jects affords. Dr. Waring's labours in analytics are well known ; of thefe a Paper* appeared, in the Tranfactions of 1784, on the Summation of Series, in which is given a method of finding the fum of a feries whofe general term (P2, a fraction reduced to its loweft terms) is a determinate algebraical function of the quantity (Z), the distance from the first term of the feries. The Doctor's prefent performance is of a fimilar kind with the former, and fhews how the methods there exhibited may be applied or extended to several cafes not enumerated before.

In the fecond part of this Paper Dr. Waring confiders the feveral methods for approximating the value of quantities, whofe exact value could not be obtained by any other means. The reader will here meet with many ufeful methods of refolving equations of higher exponents, together with observations on the writings of former analyfts.. Much has been advanced on this fubject; the prefent labours of Dr. Waring are rather illuftrations of the algebraical inquiries of preceding authors, than any new improvements of the art.

The third part contains fome obfervations in order to deter

mine the cafes in which the feries for finding the fluent of axx,

or the area of a curve whofe ordinate is ax" and abfciffa x, converges or diverges; this is a useful inquiry, because the feries is of no use if it diverges, and of very little except the convergency is quick. We cannot lay the particulars of this long Paper before our Readers: the above account will inform them what it chiefly concerns, and what parts of the extenfive fubjects of infinites the Doctor has here elucidated.

Art. 9. Obfervations and Remarks on thofe Stars which the Aftrenomers of the laft Century fufpected to be changeable. By Edward Pigott, Efq.

In this Paper Mr. Pigott has given a catalogue of fuch fixed ftars as have been obferved to be variable in fize and luftre, and alfo fuch as are fufpected, from the accounts of former aftronomers, to be fo. The catalogue contains 50 fixed ftars, with their right afcenfion and declination reduced to the beginning of the year 1786. Mr. Pigott then enumerates the particular obfervations on each of thefe ftars, and the reafons why he fuppofes fome of them variable, although their changes have not yet been ascertained.

The eftablishing of facts is the firft ftep toward the advancement of science; and though thefe difcoveries do not feem to be of any real ufe at prefent, yet they may, at fome future period, throw fresh light on aftronomy. The caufes of the appearances

*For an account of which, fee Rev, vol. lxxiii. p. 197.

are

are undoubtedly a juft object of inquiry; what has been conjectured concerning them wants as yet much confirmation.

(The Philofophical and Chemical Papers in this Part*, as foon as poffible.)

* N. B. The 2d Part of vol. lxxvi. is just published.

R-m

ART. VI. Chemical Effays. By R. Watfon, D.D. F. R. S. and Regius Profeffor of Divinity in the University of Cambridge. Vol. IV. 12mo. 4s. fewed. Cadell, &c. 1786.

WE

E are forry to find that this is the laft chemical performance we have to expect from the right reverend author. Though convinced, by the uncommon fale of the former volumes, that they met with general approbation, and that they have contributed greatly to the promotion of chemical knowledge, he now refigns, for ever, thefe pleafing and useful purfuits; but not without fingular reluctance, and doing violence to his own feelings. Above two thoufand copies' (he fays) of the former volumes of my Chemical Effays have been fold in lefs than five years. I mention not this circumftance out of vanity, or as if I thought it contained any proof of their merit; but I produce it as a folid proof of the difpofition of the Public to become acquainted with chemical fubjects when they are treated in a popular way. This difpofition has been long prevalent in foreign countries; it seems to be gaining ground in our own; and if I have endeavoured to contribute a little towards its eftablishment amongst us, I hope the utility of the defign will plead my excufe with thofe, who, in the feverity of their judgments, may think that I have contributed more than, from the nature of my profeffion and fituation, I ought to have done.

