IN every stage of society men have eagerly sought, by the combination of superior skill and ingenuity, to attain those distinct advantages which nature has conferred on the different tribes of animals, by endowing them with a peculiar structure and a peculiar force of organs. The rudest savage learns from his very infancy to imitate the swimming of a fish, and plays on the surface of the water with an agility and a perseverance which seem to decline with the advancement of civilisation. But an art so confined in its exercise, and requiring such a degree of bodily exertion, could not be considered of much avail. It was soon perceived, that the fatigue of impulsion through the water could be greatly diminished, by the support and floating of some light substance. The trunk of a tree would bear its rude proprietor along the stream; or, hollowed out into a canoe, and furnished with paddles, it might enable him even to traverse a river. From this simple fabric, the step was not great to the construction of a boat or barge, impelled by the force of oars. But it was a mighty stride to fix masts and apply sails to the vessel, and thus substitute the power of wind for that of human labour. The adventurous sailor, instead of plying on the narrow seas, or creeping timidly along the shore, could now launch with confidence into the wide ocean. Navigation, in its most cultivated form, may be fairly regarded as the consummation of art, and the sublimest triumph of human genius, industry, courage, and perseverance.
Having by his skill achieved the conquest of the waters that encompass the habitable globe, it was natural for man to desire likewise the mastery of the air in which we breathe. In all ages, accordingly, has ingenuity been tortured in vain efforts at flying. The story of Icarus testifies how fatal such daring attempts had generally proved to their projectors. Trials made with automata, though less liable to risk and danger, were yet equally fallacious. Archytas, a most eminent Greek geometer and astronomer, who perished by shipwreck on the coast of Calabria, was believed by his admiring contemporaries to have constructed an artificial dove, which, by the action of a system of internal springs, wafted itself through the air. If such a piece of mechanism was ever made, we may be sure that its flight was really produced, as in the scenes of the opera, by means of invisible strings or wires.
So thoroughly were the ancients convinced of the impossibility of men being able to fly, that they ascribed the absolute rule of the sky to divinities of the first order. The supreme Jupiter alone reposed on his empyreal throne, far above the heights of Olympus; and to him was it given, from the region of the clouds, to point the winged lightning, and to hurl the flaming thunderbolt. On special missions he dispatched Mercury, as his messenger, through the wide range of atmosphere. The oriental nations, from whom we have borrowed the greater part of our vulgar mythology, likewise committed such journeys to certain genii or ministering spirits. But the glowing visions of the East received a darker tinge from the character and climate of our Gothic ancestors. The archfiend himself was, at no very distant period, firmly believed to have the especial control of the air, and to career in the whirlwind and impel the howling tempest. Those wretched creatures whom the unfeeling credulity of our ancestors, particularly during the prevalence of religious fanaticism, stigmatized and murdered under the denomi-
nation of witches, were supposed to work all their enchantments, to change their shapes at will, and to transport themselves through the air with the swiftness of thought, by a power immediately derived from their infernal master. At a period somewhat earlier, every person in possession of superior talents and acquirements was believed to deal in magic, and to perform his feats of skill chiefly through the secret aid granted him by the prince of darkness. In spite of the incurable perverseness of his conduct, it must be confessed that the devil has always had the credit of retaining some little inclination to assist the efforts of genius.
During the darkness of the middle ages, every one at and to man-
all distinguished by his knowledge in physics was gene-
rally reputed to have attained the power of flying in the
air. Our famous countryman Friar Bacon, among other
dreams engendered in his fervid brain, has not scrupled to
claim the invention of that envied and transcendent
art. To these pretensions the credulity and indulgent
admiration of some authors have lent more credit than
they really deserved. Any person who will take the
trouble to examine the passages of Bacon's obscure though
ponderous works, must soon be convinced, that the pro-
positions advanced by him are very seldom founded on
reality, but ought rather to be considered as the sportive
illusions of a lively and teeming fancy. Albertus Magnus,
who lived about the same period, and was esteemed in
Germany as a perfect prodigy, pretended also to the art of
flying. More than a century afterwards, John Müller of
Königsberg, and thence styled Regiomontanus, one of the
chief restorers of genuine mathematical learning in Europe,
was reported by some writers of note to have, like Archy-
tas, fashioned an artificial dove, which displayed its wings,
and flew before the emperor Charles V. at his public
entrance into Nuremberg. But, unfortunately for the
veracity of the story, Regiomontanus died in early life,
full sixty years before that visit took place.
While the belief in necromancy prevailed, such tales
assumed colours of the most lurid hue. Fiery dragons, tures of
created by infernal machination, were imagined to rush that art.
impetuous through the sky, vomiting flames, and widely
scattering the seeds of pestilence. Grave writers, in
those benighted ages, even ventured to describe the meth-
od of imitating the composition of such terrific monsters.
