1 afcended into the atmosphere, the French philofophers juftly concluded, that one filled with inflammable air, which was fo much lighter, muft neceffarily produce a more powerful effect. After many difficulties, fuch a balloon was accordingly constructed at Paris by Meffrs. Roberts, under the fuperintendance of Mr. Charles, profeffor of experimental philofophy. This balloon, the first of the kind, was launched on the 27ft of Auguft, 1783. We have thought proper to follow our author thus far, because we afcertain the dates of thefe difcoveries-Mr. Cavallo then continues his history, with an account of all the voyages that have hitherto been, fucceffively undertaken in different parts; either with rarefied air, or inflammable air balloons, of the fuccefs that has attended them, and of all the circumftances worthy of remark that have occurred in them. The fecond and philofophical part of Mr. Cavallo's work, on the practice of aeroftation, is as the former, divided into chapters-The first of thefe explains in a clear manner the general principles of the art-The fecond treats of inflammable air, and of the feveral combinations and proceffes by which it may be produced, for the purpose of filling balloons-Iron, tin, and zinc, either with the vitriolic or the marine acid diluted, yield plenty of this air; but tin and the marine acid being dearer than the other fubftances, iron and zinc, with the vitriolic acid diluted, have been the materials moftly used. A computation is made of the quantity of inflammable air collected from these several substances, of which iron yields more than zinc. Inflammable air may likewife be obtained at a cheaper rate, from the action of fire on various fubftances, and although this be not fo light, as that which is acquired by the effervescence of acids with metallic bodies, yet Mr. Cavallo thinks it may fuperceed the use of them in the construction of balloons on account of the comparative cheapness of the procefs. Pitcoal is the fubftance recommended by Mr. Cavallo, as furnishing the greateft quantity at the cheapest rate-But thefe modes are all likely to give way to the method of obtaining inflammable air lately discovered by Mr. Lavoifier, and examined by Dr. Prieftly, when the operation is reduced to a greater certainty. This method confifts in filling iron or copper tubes with iron turnings, making part of them red hot, and then fending the vapour of boiling water through them, Iron is faid to yield one half more of inflammable air by this procefs than by the action of the vitriolic acid. In In the third chapter, Mr. Cavallo speaks of the figure and capacity of aeroftatic machines, of the materials proper for the conftructing, and of the mode of preparing those materials. The author here gives plain arithmetical calculations for determining the powers of a balloon in proportion to its fize, and the number of yards of filk or linen neceffary to construct one of a given diameter. He defcribes the difference to be observed in constructing the balloon with rarefied air,and that with inflammable air; and the apparatus neceffary to be fixt to them for the purpose of afcenfion, together with the mode of faftening that apparatus. Mr. Cavallo then takes notice of the various means used or propofed for the purpose of raising, or lowering these machines, and likewife for directing them. For the last purpose, oars and wings have been the only modes hitherto ufed with any apparent degree of fuccefs, and these our author thinks may be capable of confiderable improvement, though perhaps never fo as to produce any great effect, efpecially when the machine travels at a great rate. In the fifth chapter the manner of filling large balloons is exemplified, and the feveral things wanting or useful in an aerial voyage, are enumerated. The fixth chapter, on the experiments and obfervations proper to be made in the course of an aerial voyage, is a very important one. It explains the mode of determining the height of the balloon by the barometer, compared with the thermometer; and likewife the geometrical method, of settling this altitude, which is done by the aerial traveller himfelf, obferving by means of a fextant or quadrant the angle which the horizon fubtends. The laft chapter enumerates the ufes to which aeroftation may be applied. The work would have been incomplete' without it, though the author profeffes only to mention the most obvious ufes, which muft of courfe contain nothing new. Such are the general contents of Mr. Cavallo's work, the first part of which furnishes us with entertainment, and with that fort of information, which we could not wish to fee more agreeably collected together; the latter part contains ufeful inftructions, very fit for the perufal and attention of. those who are defirous of purfuing or undertaking this new and fingular method of travelling. ART. X. Inftitutions of Medicine. Part I. Phyfiology. For the ufe of Students in the Univerfity of Edinburgh. By William Cullen, M. D. &c. 3d Edition corrected. 8vo. 4s. boards. Elliot, Edinburgh. Cadell. London. N this edition there is nothing new, except a few verbal ment at a more complete publication at fome future period, which we fincerely with him leifure and health to accomplish. But though the author did not choose to add any recommendation of novelty to his work, the publisher forefeeing in his prudence, that fomething of this kind would be neceffary, has contrived, by communicating to the feveral paragraphs a mutual repulfion, to dilate a 12mo. into an 8vo. and by confequence to enlarge the price in proportion. This art has been advancing towards perfection with hafty ftrides of late years; but it has notwithstanding happened in most cafes, that the editions have diminished in bulk and price, as they have increased in number, unless fome confiderable addition has been made to the republished work. We must therefore confider the prefent attempt as one of the greatest modern improvements; and we doubt not but it will engage the notice and approbation of those whom it may concern. The fame author has juft published a new edition of his excellent and ufeful work, the Synopfis Nofologiæ Méthodicæ. The additions to the first volume are taken from