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low. From some experiments they concluded, that they were able by the use of two oars to deviate from the direction of the wind about 22°. But this experiment requires repetition, in order to ascertain with accuracy the effect here ascribed to oars. The second aerial voyage in England was performed by Mr. Blanchard and Mr. Sheldon, professor of anatomy to the Royal Academy, the first Englishman who ascended with an aerostatic machine. This experiment was performed at Chelsea on the 16th of October. The wings used on this occasion seemed to have produced no deviation in the machine's track from the direction of the wind. Mr. Blanchard, having landed his friend about the distance of 14 miles from Chelsea, proceeded alone with different currents, and ascended so high as to experience great difficulty of breathing: a pigeon also, which flew away from the boat, laboured for some time with its wings, in order to sustain itself in the rarefied air, and after wandering for a good while, returned and rested on one side of the boat. Mr. Blanchard perceiving the sea before him, descended near Rumsey, about 75 miles from London, having travelled at the rate of nearly 20 miles an hour. On the 12th of October, Mr. Sadler, of Oxford, made a voyage of 14 miles from that place in 17 minutes, with an inflammable air balloon of his own contrivance and construction. The fate of M. P. de Rozier, the first aerial navigator, and of his companion M. Romain, has been much lamented. They ascended at Boulogne on the 15th of June, with an intention of crossing the channel to England. Their machine consisted of a spherical balloon, 37 feet in diameter, filled with inflammable air, and under this balloon was suspended a small Montgolfier, or fire balloon, ten feet in diameter. This Montgolfier was designed for rarefying the atmospheric air, and thus diminishing the specific gravity of the whole apparatus. For the first twenty minutes they seemed to pursue the proper course; but the balloon seemed to be much inflated, and the aeronauts appeared anxious to descend. Soon, however, when they were at the height of about three quarters of a mile, the whole apparatus was in flames, and the unfortunate adventurers fell to the ground, and were killed, on the spot. On the 19th of July Mr. Crosbie ascended at Dublin, with a view of crossing the channel to England. To a wicker basket of a circular form, which he had substituted for
the boat, he had affixed a number of blad. ders, for the purpose of rendering his gallery buoyant, in case of a disaster at sea. The height to which he ascended at one time was such, that by the intense cold his ink was frozen, and the mercury sunk into the ball of the thermometer. He himself was sick, and he felt a strong impression on the tympanum of his ears. At his utmost elevation he thought himself stationary; but on discharging some gas he descended to a very rough current of air blowing to the north. He then entered a dense cloud, and experienced strong blasts of winds, with thunder and lightning, which brought him with rapidity towards the surface of the water. The water soon entered his car; the force of the wind plunged him into the ocean, and it was with difficulty that he put on his cork jacket. The bladders which he had prepared were now found of great use. The water, added to his own weight, served as ballast; and the balloon maintaining its poise, answered the purpose of a sail, by means of which, and a snatch-block to his car, he moved before the wind as regularly as a sailing-boat. He was at length overtaken by some vessels that were crowding sail after him, and conveyed to Dunleary with the balloon. On the 22d of July, Major Money, who ascended at Norwich, was driven out to sea, and after having been blown about for about two hours, he dropped into the water. After much exertion for preserving his life, and when he was almost despairing of relief, he was taken up by a revenue cutter in a state of extreme weakness: having been struggling to keep himself above water for about seven hours. The longest voyage that had been hitherto made was performed by Mr. Blanchard, towards the end of August. He ascended at Lisle, accompanied by the Chevalier de L'Epinard, and traversed a distance of 300 miles before they descended. On this, as well as on other occasions, Mr. Blanchard made trial of a parachute, in the form of a large umbrella,which he contrived for breakin his fall in case of any accident. With this machine he let down a dog, which came to the ground gently, and unhurt. On the 8th of September Mr. Baldwin ascended from the city of Chester, and performed an aerial voyage of 25 miles in two hours and a quarter. His greatest elevation was about a mile and a half, and he supposes that the velocity of his motion was sometimes at the rate of 20 miles an hour. He has published a circumstantial account of his voyage, deID 2 o