A mass of large hollow reeds were to be disposed and
bound together, then sheathed completely in skin, and
smeared over with pitch and other inflammable matters:
this light and bulky engine, partially set on fire, and
launched in the thickest darkness into the air, might be
sufficient, when borne along by the force of the wind, to
strike the ignorant populace with affright and horror.
But such spectacles would come to lose their terrors by
repeated failure and the insensible progress of knowledge.
So late as the year 1750, a small Catholic town in Swabia
was almost entirely burnt to ashes by an unsuccessful exper-
iment of that sort, instigated, and probably directed, no
doubt for the edification of their flock, by the lowest or-
der of priests. It was attempted to represent the effigy
of Martin Luther, whom the monks firmly believe to be
the very imp of Satan, under the form of a winged serpent,
furnished with all the requisite appendages of a forked tail
and hideous claws. Unluckily for the skill of the machinist,
this phantom directly fell against the chimney of a house,
to which it set fire; and the flames spreading furiously in
Aeronau- every direction, the people had soon cause to lament hit-
tics. terly their intemperate zeal.
Later at- The scheme of flying in the air, which men of the first
tempts at flying. genius had once entertained, appears to have gradually
descended to a lower class of projectors. Those who
afterwards occupied themselves with such hopeless at-
tempts, had commonly a smattering of mechanics, with
some little share of ingenuity, but wrought up by exces-
sive conceit.
In the beginning of the sixteenth century, an Italian
adventurer visited Scotland, during the reign of James
IV.; and being a man of some address, and at the same
time a pretender to alchemy, he contrived to insinuate
himself into the favour of that gay and needy prince, by
holding out hopes of augmenting his scanty treasury by
the acquisition of the philosopher's stone. He was collat-
ed by royal favour to the abbacy of Tungland in Galloway;
but not having succeeded in creating artificial riches, he
resolved, in the height of his enthusiasm, at once to grat-
ify and astonish the courtiers, by the display of a feat
still more extraordinary. Having constructed a set of
ample wings, composed of various plumage, he undertook,
from the walls of Stirling Castle, to fly through the air to
France. This experiment he had actually the folly or
hardihood to try; but he soon came to the ground, and
broke his thigh-bone by the violence of the fall. For his
unlucky failure, however, the abbot had the dexterity to
draw a very plausible excuse from the wretched sophistry,
termed science in that age. "My wings," said the artful
Italian, "were composed of various feathers; among them
were the feathers of dunghill fowls, and they, by a certain
sympathy, were attracted to the dunghill; whereas, had
my wings been composed of the feathers of eagles alone,
the same sympathy would have attracted them to the re-
gion of the air." This anecdote has furnished to Dunbar,
the Scottish poet, the subject of one of his rude Satires.
A century afterwards, Fleyder, rector of the grammar-
school at Tübingen, entertained, in 1617, the worshipful
magistrates of that city with a lecture on the art of flying,
which he published at the lapse of eleven years, yet pru-
dently contented himself with barely explaining his theory.
A poor monk, however, ambitious to reduce this theory
into practice, having provided himself with spacious wings,
took his flight from the top of a high tower; but encoun-
tering a cross wind, his machinery misgave, and falling
precipitously to the ground, he broke both his legs, and
perished miserably. An accident of a similar kind is re-
lated to have happened not long since near Vienna.
Impossib- The impossibility of rising, or even remaining suspen-
lity of fly- ded in the air, by the action of any machinery impelled by
ing first human force, was first demonstrated by Borelli, a most
demon- eminent Italian mathematician and philosopher, who lived
strated by in the fertile age of discovery, and was thoroughly ac-
Borelli. quainted with the true principles of mechanics and pneu-
matics. In his celebrated and excellent work De Motu
Animalium, published in 1670, he showed, by accurate
calculation, the prodigious force which the pectoral mus-
cles of birds must exert and maintain. The same principles,
applied to the structure of the human frame, proved
how very disproportionate was the strength of the cor-
responding muscles in man. It is not, therefore, the mere
difficulty of contriving and combining machinery which
should perform the peculiar motions of wings, that has
rendered all attempts of the kind futile, but the utter
want of adequate force in the human body to give such
impulsion to those extended vanes as would be necessary
for supporting so great a weight in the thin medium of
the atmosphere.
Having found by experience the impossibility, from
any application of inherent strength, of ascending into Aeronau-
the atmosphere, it was natural for men of ardent minds, tics.
who still pursued that dazzling project, to look for some
extraneous aid among the varied powers of the elements.