Dr. Macbride's Introduction. In the fecond volume which contains the authors own arrangement and difinitions there are a few, but very few alterations. Dr Cullen is alfo employed about a work ftill perhaps more interefting, a correct edition of his Materia Medica. However imperfect the furreptitious copy was, and though the fenfe of the author was in many parts mifreprefented, it was yet fought with great avidity by the medical student; nor can any publication be more acceptable than a perfect edition, which we hope will foon appear. ART. XI. J. Brunonis, M. D. De Medicina Prælectoris &c. IN what refpects this differs from the former edition we cannot pretend to fay. The brevity and improper ftyle of that edition foon obliged us to defift from the perufal; we have heard that there is lefs affectation and obfcurity in the language of the prefent. Whether it contains any further lights lights, we cannot therefore determine. That the reader, who has not yet heard of this new doctrine, may form fome idea of what he is to expect, we fhall tranflate the author's own fummary of it. After having obferved that catarrh does not, as is commonly imagined, derive its origin from cold, but from heat and other ftimulants, and that it is to be cured by cold and other debilitating means, he fubjoins, I have divided all common difeafes into two forms, the phlogistic or fthenic, and the afthenic or antiphlogistic, of which the former confifts in too great excitement, the latter in too little, the one is removed by debilitating, the other by ftimulating means, &c." He concludes his preface by asking, whether a conjectural, inconfiftent, and in most of its parts falfe art, is at last reduced to a certain fcience, which may be called the science of life? This weighty question we shall leave to the decifion of those who may chufe to confider it. ART. XII. Reflections on the prefent Matters in Difpute between Great Britain and Ireland; and, on the Means of converting thefe Articles into mutual Benefit for both Kingdoms. By Jofiah Tucker, D. D. Dean of Gloucefter. 8vo. IS. Cadell. London. UB PON the principle of the Independency of Ireland, Dr. Tucker argues its title to a free trade to every foreign country; and he is ftrenuous to fhow, that the free exercise of trade by the Irish, would neceffarily be attended with advantages highly beneficial to England. In the view of the extenfion of the Irish trade to countries beyond the Cape of Good Hope, he contends, that the English, emancipating themselves from a pernicious monoply, would be zealous to fit out fhips from the ports of Ireland to trade to the Eaft under the fanction of the Irish flag. Now, in confequence of the importation ofthe produce of the Eaft to Ireland, he conceives that the manufactures of England would advance in profperity. For it would follow, that the raw filk, the cotton, the wool, and the other articles neceffary in many different branches of labour would fall in their value; as the Eaft-India Company could no longer affix what price it pleafed upon its imports. Similar advantages upon this way of reasoning would alfo, in the opinion of our author, be derived to England from the extenfion of the Irish trade to Egypt, the Archipe-1 lago, and the Levant. Proceeding in his fubject, he lays it down as another advantage of opening an unrestrained trade to Ireland, that it would operate a free importation of fugars, and of other products of the warmer climates from the cheapest market; and that, by that means, a foun dation would be laid for the gradual abolition of the prefent inhuman flave-trade. The creation of a free navigation is an additional advantage which our author deduces from the full extenfion of the Irish trade; and here, he endeavours to combat the clogs and reftrictions which are required by the famous Navigation A&t. And laftly he regards it as a fource of emolument to arife out of the freedom of the Irish trade, that there would prevail, for the benefit of both kingdoms, an unrestricted exportation and importation of grain. Upon these different topics Dr. Tucker expreffes himself with much ingenuity, and on his part with entire decifion. His performance, accordingly, may be useful; and it will doubtless have the effect to carry the attention of merchants and politicians to the minute examination of matters which are of the highest importance. But it is certainly obvious, that our author, notwithstanding his abilities, has neglected to enter into any inveftigation of that multiplicity of circumftances, and that variety of views which are abfolutely neceffary for the full difcuffion of the fubject he has undertaken. His pamphlet contains only hints, which, however plaufible they may appear, muft not be fuppofed to be incontrovertible. His zeal, however, as a good citizen deferves applaufe; for we are willing to believe, that he acts under the influence of public virtue and patriotism. In an Appendix to his Reflections, our author, having regretted that academical ftudies, have, in general, fo flight a tendency to inftruct the rifing generation in the civil, political, and commercial interefts of their own country, proposes that fubjects of this kind, under the allurement of premiums, fhould be offered to the graduate students of the univerfities of England and Scotland. This fcheme, though it is patriotic, he propofes with a diffidence that is not natural to him; and, indeed, to us it appears to be highly vifionary. It would, furely, redound more to the interefts of the kingdom, if foundations fhould be made for able teachers to prelect on thefe topics in our univerfities. As a fpecimen of the manner and way of thinking of our author, we fhall fubmit to our readers what he has advanced concerning the Act of Navigation. The precife idea of a monopoly is this, that it is a privilege, or exclufive charter granted to ferve a few, at the expence, and to the detriment of the many. According to this definition, it is impoffible that that famous monopoly, called the Act of Navigation, can be vindicated on the footing of commercial utility. National prejudices, indeed, are frongly in its favour; but prejudice and reafon are not always the fame thing; and it doth not follow that nations, any |