scribed the appearances of the clouds as he passed through them, and annexed a variety of observations relating to aerostation. It would be tedious to recount the aerial expeditions that were performed in various parts of our own country, as well as on the continent, in the whole course of the year 1785: more especially as they have afforded us no experiment or discovery of any peculiar importance. The most persevering aerial navigator has been Mr. Blanchard. In August, 1788, he ascended at Brunswick for the thirty-second time. Within two years from the first discovery of this art of navigating the atmosphere, more than forty different persons performed the experiment without any material injury; and it may be justly questioned, says Mr. Cavallo, whether the first forty persons who trusted themselves to the sea in boats escaped so safely. The catastrophe that befel Rozier, and the unpleasant circumstances that have happened to some of the aeronauts in our own country, have been owing not so much to the principle of the art, as to want of judgment, or imprudent management in the conduct of it. Omitting the various uninteresting, though not very numerous aerial voyages undertaken in various parts of the world, during the 17 years subsequent to the above-mentioned dreadful accident of Pilatre de Rozier and Mr. Romain, we shall only add the account of two aerostatic experiments lately performed in England by Mr. Garnerin, a French aeronaut. The first of these is remarkable for the very great velocity of its motion; the second for the exhibition of a mode of leaving the balloon, and of descending with safety to the ground. On the 30th of June,1802, the wind being strong, though
not impetuous, Mr. Garnerin and another gentleman ascended with an inflammable
air, or hydrogen gas balloon, from Ranelagh gardens, on the south-west of London, between four and five o'clock in the afternoon; and in exactly three quarters of an hour they descended near the sea, at the distance of four miles from Colchester. The distance of that place from Ranelagh is 60 miles; therefore they travelled at the astomishing rate of 80 miles per hour. It seems that the balloon had power enough to keep them up four or five hours longer, in which time they might have gone safely to the contiment; but prudence induced them to descend when they discovered the sea not far off. The singular experiment of ascending into the atmosphere with a balloon, and of
descending with a machine called a parachute, was performed by Mr. Garnerin on the 21st of September, 1802. He ascended from St. George's parade, North Audley Street, and descended safe into a field near the small-pox hospital, at Pancras. The balloon was of the usual sort, viz. of oiled silk, with a net, from which ropes proceeded, which terminated in, or were joined to a single rope at a few feet below the balloon. To this rope the parachute was fastened in the following manner. The reader may easily form to himself an idea of this parachute, by imagining a large umbrella of canvas, of about 30 feet in diameter, but destitute of the ribs and handle. Several ropes, of about 30 feet in length, which proceeded from the edge of the parachute, terminated in a common joining, from which shorter ropes proceeded, to the extremities of which a circular basket was fastened, and in this basket Mr. Garnerin placed himself. The single rope passed through a hole in the centre of the parachute, also through certain tin tubes, which were placed one after the other in the place of the handle or stick of an umbrella, and was lastly fastened to the basket; so that when the balloon was in the air, by cutting the end of the rope next to the basket, the parachute, with the basket, would be separated from the balloon, and, in falling downwards, would be naturally opened by the resistance of the air. The use of the tin tubles was to let the rope slip off with greater certainty, and to prevent its being entangled with any of the other ropes, as also to keep the parachute at a distance from the basket. The balloon began to be filled about two o'clock. There were 36 casks, filled with irou filings, and diluted sulphuric acid, for the production of the hydrogen gas. These communicated with three other casks, or general receivers, to each of which was fixed a tube that emptied itself into the main tube attached to the balloon. At six, the balloon being quite full of gas, and the parachute, &c. being attached to it, Mr. Garnerin placed himself in the basket, and ascended majestically amidst the acclamations of innumerable spectators. The weather was the clearest and pleasantest imaginable; the wind was gentle, and about west by south; in consequence of which Mr. Garnerin went in the direction of nearly east by north. In about eight minutes the balloon and parachute had ascended to an immense height, and Mr. Garnerin, in the basket, could scarcely be perceived. While every spectator was contemplating the