The notions entertained by the ancients respecting the Cosmol-
composition of the world might have suggested important o-
hints for realizing the scheme of aerial navigation. The tics of the
four elements—earth, water, air, and fire or ether, ar- ancients.
ranged according to their several qualities and tendencies,
were supposed to constitute this universal frame. Earth,
being heavy and inert, occupies the centre of the system,
and above it flowed the waters; air, from its lightness,
rose upwards, and invested the globe with an atmosphere;
while the diffuse ethereal substance soared, by its extreme
buoyancy, to the celestial regions, and filled with splen-
dour their pure expanse. Every portion of these distinct
elements, if transported from its place, was conceived as
having a natural and constant appendency to return to its
original situation. Earth and water sink downwards by
their gravity, while air and fire, endowed with an opposite
principle, as invariably rise to the higher spaces. A por-
tion of fire, joined to water or to air, communicates, in a
corresponding degree, its levity, or disposition to ascend.
Thus, warm air always rises; water, subdued by excessive
heat, flies upwards in the form of vapour; and the volatile
parts of inflamed bodies are borne to the sky in smoke.
The first person that seems to have formed a just idea of
the principle on which a balloon could be constructed sailing
was Albert of Saxony, a monk of the respectable order of
St Augustin, who lived in the fourteenth century, and
wrote a learned commentary on the physical works of
Aristotle. Since fire is more attenuated than air, and
floats above the region of our atmosphere, this ingenious
person conceived that a portion of such ethereal substance,
inclosed in a light hollow globe, would raise it to a cer-
tain height, and keep it suspended in the sky. But the
same philosopher rightly subjoined, that a greater mixture
of air introduced into the balloon, by rendering this heavier
than before, would cause it to descend proportionally, in
the same way precisely as water admitted through the
seams of a ship makes the vessel to sink in the ocean.
It is evident that nothing was wanted for completing
Montgolfier's discovery, but to carry those fine views into
execution.
The ideas of Albert of Saxony were long afterwards and
zealously embraced by Francis Mendoza, a Portuguese by Meu-
Jesuit, who died at Lyons in the course of a tour through
France in 1626, at the age of 46. He maintained that
the combustible nature of fire was no real obstacle to its
application in balloons, since its extreme levity, and the
exclusion of the air, would hinder it from supporting in-
flammation. Casper Schott, a Jesuit likewise, pursued and Casper
more soberly the same speculation in Germany. He Schott.
stated that no air of these lower regions is ever light
enough to produce an ascent, and that the lucid ethereal
matter which swims above our atmosphere is alone fit-
ted for aerial navigation. Were any superhuman power,
therefore, to bring down a store of that buoyant substance,
to be inclosed in a hollow ball of wood or thin lead, the
vessel, being furnished with a rudder and sails, might
then, he conceived, boldly navigate the sky.
Similar notions have been renewed at different times. Blended
They were likewise often blended with the alchemical with alche-
tenets so generally received in the course of the fifteenth, mical no-
sixteenth, and part of the seventeenth centuries. Con- tions.
ceiving with the ancients that the dew which falls during
the night is of celestial origin, and shed by the stars,
speculative men still imagined this pure humidity to be
drawn up again to the heavens by the sun's rays in the
Aéronautics. heat of the day. Many persons, imbued with the wretched learning of that age, had the simplicity to believe that an egg-shell filled with the morning dew, and placed at the foot of a ladder leaning against the roof of a house, would, as the day advanced, spontaneously rise along the whimsical bars, and mount to the chimney-tops. This whimsical projects of fancy is confidently related as an observed fact by Father Lauretus Laurus. "Take," says he, very gravely, "a goose egg, and, having filled it with dew gathered fresh in the morning, expose it to the sun during the hottest part of the day, and it will ascend, and rest suspended for a few moments." To perform the experiment on a greater scale, however, he proposed to employ the largest swan's egg, or a bag artificially prepared from the thinnest and lightest skin, into which, instead of dew, he would introduce the three alchemical elements, nitre, sulphur, and mercury; and he imagined that these active bodies, expanded and sublimed by the mere heat of the sun, must spring powerfully upwards. In this way he thought the dove of Archytas might be constructed. But the visionary priest had yet another scheme to advance for effecting the ascent of the automaton: he proposed to cram the cavity of the dove with highly condensed air; and was so grossly ignorant of the principles of motion as to suppose that this imprisoned fluid would impel the machine in the same manner as wind does a sail. Should such a force be found not sufficiently efficacious, he finally recommended the application of fire: not, however, on account of its buoyant property, but because of the propulsive power which it exerts. To prevent the fire from consuming the wooden machine, he recommends lining the inside with cloth of asbestos or other incombustible materials; and to feed and support steadily this fire, he suggested a compound of butter, salts, and orpiment, lodged in metallic tubes, which he imagined would at the same time heighten the whole effect, by emitting a variety of musical tones like an organ.