• When I was elected Profeffor of Divinity in 1771, I determined to abandon for ever the study of chemistry; and I did abandon it for several years: but the veteris veftigia flammæ— ftill continued to delight me, and at length feduced me from my purpose. When I was made a Bishop, in 1782, I again determined to quit my favourite purfuit; the volume which I now offer to the Public is a fad proof of the imbecility of my refolution. I have on this day, however, offered a facrifice to other people's notions, I confefs, rather than to my own opinion of epifcopal decorum-I have deftroyed all my chemical manufcripts. A profpect of returning health might have perfuaded me to purfue this delightful fcience; but I have now certainly done with it for ever; at least I have taken the most effectual step I could to wean myself from an attachment to it, for with the holy zeal of the idolaters of old, who had been addicted to curious arts, I have burned my books!

The

The remainder of the Preface, about 15 pages, is employed in recommending an inftitution at our univerfities, for inftructing young men of rank and fortune in the elements of agriculture; in the principles of commerce; and in the knowledge of our manufactures. This kind of ftudy, the Author obferves, would agreeably folicit, and might probably fecure, the attention of that part of our youth, which, in being exempted from the difcipline of fcholaftic exercises, has abundant leifure for other pursuits; which, in being born to opulence, is unhappily deprived of one of the ftrongest incentives to intellectual exertion,-narrowness of fortune it would prepare them for becoming intelligent legislators of their country; and it would inspire them with fuch a tafte for husbandry, as might conftitute the chief felicity of their future lives.

His notion of national ftrength, fecurity, and happiness, tends not fo much to the extending of our commerce, or increasing the number of our manufacturers, as to the multiplication of an hardy, and, comparatively speaking, innocent race of peasants, by making corn to grow on millions of acres of land where none has grown before. Let us but once have as many Britons in the kingdom, as the well-cultivated lands of Great Britain are able to fupport (at least twice the prefent number), and we fhall have little to regret in the lofs of America; nothing to apprehend from the partitioning policy of all the continental defpots in Europe. In thus fixing the bafis of our ftrength on the improved cultivation of our lands, he does not mean to exclude manufactures, but on the contrary, confiders agriculture and manufactures as mutually fubfervient to each other. With regard to commerce, he thinks the prefent ftate of the finance of this kingdom requires it to be cherished with fingular indulgence; and that we shall not fufficiently avail ourselves of the inestimable advantages of our infular fituation, if we do not confider our glory and our fafety as closely connected with the number of our feamen, which will ever be in proportion to the extent of our foreign and domeftic commerce. Perhaps the advantages of com merce, and of manufactures as its bafis, are here eftimated below their real value to the national ftrength and importance; nevertheless, the observations refpecting the education of young men of fortune are certainly juft, and deferve the most serious attention.

The effays which compofe this volume are written on the fame plan as thofe of the three preceding; not with a view to enrich science with any confiderable new difcoveries, but to promote a general tafte for these useful ftudies, and to engage the attention of those who are but little acquainted with chemical fubjects, by defcribing, in a clear and pleafing manner, the fucceffive difcoveries made in fome of the principal branches of chemical knowledge, and the confequent improvements in the arts depending on them. The fubjects are, fubjects

REV. Jan. 1787.

Effay

Effay I. Lapis calaminaris, blende, zinc, brass; containing the natural hiftory of the two firft-mentioned fubftances, the hiftory of the discovery of their being ores of zinc, the methods of extracting zinc from them, the preparation of them for the brassmaker, the manufacture and commerce of brass, &c.

II. On Orichalcum; an enquiry into the orichalcum of the ancients; from which it appears, that the art of making brass was known to the Romans, but was derived to them from fome other country; that brafs was made, in the most remote ages, in India and other parts of Afia, of copper and calamine, as at prefent; and that in the early ages, when iron was little known, it was valued higher than gold *.

