, fuch as the common thermometers afford for the lower ones, muft be an important acquifition, both to the philofopher and the practi cal artift." As there are many experiments, in which the precife measure of heat employed has never been afcertained, fuch an inftrument will be of fingular ufe. Many proceffes will be rendered eafy, and their fuccefs certain, which have frequently failed, owing to the difficulty of feizing the moment when there was neither an excefs of heat, nor a deficiency. Mr. Wedgwood tells us, that he has frequently frequently been perplexed, in the experiments which he has made for the improvement of his manufacture, to afcertain the exact degree of heat to which his experiment pieces were expofed. Red, bright red, and white beat, are indeterminate expreffions; and on the measures which the kilns afforded he could not always place dependance. The effects of fire upon fome known body can alone afcertain its force. is well known that it changes colours, It and he obferved that compofitions of calces of iron with clav affumed fuch diftinct colours and fhades, as promifed to afford useful criteria of the refpective degrees. He, therefore, prepared feveral circular pieces of fuch a compofition, about an inch in diameter, and a quarter of an inch thick. Thefe were placed in a kiln heated as uniformly as poifible for fixty hours. At equal intervals thefe pieces were taken out, and piled, in a glafs tube, upon one another, and exhibited rather an extenfive feries of colours; from a flesh colour to a deep brownish red, thence to a chocolate, and fo on to nearly black, with all the intermediate tints. To this tube a back was fixed, and the numbers of the pieces marked upon it refpectively oppofite to them, like the fcale of a thermometer. These numbers resemble thermometric divifions or degrees; fo that if another piece of the fame compofition were heated in any other kiln, not exceeding the utmoft heat of the first, it would acquire a colour correfponding to fome of the pieces in the tube, and point out the degree of heat which that piece has undergone. A thermometer on fuch a principle, Mr. Wedgwood allows is liable to objections. Ideas of colours cannot be communicated by words. The various fhades cannot be equally diftinguished by all eyes, nor by all lights, and may be altered by phlogistic vapours. The diminution of argillaceous bodies by fire, Mr. Wedgwood obferves, is a diftinguishing character of this order of earths, and is a more accurate and extenfive meafure of heat than the different fhades of colour. This 243 66 mea diminution begins in low red heat, and proceeds, as the heat increafes, till the clay is vitrified. The contraction of than one fourth part in every dimenfion. fome good clays is confiderably more fure of fire fufficient for every purpose He then propofes to get a triving to measure the contraction of of experiment or bufinefs, by conly contracted by heat, with eafe and clays, unvitrefcible, and always equalminute accuracy. " tenfity, and meafuring the degrees of The beft clay for fupporting the infire, he found to be the pureft Cornish porcelain clay, which he prepared in the following manner: paffed through a lawn, of which the When the clay is washed over and interftices fhould be less than the 100,000 part of an inch, it must be dried, and put into boxes, to prevent, effects of air and moisture. the for ufe, with about two fifths of its "The dry clay is to be foftened weight of water; and formed into fmall pieces, in little moulds of metal, fix-tenths of an inch in breadth, with the fides pretty exactly parallel, this measured, about four-tenths of an inch being the dimenfion intended to be deep, and one inch long. To make the clay deliver eafily, it will be neceffary to oil the mould, and make it. warm. "Thefe pieces, when perfe&ly dry, gage, confifting only of a bottom, are put into another iron mould or with two fides, five-tenths of an inch deep; to the dimenfions of which fides the breadth of the pieces is to be pared down. which they are to fuffer from the action "For meafuring the diminution of fire, another gage is made of two pieces of brafs, twenty-four inches long, with the fides exactly straight, divided into inches and tenths, fixed five-tenths of an inch afunder at one upon a brafs plate; fo that one of the end, and three-tenths at the other, thermometric pieces, when pared down in the iron gage, will just fit to the wider end. Let us fuppofe this piece to have diminished in the fire one-fifth I i2 of of its bulk, it will then pafs on to half the length of the gage; if diminifhed two-fifths, it will go on to the narrowest end; and in any intermediate degree of contraction, if the piece be flid along till it reft against the converging fides, the degree at which it ftops will be the meafure of its contraction, and confequently of the degree of heat it has undergone." Thefe are the outlines which Mr. Wedgwood gives, as neceflary for making and using this thermometer. He then tells us, that there are inexhauftible mines of this clay in Cornwall; and adds that all the clay employed in thefe thermometers fhould be perfectly fimilar. The qualities of this clay are very accurately defcribed, and rules are laid down, that all thermometers which are made on this principle may be equally affected by heat, though made in different parts of the world, and by different perfons. Rules are then given for the formation of a fcale. Mr. Wedgwood at one time hoped that the gradation of the common thermometer might be continued up to the red heat, at which the fhrinking of the clay commences, fo as to connect the two thermometers together by one feries of numbers; but he found that the lofs of weight was not fufficiently uniform, or proportional to the degree of heat, to anfwer that purpofe. Mr. Wedgwood relates the following fingular properties of thefe thermometers, which render them peculiarly fit for the purposes to which they are applied. "When baked by only moderate degrees of fire, though they are, like other clays, of a porous texture, and imbibe water, yet, when faturated with the water, their bulk continues exactly the fame as in a dry state. By very strong fire they are changed to a porcelain of femi-vitreous texture; nevertheless their contraction, on further augmentations of the heat, proceeds regularly as before, up to the highest degree of fire that I have been able to produce. 