Proposals of Cardan and Fabry. Influenced by the same views, other authors, and particularly the famous Cardan, have proposed, for aerial ascents, to apply fire acting as in a rocket. Still later, but in the same country, Honoratus Fabry, penitentiary of the pope, and teacher in the gymnasium at Rome, who died about the end of the seventeenth century, described a huge apparatus, consisting of very long tin pipes, in which air was compressed by the vehement action of fire below. In a boat suspended from the machine, a man was to sit and direct the whole, by the opening or shutting of valves.
Philosophical romance of Cyrano de Bergerac. The projects and vagaries of learned men about the misty period of the restoration of science were finely ridiculed by Cyrano de Bergerac, a very witty and eloquent French writer, in a philosophical romance, entitled The Comical History of the States and Kingdoms in the Sun and Moon. This eccentric genius, born at Périgord in 1620, was noted for his impetuous temper and boiling courage. He spent his youth in dissipation and feats of arms; but afterwards, in riper life, he quitted the military profession, and betook himself to the study of poetry and philosophy, which he prosecuted with great ardour and success till he died, at the early age of 35. In his romance, from which perhaps Swift borrowed the idea of Gulliver's voyage to Laputa, Bergerac introduced a good deal of the Cartesian philosophy, then just coming into vogue; but lashed severely the pedantry and ignorance of various pretenders to science. To equip himself for performing the journey to the moon, the French traveller fastens round his body a multitude of very thin flasks filled with the morning's dew. The heat of the sun, by its attractive power exerted on the dew, raised him up to
the middle region of the atmosphere; where some of his Aéronautics flasks happening unluckily to break, the adventurer sunk again to the ground, and alighted in Canada. There he constructed a new machine, acting by a train of wheels, with which he mounted to some height; but falling down, he had the misfortune to break his leg. He crept aside, in search of ox-marrow to compose a salve, with which he instantly healed his bruises; and returning again, he found his engine in the possession of some soldiers, who had fixed to it a number of sky-rockets. Replacing himself now in the car, he applied fire to the rockets, and darted upwards with inconceivable swiftness: the earth retired gradually from view, while the orb of the moon appeared proportionally to expand, till, approaching the sphere of her activity, he was borne softly along, and descended on the lunar surface into a most delicious and luxuriant grove. Here, of course, he met with angelic personages, endowed with every perfection of body and mind, and far exalted above the mean vices and the rancorous passions which poison and inflame the inhabitants of this blood-stained globe. In the conversations which Bergerac held with those supernal beings, he was informed that a native of our planet, utterly disgusted at the crimes which pollute its "sin-worn mould," had once on a time provided himself with a pair of very large and thin metallic vessels, which he filled with smoke, and sealed in the light; and having attached himself below them, the buoyant power of the confined smoke carried him to the highest region of our atmosphere, where the attraction of the moon at length prevailing, drew him to her surface, while the great extent of the machinery, by opposing resistance, served to break the force of his fall. The moment, however, those slender capacious vessels were liberated from his weight, they rose again by the action of the smoke, till they reached a medium of the same density, and finally took their station in the bright fields of ether, where they form the constellation now called the Balance.
In further discourse with his sublime instructor, our romantic voyager was shown how to obtain the power of ascension from the loadstone. He was directed to take two magnets, each about a foot square, to roast them in the fire, to separate their impurities by solution, and thus concentrate their attractive virtue in a mere calx, which could be formed into a ball. Aided by such counsels, he now resolved to visit the sun. With much labour and perseverance he constructed a chest of very thin steel, six feet high and three feet wide; an icosahedron of crystal, the highest of all the regular solids, being fitted into the top, and the bottom having a small valve which opened outwards. Into this chest he shut himself, while the sun's rays, concentrated and multiplied by reflection from the numerous facets of the crystal, heated the air intensely, and drove a great part of it out below; and he ascended rapidly towards the glorious luminary, breathing ecstatically in divine light, which gleamed with the richest tints of enamelled gold and purple. But it would be foreign to our purpose to follow the rest of the narrative, which, though disguised and mingled with fantastic visions, evidently contains the true principles of aeronautics.