grand sight before them, Mr. Garnerin cut the rope, and in an instant he was separated from the balloon, trusting his safety to the parachute. At first, viz. before the parachute opened, he fell with great velocity; but as soon as the parachute was expanded, which took place a few moments after, the descent became very gentle and gradual. A remarkable circumstance was observed; namely, that the parachute, with the appendage of cords and basket, soon began to vibrate like the pendulum of a clock, and the vibrations were so great, that more than once the parachute, and the basket with Mr. Garnerin, seemed to be on the same level, or quite horizontal: however, the extent of the vibrations diminished as he descended. On coming to the earth, Mr. Garnerin experienced some pretty strong shocks; but he soon recovered his spirits, and remained without any material hurt. As soon as the parachute was separated from the balloon, the latter ascended with great rapidity, and, being of an oval form, turned itself with its longer axis into an horizontal position. We now come to the practice of the art. The shape of the balloon is one of the first objects of consideration. As a sphere admits the greatest capacity under the least surface, the spherical figure, or that which approaches nearest to it, has been generally preferred. However, since bodies of this form oppose a greater surface to the air, and consequently a greater obstruction to the action of the oar or wings than those of some other form, and therefore cannot be so well guided in a calm, or in a course different from the direction of the wind, it has been proposed to construct balloons of a conical or oblong figure, and to make them proceed with their narrow end forward. Next to the shape, it is necessary to consider the stuff that is most proper for forming the envelope of the inflammable or rarefied air. Silk stuff, especially that which is called lutestring, properly varnished, has been most commonly used for hydrogen gas balloons: and common linen, lined within and without with paper, warnished, for those of rarefied air. Varnished paper, or gold beater's skin, will answer the purpose for making small hydrogen gas balloons; and the small rarefied air balloons may be made of paper, without any varnish or other preparation. The stuff for large balloons of both kinds requires some previous preparation. The best mode of preparing the cloth for a machine upon Montgolfier's principle, is first to soak it in a solution of sal-ammoniac and size,
using one pound of each to every gallon of water; and when the cloth is quite dry, to paint it over with some earthy colour, and strong size or glue. It may be also varnished over when perfectly dry, with some stiff, oily varnish, or simple drying linseed oil, which would dry before it penetrates quite through the cloth. The pieces of which an hydrogen gas balloon is to be formed must be cut of a proper size, according to the proposed dimensions of it, when the varnish is sufficiently dry. The pieces that compose the surface of the balloon are like those gores that form the superficies of a globe: and the best method of cutting them is to describe a pattern of wood or stiff card-paper, and to cut the silk or stuff upon it. To the upper part of the balloon there must be adapted a valve, opening inward, to which is annexed a string passing through a hole made in a small round piece of wood, which is fastened to the lowest part of the balloon, opposite to the valve, to the boat below it; so that the aeronaut may open it as occasion requires, and let the hydrogen gas out of the balloon. To the lower part of the balloon are fixed two pipes of the same stuff with the covering, six inches in diameter for a balloon of 30 feet, and much larger for balloons of greater size, and long enough to reach the boat. These pipes are the apertures through which the hydrogen gas is introduced into the balloon. The boat may be made of wicker work, and covered with leather, well painted or varnished over. The best method of suspending it is by means of ropes, proceeding from the net which goes over the balloon. This net should be formed to the shape of the balloon, and fall down to the middle of it, and have various cords proceeding from it to the circumference of a circle, about two feet below the balloon; and from that circle other ropes should go to the edge of the boat. This circle may be made of wood, or of several pieces of slender cane bound together. The meshes of the net may be small at top, against which part of the balloon the hydrogen gas exerts the greatest force, and in
crease in size as they recede from the top.
