were neceffary to fave the detachments, that were posted on the hore; and marched at the head of them through a crowd of favages, whofe looks expreffed hoftility and refentment. In their paffage through a village they found a part of the clothes of their flaughtered companions, and a human thigh which had been half devoured.

After discovering fome other islands in the South-Sea our furviving travellers returned to Guam, the largest of the Marianne islands, where M. Tobias, the Spanish Governor, had been active in the introduction of agriculture and other European arts. M. Crozet gives, in the work before us, a circumstantial and accurate defcription of this ifland, and particularly of that beautiful and useful tree, called the Rima, whofe fruit has exactly the taste of our bread, though fuperior to it in a certain delicious freshness, and is fufficient for the nourishment of the inhabitants. This tree was tranfplanted into the ifle of France, by M. Poivre, who has also transplanted several trees and fhrubs from the spiceiflands of the Dutch.

The voyage of Surville, whofe violent proceedings may be confidered as the caufe of Marion's death, and have contributed to render the Europeans odious in these parts of the world, is fubjoined to this work. It contains, in about forty pages, an account of the voyage of this able, intrepid, and turbulent navigator, to the ifles of Bafchy, which lie north-eaft of the Phillippines to New-Zealand, and over the Pacific ocean to the coafts of Peru, where he perished in an attempt to pass the bar of Chilia in his canoe. These voyages, which are certainly adapted to add new improvements to geography, would have answered more effectually that important purpose, if the navigators had employed marine clocks to fix the longitudes.

ART. VIII.

Defeription des Experiences de la Machine Aerofiatique; i. e. Defcription of Experiments made with the Aeroflatic Machine, invented by Meffis. De MONTGOLFIER, &c. By M. FAUJAS DE ST. FOND. 8vo. Paris. 1783.

W

E avail ourselves of the opportunity of this recent publication, to lay before our readers a brief, hiftorical account of the very interefting difcovery which has of late attracted the notice of the whole philofophical world; and which our fanguine neighbours did not fcruple, at the very firft, to dignify with the name of Aerial Navigation.

Although the Author of this book be known to have warmly. efpoufed the party of Montgolfier, in oppofition to that of Charles (for there are parties even concerning Balloons), yet his reputation, as a man of learning and veracity, is fufficiently eftablished, and the facts he here alleges are in general, as we

have had opportunities to afcertain by collateral evidence, stated with fufficient accuracy to juftify us in taking him for our guide in this narrative.

The Preface contains a fhort furvey of what projects have formerly been fuggefted for the purpofe of floating heavy bodies in the atmosphere; the principal of which are thofe of Lana, a Jefuit of Brefcia, and of Galien, a Dominican of Avignon, both which however were, upon well established principles, found by theory to be impoffible in the execution. Due honour is paid to Mr. Cavallo of London, who, in 1782, feemingly with a view to this difcovery, tried to fill bags of paper and bladders with inflammable air; but failed in his attempts, by the unexpected permeability of paper to inflammable air, and the too great proportional weight of the common fized bladders. Had he then thought of employing gummed filk, or gold-beater's fkin, he probably would have plucked. the very laurels that now adorn the brows of Montgolfier and Charles.

I. The honour of the difcovery is certainly due to the brothers STEPHEN and JOSEPH MONTGOLFIER, proprietors of a confiderable paper manufacture at Annonay, a town in the Vivarais, about thirty-fix miles fouth of Lyons: and their invention is. the more to be admired, as it is not the effect of the late difcovery of a permanent elaftic fluid lighter than the common air, but of properties of matter long known, and in the hands of the many acute philofophers of this and of the laft century. They conceived that the effect they looked for might be obtained by confining vapours lighter than common air, in an inverted bag, or covering, fufficiently compact to prevent their evaporation, and fo light, that when inflated, its own weight, added to that of the inclofed vapour, might fall fomewhat short of the weight of the air which its bulk difplaces.