The most noted and elaborate scheme for navigating Lana's the atmosphere was proposed by the Jesuit Francis Lana, scheme for navigating the air. in a book written in the Italian language, and printed at Brescia in 1670, with the aspiring title of Prodromo dell'Arte Maestra. His project was to procure four copper balls of very large dimensions, yet so extremely thin, that, after the air had been extracted, they should become, in a considerable degree, specifically lighter than the surrounding medium. He entered into some calculations to prove that the buoyant power thus obtained would be
Aéronautics. fully adequate to produce the desired effect. Yet he seems to have had only a slender knowledge of geometry, and but little acquaintance with the progress of physical science. For instance, he found his computations entirely on the pneumatical discoveries of Galileo and Toricelli, without making any reference to those important facts which the invention of the air-pump by Otto Guericke had successfully detected in the course of near 30 years. He assumes that air is 640 times lighter than water; that a cubic foot of water weighs 80 pounds, and consequently that the weight of the same bulk of air is an ounce and a half. If we rectify the estimate of Lana, and reduce it to English measures, each of his copper balls had about 25 feet in diameter, with the thickness of only the 225th part of an inch, the metal weighing 365 pounds avoirdupois, while the weight of the air which it contained must amount to 670 pounds, leaving, after a vacuum had been formed, an excess of 305 pounds, for the power of ascension. Those four balls would therefore rise together into the atmosphere with a combined force of 1220 pounds, which was thought sufficient by the projector to transport a boat completely furnished with masts, sails, oars, and rudders, and carrying several passengers. To extract the air from their cavities, the method proposed was, to procure a Toricellian vacuum, by connecting each globe, fitted with a stop-cock, to a tube of at least thirty-five feet long; the whole being filled with pure water, and raised gently into a vertical position, the mass of liquid, exceeding the pressure of the atmosphere, would flow out, and subside to some point below the cock, which could then be shut.
His attempts to answer objections. Lana enumerates the different objections which might be urged against his scheme, and endeavours to answer them. He thinks that the spherical and perfectly arched form of the shell of copper would, notwithstanding its extreme thinness, enable it, after the exhaustion was effected, to sustain the enormous pressure of the external air, which, acting equally on every point of the surface, would rather tend to consolidate than to crush or tear the metal. As the atmosphere becomes always lighter in the upper regions, the machinery could only rise to a certain limit; and if this were found too high for easy breathing, the ascent could be regulated by opening occasionally the cocks to admit some air into the cavity of the balls, and thus increase their specific gravity. There seemed to him no very great difficulty in directing and impelling the aerial bark, by means of rudders, oars, and sails; but the objection was more serious on account of the hazards of tremendous shipwreck, from the violence of winds and tempests. Yet what most alarmed the insinuating Jesuit, and which he earnestly prays God to avert, was the danger that would result, from the successful practice of the art of aeronautics, to the existence of civil government, and of all human institutions. No walls or fortifications could then protect cities, which might be completely subdued or destroyed, without having the power to make any sort of resistance, by a mere handful of daring assailants, who should rain down fire and conflagration from the region of the clouds.
So sanguine was Lana, as to conceive that the very moderate sum of a hundred ducats would be sufficient to defray the expense of all this huge and delicate apparatus. But his poverty, fortunately, no doubt, for his credit as a man of learning, prevented him from proceeding further than mere speculation; and none of the foreign princes, who about that period often squandered, like gamesters, much of their wealth in the dark and chimerical search after the philosopher's stone, seemed any way disposed to engage in the magnificent scheme of aerial navigation.
Aéronautics. The project of Lana appears to have in some degree excited the attention of the learned, though it was at the same time very generally condemned. Hooke, Borelli, Leibnitz, and Sturmius, examined it, and severely exposed its defects. Indeed, any person at all acquainted with actual experiment must see that it was absolutely impracticable. Passing over other circumstances, the attenuated shell of copper, from its size and excessive thinness, could not have strength enough to support even its own weight, far less the slightest pressure of the atmosphere. The plate, however, that Lana has given of his whole combined apparatus appears very striking; and after Montgolfier's discovery, it could not fail to attract a greater share of notice than it was otherwise entitled to claim.
So late as the year 1755, and not very long before the Project of final invention of balloons, a very fanciful scheme, yet on Galien. the grandest scale, for navigating the atmosphere, was published with most circumstantial detail, in a small pamphlet, by Joseph Galien, a Dominican friar, and professor of philosophy and theology in the papal university of Avignon. This visionary proposed to collect the fine diffuse air of the higher regions, where hail is formed, above the summit of the loftiest mountains, and to inclose it in a bag of a cubical shape, and of the most enormous dimensions, extending more than a mile every way, and composed of the thickest and strongest sail-cloth. With such a vast machine, far outvalling in boldness and magnitude the ark of Noah, it would be possible, he thought, to transport a whole army, and all their armaments of war. But we need not stop one moment to consider a project so perfectly chimerical, which involves, besides, the erroneous supposition that the air of the upper regions is, independently of its diminished compression, essentially thinner and more elastic than the air below.