III. Of gun metal, ftatuary-metal, bell-metal, pot-metal, and Speculum metal. The compactness of a mixture of copper and tin, which adapts it for making fpeculums, is attributed, with great probability, to the thinness of its fufion. I have obferved' (fays the Author) at Sheffield, that the fame weight of melted feel will fill the fame mould to a greater or lefs height, according to the degree of fufion the fteel has been in; if it has been in a ftrong heat and thin fufion, the bar of caft fteel will be an inch in thirty-fix fhorter than when the fufion has been lefs perfect. On breaking one of the bars made from steel in an imperfect fufion, its infide was full of blebs; a fhorter bar of the fame weight and diameter, which had been in a thin fufion, was of a closer texture.'

IV. Of tinning copper, tin, pewter.

V. Of tinning iron. Plating and gilding copper.

VI. Of gilding in or moulu. Of the ufe of quickfilver in extracting gold and filver from earths. Boerhaave's experiments on quickfilver. Silvering looking-glaffes; and of the time when that art was difcovered. Though this art is commonly fuppofed to be of modern difcovery, we here find it to have been known, probably in the firft century, and with certainty in the fecond. A paffage in Pliny gives good ground to believe that it had been difcovered before his time, by the Sidonians.

VII. Of the tranfmutability of water into earth. The facts and arguments on both fides are stated, but the point is left undetermined.

VIII. Of Weftmoreland flate, and fome other forts of ftones. From a particular examination of the gravities of different forts of the flate, and a comparifon with lead and copper as used for covering buildings, it is concluded that 42 fquare yards will be covered by 4 hundred weight of copper, 26 of fine flate, 27 of lead, 36 of coarfer flate, and 54 of tile. By ftrong fire, the flate was reduced into a black cellular glafs, fo hard as to ftrike

*This Effay is fimilar to that in the Manchefter Tranfactions; fee our Rev. for Oct. last, p. 252.

fire with fteel. Very good glafs, the Author obferves, might probably be made from the late alone, for the cellular texture would difappear by continuance of fire; but certainly it might be made from the flate mixed with fern afhes, or with kelp afhes, or with other fubftances containing fixed alcali.' We hope, with the Bishop, that this hint will not be given in vain; and we beg leave to hint alfo, that if the certainty of vitrification with alcalies has been only inferred from the known effect of thofe falts upon fome other earthy bodies, fuch conclufion cannot be depended on. There are earthy compounds, fufible by themselves, which refufe to unite with alcalies: we have mixed vitrefcible stone with glafs itself, and found the vitrification impeded, and the alcali of the glafs fpued out. Whether the Weftmoreland flate is, or is not, of this nature, can be ascertained only by trial; but, in either cafe, we perfuade ourselves that the candid Author will be rather pleafed, than offended, with our remark.

To this volume is added a very useful appendage, a general Index to all the four. Chi-e

ART. VII. A Syftem of Surgery. By Benjamin Bell, Member of the Royal College of Surgeons, one of the Surgeons to the Royal Infirmary, and Fellow of the Royal Society of Edinburgh. Vols. III. and IV. 8vo. 12s. Boards. Illuftrated with Copperplates. Elliot, Edinburgh; Robinfons, London. 1786.

HE continuation of this ufeful work, fully fupports and confirms the reputation Mr. Bell had acquired by the two preceding volumes.

The third volume contains, in the former part of it, the theory and practice in affections of the brain from external violence. The very intricate nature of these diforders has excited the attention of practitioners from the time of Hippocrates downward; but although fome material improvements have been introduced into this branch of practice, by the induftry and obfervations of modern Surgeons, yet whoever is accustomed to the treatment of thefe complaints, muft allow that our knowledge of them is ftill very deficient. Our Author, fenfible of the great difficul ties of attaining a certain knowledge concerning the nature and treatment of them, points out the means beft calculated to extricate this part of practice from fuch uncertainty; but before he proceeds to do fo, he gives a concife anatomical description of thofe parts which are more apt to fuffer from injuries done to the head.

Mr. Bell confiders all the fymptoms of difeafes of the brain from external violence, to originate from one of these three circumftances, from compreffion of the brain, from commotion or concuffion, or from inflammation.' Of these he treats in