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ascended into the atmosphere, the French philosophers juftly concluded, that one filled with infiammable air, which was so much lighter, muft necessarily produce a more powerful effect. After many difficulties, such a balloon was accord ingly constructed at Paris by Messrs. Roberts, under the superintendance of Mr. Charles, professor of experimental philosophy. This balloon, the first of the kind, was launched on the 27ft of August, 1783

We have thought proper to follow our author thus far, because we ascertain the dates of these discoveries-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 success that has attended them, and of all the circumstances worthy of remark that have occurred in them.

The second and philosophical part of Mr. Cavallo's work, on the practice of aeroftation, is as the former, divided into chapters—The first of these explains in a clear manner the general principles of the art—The second treats of inflammable air, and of the several combinations and processes 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 substances, iron and zinc, with the vitriolic acid diluted, have been the materials mostly used. A computation is made of the quantity of inflammable air collected from these several substances, of which iron yields more thanzinc.

Inflammable air may likewise be obtained at a cheaper rate, from the action of fire on various substances, and al. though this be not so light, as that which is acquired by the effervescence of acids with metallic bodies, yet Mr. Cavallo thinks it may superceed the use of them in the construction of balloons on account of the comparative cheapness of the process. Pitcoal is the substance recommended by Mr. Cavallo, as furnishing the greatest quantity at the cheapest rate-But these modes are all likely to give way to the method of obtaining inflammable air lately discovered by Mr. Lavoisier, and examined by Dr. Priestly, 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 sending the vapour of boiling water through them, Iron is said to yield one half more of inflammable air by this process than by the action of the vitriolic acid.

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In the third chapter, Mr. Cavallo speaks of the figure and capacity of aeroftatic machines, of the materials proper for the constructing, 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 necessary to construct one of a given diameter. He describes the difference to be observed in constructing the balloon with rarefied air,and that with inflammable air; and the apparatus necessary to be fixt to them for the purpose of afcenfion, together with the mode of fastening that apparatus.

Mr. Cavallo then takes notice of the various nieans used or proposed for the purpose of raising, or lowering these machines, and likewise for directing them. For the last purpose, oars and wings have been the only modes hitherto used with any apparent degree of success, and these our author thinks may be capable of considerable improvement, though perhaps never so as to produce any great effect, especially when the machine travels at a great rate:

In the fifth chapter the manner of filling large balloons is exemplified, and the several things wanting or useful in an aerial voyage, are enumerated.

The fíxth chapter, on the experiments and observations 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 likewise the geometrical method, of settling this altitude, which is done by the aerial traveller him. felf, observing by means of a sextant or quadrant the angle which the horizon fubtends.

The last chapter enumerates the uses to which aerostation may be applied. The work would have been incomplete without it, though the author professes only to mention the most obvious uses, which must of course contain nothing

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Such are the general contents of Mr. Cavallo's work, the first part of which furnishes us with entertainment, and with that sort of information, which we could not wish to see more agreeably collected together; the latter part contains useful inftructions, very fit for the perufal and attention of . those who are desirous of pursuing or undertaking this new and fingular method of travelling.

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Art. X. Inftitutions of Medicine. Part I. Phyfiology. For the

use of Students in the University of Edinburgh. By William Cullen, M. D. &c. 3d Edition corrected. 8vo. 45. boards.

Elliot, Edinburgh. Cadell. London. I N this edition there is nothing new, except a few verbal

alterations. The author feems to hint in the advertisement at a more coinplete publication at some future period, which we fincerely with him leisure 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 necessary, has contrived, by communicating to the several paragraphs a mutual repulsion, to dilate a 12mo. into an 8vo. and by consequence to enlarge the price in proportion. This art has been advancing towards perfection with hatty strides of late years; but it has notwithstanding happened in most cases, that the editions have diminished in bulk and price, as they have increased in number, unless some considerable addition has been made to the republished work. We must therefore consider the present 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 same author has juft published a new edition of his excellent and useful work, the Synopsis Nosologiæ Methodicæ. The additions to the first volume are taken from Dr. Macbride's Introduction. In the second volume which contains the authors own arrangement and difinitions there are a few, but very few alterations.