It cannot fail to strike the reader, that the persons who have occupied themselves the most with attempts at aerial navigation, were all of them Catholic priests;—whether this pursuit is to be explained from their habits of seclusion and their ignorance of the affairs of real life, or from their familiar acquaintance with the relations of miracles and other legendary tales, which might lead them to see nothing very extraordinary in the art of flying through the air. The various schemes of that kind, produced at different times, contain a few just principles, generally mixed up, however, with a large portion of absurdity. But very wide is the distance from such speculations to the real exhibition of the experiment itself.
Some writers have stated that Lord Bacon first published the true principles of aeronautics. This round assertion we cannot help noticing, because it has really no foundation, except in the propensity, fostered by indolence, which would gladly refer all the discoveries ever made to a few great names. They mistake, indeed, the character of Bacon, who seek to represent him as an inventor. His claim to immortality rests chiefly on the profound and comprehensive views which he took of the bearings of the different parts of human knowledge; for it would be difficult to point out a single fact or observation with which he enriched the store of physical science. On the contrary, being very deficient in mathematical learning, he disregarded or rejected some of the noblest discoveries made in his own time.
We can find only two passages in Lord Bacon's works which can be considered as referring to aeronautics, and they both occur in that collection of loose facts and inconclusive reasonings which he has entitled Natural History. The first is styled Experiment Solitary, touching Flying in the Air, and runs thus: "Certainly many birds of good wing (as kites and the like) would bear up a good
Aéronautics. weight as they fly; and spreading feathers thin and close, and in great breadth, will likewise bear up a great weight, being even laid, without tilting up on the sides.
The further extension of this experiment might be thought upon. This hint is not in fairness obnoxious to stricture, since the ingenious Bishop Wilkins, twenty years afterwards, still believed that men could acquire the art of flying. Nor was there any reason to despair, till Borelli at length demonstrated its absolute impossibility. The second passage is more diffuse, but less intelligible: it is styled Experiment Solitary, touching the Flying of unequal Bodies in the Air. "Let there be a body of unequal weight (as of wool and lead, or bone and lead); if you throw it from you with the light end forward, it will turn, and the weightier end will recover to be forwards, unless the body be over long. The cause is, for that the more dense body hath a more violent pressure of the parts from the first impulsion; which is the cause (though heretofore not found out, as hath been often said) of all violent motions: and when the hinder part moveth swifter (for that it less endureth pressure of parts) than the forward part can make way for it, it must needs be that the body turn over; for (turned) it can more easily draw forward the lighter part." The fact here alluded to is the resistance that bodies experience in moving through the air, which depending on the quantity of surface merely, must exert a proportionally greater effect on rare substances. The passage itself, however, after making every allowance for the period in which it was written, must be deemed confused, obscure, and unphilosophical.
True theory of balloons. That a body must remain suspended in a fluid denser than itself, was first established by Archimedes, whose propositions in hydrostatics were further extended in modern times by Stevinus and other early mathematicians. But the principles on which a balloon could be made to rise in the atmosphere were scarcely understood till very long afterwards, when chemistry, near the latter part of the last century, had succeeded in ascertaining the properties of the different kinds of æriform substances. The Greeks of the lower empire knew that air is greatly dilated by warmth; and Sanctorio, the ingenious medical professor at Padua, by applying this expansion, about the year 1590, to the construction of the thermometer, had happily placed it in a strong light. His countryman Borelli remarked, almost a century afterwards, that a heated iron or a burning taper brought near one of the scales of a well-poised balance, by exciting a vertical current, will cause it to mount up with force,—a fact which affords the only true explication of the numerous experiments of Buffon with the weighing of red-hot balls, whose regular and constant results appeared to that eloquent philosopher to exhibit a conclusive demonstration of the actual ponderability of heat. Yet warm air, alone and unassisted, has still no very great power of ascension. The buoyancy communicated to that fluid by the distensible vapour of water and other more volatile liquids is in some cases considerable, especially when combined at the same time with heat. But those æriform substances which are more elastic than common air display the most steady and powerful tendency to rise in the atmosphere. Such, in a remarkable degree, is the hydrogen gas, owing probably to the expansive force communicated by the very large share of heat which is embodied with it. The late most ingenious and accurate Mr. Cavendish, in 1766, found, by a nice observation, this fluid to be at least seven times lighter than atmospheric air. It therefore occurred to Dr. Black of Edinburgh, that a very thin bag filled with hydrogen gas would rise to the ceiling of a room
He provided, accordingly, the allantois of a calf, with the view of showing, at a public lecture, such a curious experiment before his numerous auditors; but, owing to some unforeseen accident or imperfection, it chanced to fail, and that celebrated professor, whose infirm state of health and cold or indolent temper more than once allowed the finest discoveries, when almost within reach, to escape his penetration, did not attempt to repeat the exhibition, or seek to pursue the project any farther. Several years afterwards, a similar idea occurred to Mr. Cavallo, who found, however, that bladders, though carefully scraped, are too heavy, and that China paper is permeable to the gas. It is rather singular that he did not think of gold-beater's skin, which had for like purposes been recommended two centuries before by the grammarian Joseph Scaliger and some other writers. But in 1782 this ingenious person succeeded with the pretty experiment of elevating soap-bubbles, by inflating them with hydrogen gas.