A hoop has been sometimes put round the middle of the balloon for fastening the met. This is not absolutely necessary; but when used, it is best made of pieces of cane bound together, and covered with leather. When the balloon and its appendages are constructed, the next object of importance is to procure proper materials for filling it. Hydrogen gas for balloons may be obtained
in several ways: but the best methods are by applying acids to certain metals; by exposing animal, vegetable, and some mineral substances, in a close vessel, to a strong fire; or by transmitting the vapour of certain fluids through red-hot tubes. In the first of these methods, iron, zinc, and sulphuric acid are the materials most commonly used. The acid must be diluted with five or six parts of water. Iron may be expected to yield in the common way about 1700 times its own bulk of gas; or 4 ounces of iron, the like weight of sulphuric acid, and 224 ounces of water, will produce one cubic foot of hydrogen gas; 6 ounces of zinc, an equal weight of acid, and 30 ounces of water, are necessary for producing the same quantity. It is more proper to use the turnings or chippings of great pieces of iron, as of cannon, &c. than the filings of that metal, because the heat attending the effervescence will be diminished, and the diluted acid will pass more readily through the interstices of the turnings, when they are heaped together, than through the filings, which stick closer to one another. The weight of the hydrogen gas thus obtained by means of sulphuric acid, is, in the common way of procuring it, generally one-seventh part of the weight of common air; and with the necessary precautions for philosophical experiments, less than one-tenth of the weight of common air. We shall conclude this article with a description of some figures explanatory of the subject. Figure 1 (plate Aerostation) represents a balloon, DF, suspended by means of the poles G and H, and the cord, for the purpose of being filled with gas. It is kept steady and held down whilst filling by ropes, which are readily disengaged. A, A, are two tubs, about three feet in diameter, and two feet deep, inverted in larger tubs, B, B, full of water. At the bottom of each of the inverted tubs there is a hole, to which is inserted a tin tube; to these the silken tubes of the balloon are tied. Each of the tubs, B, is surrounded by several strong casks, so regulated in number and capacity, as to be less than half full when the materials are equally distributed. In the top of these casks are two holes; to one of which is adapted a tin tube, formed so as to pass over the edge of the tub B, and through the water, and to terminate with its aperture under the inverted tub A. The other hole, which serves for supplying the cask with materials, is stopped with a wooden plug. When the balloon is to be filled, the common air is first to be expelled, then the
silken tubes are fastened round the tin ones; the iron filings are to be put into the casks, then the water, and lastly the sulphuric acid. The balloon will speedily be inflated by the gas, and support itself without the aid of the rope GH. As the filling advances, a met is adjusted about it, the cords proceeding from the net are fastened to the hoop MN; the boat IK is suspended from the hoop, and whatever is wanted for the voyage is deposited in the boat. When the balloon is sufficiently full, the silken tubes are separated from the tin tubes, their extremities are tied, and they are placed in the boat. When the aeronauts are seated in the boat, the ropes that held the balloon down are slipped off, and the machine ascends in the air as in figure 2. In figure 3, is a representation of apart of Mr. Garnerin's balloon in its ascent, to which is attached the parachute in its contracted state, and below is the car. Figure 4 shews the manner in which Mr. Garnerin descended in the car by means of the expanded parachute, after he had detached it from the balloon. In figure 5 is represented an apparatus, as described by Mr. Cavallo, for filling balloons of the size of two or three feet in diameter with hydrogen gas, after passing it through water. A is a bottle with the ingredients; BCD a tube fastened in the neck at B, and passing through C, the cork of the other bottle, in which there is a hole made to receive the tube, and to this the balloon is tied. Thus the hydrogen gas, coming out of the tube D, will pass first through the water of the bottle E, and then into the balloon. Two small casks may be used instead of the bottles A and E. HERVA, in botany, a genus of the Monadelphia Decandria class and order. The flowers are polygamous; the calyx five-leaved and patent: the stamina are five; the pistillum is a globulous ovary, having a filiform style, terminated by a bifid stigma: the fruit is an oblong, single-seeded capsule, encompassed by a calyx; there is but one species, viz. the AE. aegyptiaca, or tomentosa, which grows on the sandy calcareous soil of Arabia. AESCHYNOMENE, a word from the Greek, signifying to be ashamed, because it retreats from the touch: bastard sensitive plant, in botany, a genus of the Diadelphia Decandria class and order, and of the natural order of Papilio Naceae, of which there are 12 species found native in the East Indies, and cultivated in other hot countries. One of the species may be treated as hemp, and is used for the same purposes.