66 They bear fudden alternatives of heat and cold; may be dropped at once into intenfe fire, and, when they have received its heat, may be plunged as fuddenly into cold water, without the leaft injury from either. "Even whilft faturated with water in their porous flate, they may be thrown immediately into a white heat, without burtting or fuffering any injury. "Sudden cooling, which alters both the bulk and texture of moft bodies, does not all affect thefe, at least not in any quality fubfervient to their thermometric ufcs. "Nor are they affected by long continuance in, but folely by the degree of heat they are expofed to. In three minutes, or lefs, they are perfectly penetrated by the heat which acts upon them, fo as to receive effect) the full contraction which that degree of heat is capable of producing, equally with thofe which had undergone its action during a gradual increafe of its force for many hours. Strong degrees of heat are communicated to them with more celerity than weak ones: perhaps, the heat may be more readily tranfmitted, in proportion as the texture becomes more compact." After relating the qualities of thefe thermometer pieces, Mr. Wedgwood proceeds thus: "The use and accuracy of this thermometer for meafuring after an operation the degree of heat which the matter has undergone, will be apparent; the foregoing properties afford means of mcafuring it, alfo, cafily andexpeditioufly during the operation, fo that we may know when the fire is encreafed to any degree previously determined upon. The piece may be taken out of the fire in any period of the process, and dropped immediately into water; fo as to be fit for meafuring by the gage in a few feconds of time. At the fame inftant, another piece may be introduced into the place of the former, to be taken out and meafured in its turn; and thus alternately, till the defired degree of heat is obtained. But as the cold piece will be two or three minutes in receiving the full heat, and correfponding contraction; to avoid this lofs of time, it may be proper, on fome occafions, to have two or more pieces, pieces, according to convenience, put in together at first, that they may be fuccellively cooled in water, and the degrees of heat examined at shorter in tervals." Plate glafs Delft ware is fired at Queen's ware at 114° 70 124 40 or 41 86 Stone ware, or Pats du Grès, at 102 These thermometers have enabled the ingenious inventor to afcertain the heats by which many of the porcelains and earthen wares of diftant nations and different ages have been fired. Compofitions in which clay is the principal ingredient fuffer no diminution in bulk, till they are expofed to a greater heat than they underwent originally. Mr. Wedgwood finds, therefore, that the ancient Etrufcan wares appear to have undergone heats from 20° to 32°. Jafper diminishes in fire; granite is enlarged; while flint and quartoze ftones are neither enlarged nor diminished. Thefe experiments were made in fires between 70 and 80° of this thermometer. Mr. Wedgwood informs us, alfo, that the Etrufcan ware melted at 33° 245 about 360 94 105 112 121 Bristol china fhews no vitrification at 135 But the common Chinese porcelain he could not vitrify. It became foft at 120°, and funk down, and applied itfelf close to the irregularities of the furface underneath, at 156°. He could not foften the true ftone Nankeen, nor the Drefden porcelain. Mr. Pott fays, that it is " among the mafter-pieces of art" to melt a mixture of chalk and clay in certain proportions, which from his tables appear to be equal parts. Mr. Wedgwood found that this mixture melted into a perfect glafs at 123°. All experiments may have their refpective degrees of heat afcertained by repeating and accompanying them with thefe thermometric pieces. By thefe means they may be rendered more intelligible and ufeful to the reader, the experimenter, and the working ar tist. By this ingenious difcovery Mr. Wedgwood has opened a field for thermometrical inquiries, which has never been explored. He has enabled mankind to judge with more clearness and precifion about the differences of the degrees of ftrong fire, and their correfponding effects upon natural and artificial bodies. Thefe degrees may now be accurately meafured, and compared with each other, as well as the lower degrees of heat, which are meafurable by the common mercurial ther mometer. This paper is followed by an Appendix, which exhibits an analysis of the clay with which thefe thermometric pieces are formed. concludes from his experiments, that it Mr. Wedgwood is a fubftance of a filiceous kind, becaufe it cannot, from its qualities, belong to any other order of earthy bodies. The clay he proves to confift of two parts of pure filiceous earth to three parts of pure argillaceous or aulminous earth. II. An It is remarkable, that in brafs and copper founderies the workmen carry their fires to 140. |