To construct an aeronautic machine, it is only required, therefore, to provide a thin bag, of sufficient capacity, and to fill it with hydrogen gas, or with air which is kept in a rarefied state. The form and strength of the material are not so essential as in Lana's project, since it here suffers an equal pressure on both its outer and its inner side. Nor is it an absolute condition that the substance of the bag should be quite impervious to the gas or confined air; though such a defect, by allowing the partial escape of the buoyant fluid, must inevitably diminish the vigour and abridge the duration of the power of the balloon's ascent. This power is evidently the excess of the weight of an equal bulk of atmospheric air above the aggregate weight of the included gas, joined to that of the bag, and of all its appendages: in other words, the final power of ascent is the difference between the weight of the included gas and of that of an equal volume of external air, further diminished by the weight of the whole apparatus. But supposing the form of the balloon to remain the same, this counteracting load, as it depends on the quantity of surface contained in the bag, must be proportioned to the square of the diameter; whereas the difference between the internal and external volume of fluid, which constitutes the whole of the buoyant force, increases in a faster ratio, being proportioned to the capacity of the bag, or the cube of its diameter. It hence follows, that however small the excess may be of the specific gravity of the external air above that of the collected fluid, there must always exist some corresponding dimension which would enable a balloon to mount in the atmosphere.
The theory of aeronautics, considered in its detail, includes three distinct things: first, the power of a balloon to rise through the air; second, the velocity of its ascent; and, third, the stability of its suspension at any given height in the atmosphere. These points we shall examine separately.
1. The buoyant force of balloons. Since balloons in their shape generally approach to the spherical form, it will be more convenient to ground our calculations on that figure. A globe of common air at the level of the sea, and of the mean density and temperature, is found to weigh about the 25th part of a pound avoirdupois. Consequently, if a perfect vacuum could be procured, a balloon of ten feet diameter must rise with a force of 40 pounds; one of twenty feet diameter, with that of 320 pounds; and a balloon of thirty feet in diameter would mount in the atmosphere with the power of 1080 pounds:—thus augmenting always in the ratio of the cube of the diameters. But air expands by heat about the 450th part
Aéronautics. of its bulk for each degree on Fahrenheit's scale. Supposing, therefore, that the air included within the bag were heated 50 degrees, which is as much perhaps as could be well supported, it would follow that one ninth part of this fluid would be driven out by the warmth, and consequently, that the tendency of the balloon to rise upwards would be equal only to the ninth part of the entire power of ascension. Were it possible to maintain a heat of 75 degrees within the balloon, the buoyant force would yet not exceed the sixth part of the absolute ascensional power.
from humidity: The dilatation which the presence of humidity communicates to air will, during fine weather in this climate, amount generally to one eighteenth part, though it may sometimes reach to more than the double of this quantity. But, in the tropical regions, such dilatation will commonly exceed the twentieth part of the volume of fluid. Hence moist air thrown into a bag, likewise wetted, and sufficiently large, would cause it to rise in the atmosphere. To succeed, however, in this way, the balloon constructed of coarse linen would require enormous dimensions; not less than three hundred feet in diameter.
from heat joined to moisture: But it is the union of heat and moisture that gives to air the greatest expansion. The white smoke with which the balloons are filled on Montgolfier's plan, was found, by computation, to be at least one-third specifically lighter than the external air. This purer sort of smoke is scarcely any thing but air itself charged with vapour, being produced by the burning of chopped straw or vine twigs in a brasier, under the orifice of the bag. It would have required no fewer than 150 degrees of heat alone to cause the same extent of rarefaction.
Smoke balloons. We have therefore sufficient data for calculating the buoyant force of the common fire, or rather smoke balloons. This force, being estimated about 12½ pounds avoirdupois when the diameter of the bag is ten feet, would amount to 1562½ pounds if the diameter were fifty feet, and to 12,500 pounds if it were a hundred feet. The weight of the linen case may be reckoned at two-fifths of a pound for a sphere of one foot in diameter. Consequently, a balloon of ten feet diameter would, without its appendages, weigh 40 pounds; one of fifty feet diameter, 1000 pounds; and one of a hundred feet diameter, 4000 pounds. Such a balloon of ten feet diameter would need 27½ pounds to make it rise, but one of fifty feet diameter would ascend with a force of 562½ pounds, and one of a hundred feet diameter would exert an ascending power of not less than 8500 pounds. There is besides to be deducted the weight of the cordage, the car, the ballast, and the passengers. It would require, on these estimates, a diameter of 33½ feet, to procure merely an equilibrium between the weight of the canvass and the buoyant force of the rarefied air.