On thefe principles, they prepared matters for an experiment. They formed a bag, or balloon, of linen cloth, lined with paper, nearly spherical, and measuring about 35 feet in diametert, its folid contents were about 22,000 cubic feet, a space nearly equal to that occupied by 1980 lb. of common air, of a mean temperature, on the level of the fea.-The Vapour, which, by conjecture, was about half as light as common air, weighed 990 lb. The balloon, together with a wooden frame fufpended

*The impoflibility of Lana's project was demonftrated by Hook; fee his Philofophical Collections, No. I. p. 28. And fince by Leibnitz. Galien's never needed any confutation.

+ All the meafures here given are French. The French foot is to the English as 141 to 135; a French toife is fix French feet, or, fix and three-eighths English feet.

to

to the bottom, which was to ferve as ballaft, weighed 490 lb. whence it appears that the whole must have been about 500 lb. lighter than an equal bulk of common air. This difference of fpecific gravity, by which thefe bodies are made to rife, we fhall henceforth, without warranting the propriety of the expreffion, call their power of afcenfion.

The 5th of June 1783, was fixed on for the display of this fingular experiment. The States of Vivarais, who were then affembled at Annonay, were invited to the exhibition.-The flaccid bag was fufpended on a pole 35 feet high; straw and chopped wool were burnt under the opening at the bottom; the vapour, or rather smoke, fcon inflated the bag, so as to diftend it in all its parts; and, on a fudden, this immense mass afcended in the air with fuch a velocity, that in less than ten minutes it appeared to be about 1000 toifes above the heads of the spectators. A breeze carried it about 1200 toifes from the fpot whence it departed; and then the vapour, either efcaping through fome loop-holes that had been accidentally left in the conftruction, or being condenfed by the coldness of the circumambient air, the globe defcended gradually on a vineyard, with fo little preffure, that none of the stakes were broken, and scarce any of the branches of the vines bent.

II. The rumour of this fuccefsful experiment foon reached. the metropolis, and rouzed the emulation of the Parifian philofophers. Without waiting for particular inftructions from the inventors, they reflected on a method of their own; and refolved, inftead of vapour, to ufe inflammable air; the fpecific weight of which, when pure, they knew to be to that of common air nearly as ten to one *.

The process of producing this air being very expensive, the Author of the book now before us, fet on foot a fubfcription; and having foon raised a fufficient fum, M. CHARLES, Profeffor of Experimental Philosophy, and M. ROBERT, a mathe matical inftrument-maker, were set to work: and they conftructed a globe of lutefiring (taffetas), glazed over with elaftic gum diffolved in fome kind of fpirit or effential oil. After many difficulties and difappointments, which will ever attend firft effays, they fucceeded, in two days, to fill this globe with inflammable air, produced from 1000 lb. of iron-filings and 498 lb. of vitriolic acid, diluted in four times its quantity of water. This globe measured 12 feet 2 inches in diameter,

In juftice to our country, we muft here at least commemorate the name of Cavendish; to whom, it is acknowledged on all hands, the discovery of the fpecific gravity of inflammable air, as well as of many other of its properties, is folely due. See Phil. Trans. Vol. LVI. p. 150.

its folid contents were 943 feet 6 lines cubic, and its power of afcenfion was found equal to 35 lb.

The 27th of August 1783, having been fixed on for the exhibition of this experiment, the balloon was conveyed, in the preceding night, floating in the air, from a court near the Place des Victoires, where it had been conftructed, to the Champ de Mars.Our Author indulges his lively imagination in a lofty description of this nocturnal proceffion, which, he says, moved along in the dead of night, attended by a party of guards, with lighted torches, and feemed fo awful, that the hackney coachmen who happened to be in its way, defcended from their seats, and devoutly proftrated themselves before the fupernatural being that advanced in fuch folemn ftate.

The concourfe of people, on foot and in carriages, was fo immenfe in the Champ de Mar, that a large body of troops were drawn out to prevent disturbances. At five o'clock in the afternoon, a fignal having been given by the firing of a mortar, the cords that confined the globe were cut, and it rofe, in lefs than two minutes, to a height of near 500 toises.-It there entered a cloud, but foon appeared again, afcending to a much greater height; and at laft it was loft among other clouds.