AESCULUS, in botany, a genus of the Heptandria Monogynia class and order, of the natural order of Trihilatae. There are three species: the first, or common horsechestnut, was brought from the northern parts of Asia into Europe about the year 1550, and sent to Vienna about the year 1558. From Vienna it was conveyed to France and Italy; but it came to us from the Levant. It is distinguished by the beautiful parabolic form of its branches, the disposition and structure of its digitate leaves, and by the pyramidal bunches of its white flowers, variegated near the centre with yellow or red. Although this tree is now less in esteem for avenues and walks than it formerly was, on account of the early decay of its leaves, it affords an excellent shade; and the spikes of flowers which appear in May, with the intermixture of large leaves, exhibit a noble appearance. The most eligible situation for these trees is in lawns and parks, where they may be planted singly, and where their fruit will be serviceable to the deer, who are fond of it. This tree is of quick growth; and in a few years it will afford a good shade in summer, and yield plenty of flowers. Trees, raised from nuts, have in 12 or 14 years become large enough to shade two or three chairs with their branches, which in the season are covered with flowers. But the trees are of short duration, and the wood is of little value. It serves, however, for water-pipes, turner's ware, and fuel: and for these uses it is worth the charge of planting, and should be felled in November or December. The horse-chesnut has been employed in France and Switzerland for the purpose of bleaching yarn; and it is recom. mended in the Memoirs of the Society of Berne, Vol. II. part 2, as capable of extensive use in whitening not only flax and hemp, but silk and wool. It contains an astringent saponaceous juice, which is obtained by peeling the nuts, and grinding or rasping them. 'l'hey are then mixed with hot rain or running water, in the proportion of 20 nuts to 10 or 12 quarts of water. Wove caps and stockings were milled in this water, and took the dye extremely well; and successful trials were made of it in fulling stuffs and cloths. Linen washed in this water takes a pleasing light sky-blue colour; and the filaments of hemp, steeped in it some days, were easily separated. The author of the memoir, above referred to, imagines, that if the meal of the chestnuts could be made into cakes or balls, it would answer the purposes of soap, in washing and full
ing. The sediment, after infusion, loses its bitter taste, and becomes good food for fowls when mixed with bran. The Edinburgh College have admitted the horsechestnut into their Pharmacopoeia of 1783, on the recommendation of Dr. Gardiner, who says, that three or four grains of the powder snuffed up the mostrils in the evening, operate next morning as an excellent sternutatory, and thereby proves very beneficial in obstinate inflammations of the eyes. A patent was granted, in 1796, to Lord W. Murray, for his discovery of a method of extracting starch from horsechestnuts. w The second species, or yellow-flowered horse-chestnut, is a native of North Carolina, was cultivated with us in 1764, and flowers in May and June. The third species, or scarlet horse-chestnut, rises to the height of twenty feet, without much extending its branches; its bark is smooth, and the leaves, which are opposite, on long, red petioles, are of a light green. The common horse-chestnut is propagated by sowing the nuts, after preserving them in sand during the winter: but the scarlet is propagated by grafting it upon stocks of the common horse-chestnut. AETHUSA, in botany, a genus of the Pentandria Digynia class and order, and belonging to the natural order of Umbellatae or Umbelliferae: the calyx is an universal spreading umbel, and the partial is also spreading, but small; having no universal involucre, and the partial one placed on the outside, and consisting only of three very long, linear, pendulous leaflets, and the proper perianthium scarcely observable: the universal corolla is nearly uniform, with all the floscules fertile, and the partial has the petals bent in, heart-shaped, and unequal: the stamina are simple filaments, with roundish anthers; the pistillum is an inferior germ, and the styles are reflex, with obtuse stigmas: it has no pericarpium, and the fruit is roundish, streaked and bipartile: the seeds are two, roundish, streaked, except on a third