Dr Cullen is also employed about a work ftill perhaps more interesting, a correct edition of his Materia Medica. However imperfect the furreptitious copy was, and thoughi the sense of the author was in many parts misrepresented, it was yet sought with great avidity by the medical student; nor can any publication be more acceptable than a perfect edition, which we hope will soon appear.

ART. XI. 7. Brunonis, M. D. De Medicina Præle&oris &c.

Elementa Medicinæ. Editio altera. Edinburgi. Elements of Medicine. By J. Brown, M. D. 8vo. 2 Vols. 8s.

boards. Printed for the Author. IN N what respects this differs from the former edition we

cannot pretend to say. The brevity and improper style of that edition foon obliged us to defiit from the perusal; we have leard that there is less affectation and obfcurity in the ja!guage of the present. 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 some idea of what he is to expect, we shall translate the author's own summary of it. After having observed that catarrh does not, as is commonly imagined, derive its origin from cold, but from heat and other stimulants, and that it is to be cured by cold and other debilitating means, he subjoins, Do I have divided all common diseases into two forms, the phlogistic or sthenic, and the asthenic or antiphlogistic, of which the former consists in too great excitement, the latter in too little, the one is removed by debilitating, the other by Itimulating means, &c.” He concludes his preface by asking, whether a conjectural, inconsistent, and in most of its parts false art, is at last reduced to a certain science, which may be called the science of life? This weighty question we shall leave to the decision of those who may chiuse to consider it.

IS.

UD

Art. XII. Reflections on the present Matters in Dispute between Great

Britain and Ireland; and, or the Means of converting these Articles into mutral Benefit for both Kingdoms. By Jofiah Tucker, D. D. Dean of Gloucester. 8vo. Cadell. London.

PON the principle of the Independency of Ireland,

Dr. Tucker argues its title to a free trade to every fo. reign country; and he is ftrenuous to show, that the free exercise of trade by the Irish, would neceffarily be attended with advantages highly beneficial to England. In the view of the extension 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 but ships from the ports of Ireland to trade to the Eatt under the sanction of the Irish flag. Now, in consequence of the importation of the produce of the East to Ireland, he conceives that the manufa&tures of England would advance in prosperity. For it would follow, that the raw silk, the cotton, the wool, and the other articles necessary in many different branches of labour would fall in their value ; as the East-India Coinpany could no longer affix what price it pleased upon its imports.

Similar advantages upon this way of reasoning would also, in the opinion of our author, be derived to England from the extension of the Irish trade to Egypt, the Archipe.' lago, and the Levant. Proceeding in his subject, he lays it down as another advantage of opening an unrestrained trade to Ireland, that it would operate a free importation of sugars, and of other products of the warmer climates from the cheapest market; and that, by that means, a foun'A a 2

dation

dation would be laid for the gradual abolition of the present inhuman flave-trade.

The creation of a free navigation is an additional advantage which our author deduces from the full extension of the Irish trade ; and here, he endeavours to combat the clogs and restrictions which are required by the famous Navigation A&. And lastly he regards it as a source 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 investigation of that multiplicity of circumftances, and that variety of views which are absolutely neceffary for the full discussion of the subject he has undertaken. His pamphlet contains only hints, which, however plausible they may appear, must not be supposed to be in. controvertible. His zeal, however, as a good citizen deserves applause ; for we are willing to believe, that he acts under the influence of public virtuc and patriotism.

In an Appendix to his Reflections, our author, having regretted that academical studies, have, in general, so flight a tendency to instruct the rising generation in the civil, political, and commercial interests of their own country, proposes that subjects of this kind, under the allurement of premiums, should be offered to the graduate students of the universities of England and Scotland. This scheme, though it is patriotic, he proposes with a diffidence that is not natural to him: and, indeed, to us it appears to be highly visionary. It would, surely, redound more to the interests of the kingdom, if foundations should be made for able teachers to prelect on these topics in our universities.

As a specimen of the manner and way of thinking of our author, we shall submit to our readers what he has advanced concerning the Act of Navigation.

• The precise idea of a monopoly is this, that it is a privilege, or exclusive charter granted to serve a few, at the expence, and to the detriment of the many. According to this definition, it is impossible that that famous monopoly, called the Act of Navigation, can be vindicated on the footing of commercial utility. National prejudices, indeed, are ftrongly in its favour ; but prejudice and reason are not always the same thing; and it doth not follow that nations, any

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