Our Author justly cenfures the conduct of this experiment; obferving, that too much inflammable air, and that even fome common air had been introduced into the globe, which being closed on all fides, left no room for the expanfion of this elaftic fluid when it fhould arrive to a more rarefied medium. We find, in fact, that it must have burft in confequence of this expanfion; fince, after having floated about three quarters of an hour, it fell in a field near Goneffe, a village about five leagues (15 miles) N. N. W. of the Champs de Mars. It muft be allowed, that the mere evaporation of the air could not well have been the cause of its defcending fo foon. Many periodical papers have already entertained the Public with ludicrous accounts of the aftonishment of the peasants who found it, and of the rough treatment it received at their hands.

III. It may eafily be imagined, that these brilliant fucceffes animated the zeal of all the curious in the metropolis; and that many effays were made to repeat the fame experiments upon a fmaller fcale. Our Author, accordingly, in a third chapter, mentions a number of these fecondary attempts; upon which we fhall dwell no longer than only to obferve, that they fucceeded with globes made of gold-beaters fkin, and only 12 inches in diameter, which being thought the leaft that could be made to ascend, confidering that the proportionate weight of the materials increase as the bulk is diminished, were called minimums.

IV. M. Montgolfier junior, having arrived at Paris a few days before the experiment at the Champ de Mars, was defired

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by the Royal Academy of Sciences to repeat the experiment of Annonay. He accordingly conftructed, in a garden, in the Fauxbourg St. Germain, a balloon of an elliptical form, 70 feet high, and 40 feet in diameter. It was lined, both infide and qutfide, with paper. Its power of afcenfion was found, upon calculation, to be about 1250 lb. It was filled in ten minutes by the burning of 50 lb. of straw and 10 lb. of chopped wool. It was loaded with a weight of 500 lb. and afcended, faftened. to ropes, on the 12th of September, in the prefence of the deputies, of the Royal Academy. But it proving a very rainy day, the whole apparatus was fo effentially damaged, that it was not thought, proper to fet it loose.

V. We come now to the experiment made on the 19th of September, in the presence of the King and Queen, the Court, and all the Parifians who could procure a conveyance to Verfailles. This balloon was 57 feet high and 41 in diameter, Its power of afcenfion, allowing for a wicker cage, containing a heep, a cock, and a duck, which was fufpended to it, was equal to 696 lb. As only four days had been allowed for the making this machine, it could not, therefore, be lined with paper. M. M. had predicted, that it would remain in the air about 20 minutes; and, with a moderate wind, might float to a diftance of about 2000 toifes. But, befide fome imperfection in the conftruction, owing to the great hurry in which it had been made, a fudden guft of wind, while it was inflating, made two rents leven feet long near the top, which could not but in fome measure prevent the promised effect. It fwelled however in 11 minutes fufficiently to raise it about 240 toifes; it floated to the distance of nearly 1700 toifes, and, after having been in the air about eight minutes, it fubfided gradually in the wood of Vaucreffon.The animals in the cage were fafely landed. The sheep was found feeding; the cock had received fome hurt on one of his wings, probably from a kick of the fheep: the duck was perfectly well.

VI. M. Montgolfier determined now to repeat the experiment under more favourable circumftances, and more at his leifure. He therefore made a new balloon, in a garden, in the Fauxbourg St. Antoine, which measured 70 feet in heighth, and 45 feet in diameter. A gallery of wicker was contrived round the apperture at the bottom; under which an iron grate or brazier was fufpended, and port-holes opened on the infide of the gallery, towards the aperture, through which any perfon cui robur et as triplex circa pectus fuerit, who might venture to afcend, might feed the fire on the grate, and thus keep up the vapour, smoke, or as we rather apprehend, the dilatation of the air, in this vaft cavity.