The hydrogen gas obtained from the action of dilute sulphuric acid upon iron filings is only six times lighter than atmospheric air; but the gas evolved during the solution of zinc in that acid is not less than twelve times lighter than the standard fluid. The ordinary way of examining the specific gravity of the different gases requires a very delicate operation of weighing with the most exquisite balance; a serious difficulty, which long retarded our knowledge of their comparative densities. In one of the notes to his Treatise on Heat, Professor Leslie has pointed out a very simple method, founded on the principles of pneumatics, for discovering the relative specific gravities of the æriform fluids. This consists in observing the time that a given portion of the gas, under a determinate pressure, takes to escape through a very small aperture. The density of the gaseous fluid must be in-
versely as the square of the interval elapsed. Thus, the hydrogen gas procured from zinc, but without any depuration, was found, under a pressure of the same column of water, to flow thrice as fast as atmospheric air. This experiment is very striking, and requires no more apparatus than a cylindrical glass jar, open below, and surmounted by a cap terminating in a fine tubular orifice.
On a very moderate supposition, therefore, and after Balloons making every allowance for imperfect operation, we may with consideration the hydrogen gas which fills a balloon as six-drogengas times lighter than the like bulk of common air. Consequently, such a balloon must exert five-sixths of the whole buoyant force corresponding to its capacity, or will have a tendency to mount in the atmosphere, that is equal to the thirtieth part of a pound avoirdupois for a globe of one foot diameter. A spherical balloon of fifteen feet diameter would hence have a buoyancy of 112½ pounds; one of thirty feet, 900 pounds; and one of sixty feet no less than 7200 pounds. But thin silk, varnished with caoutchouc or elastic gum, to render it impervious to air, is found to weigh only the twentieth part of a pound when formed into a globe of one foot diameter. A silk balloon of fifteen feet diameter would hence weigh 11½ pounds; one of thirty feet, 45 pounds; and one of sixty feet diameter, 180 pounds. Wherefore, the power of ascension exerted by such balloons would, in pounds avoirdupois, be respectively 101½, 855, and 7020. It follows, also, that a balloon of a foot and a half in diameter would barely float in the atmosphere, the weight of its varnished silk being then exactly balanced by the buoyant effort of the body of hydrogen gas.
But the calculations now given would in strictness require a small modification. The weight of the bag and of all the appendages must evidently compress the included gas, and thereby render it in some degree denser. To compute this minute effect, we have only to consider, that the pressure of a column of atmosphere, at the mean temperature, and near the level of the sea, is 1632 pounds, on a circle of a foot diameter. Thus, in the large balloon of sixty feet diameter, if we suppose the whole load to have been 6000 pounds, the compression of the bag would only amount to five-thirds of a pound for each circle of a foot diameter in the horizontal section, or correspond to the 979th part of the entire pressure of the atmosphere. But the weight of the confined gas being 1200 pounds, its buoyancy must have suffered a diminution of somewhat more than a pound, or from the encumbrance opposed to it. This correction is therefore a mere theoretical nicety, which may be totally disregarded in practice.
II. The next circumstance to be considered in aéro-Celerity of nautics is, the celerity with which balloons make their ascent. It is obvious that the efficient power of ascension, or the excess of the whole buoyant force above the absolute weight of the apparatus, would, by acting constantly, produce always an accelerated motion. But this acceleration is very soon checked, and a uniform progress maintained, by the increasing resistance which the huge mass must experience in its passage through the air. The velocity which a balloon would gain from unobstructed acceleration must, from the theory of dynamics, be to that which a falling body acquires in the same time, as the efficient buoyancy is to the aggregate weight of the apparatus and of the contained fluid. Thus, if the balloon were to rise with a force equal to the eighth part of its compound weight, the celerity resulting from a constant acceleration would be expressed by multiplying four feet into the number of seconds elapsed since it was launched into the air. Its accelerating advance, however, being opposed,
the balloon may to all appearance attain, though still affected with partial oscillations, the final velocity in perhaps little more than double the time required without such obstruction.
This final velocity, or the velocity at which the ascent becomes uniform, the resistance from the air being then equal to the efficient buoyancy of the balloon, is easily calculated. The resistance a circle encounters in moving through any fluid in the direction perpendicular to its plane, is measured by the weight of a column of that fluid, having the circle for its base, and an altitude equal to the height from which a heavy body in falling would acquire the given celerity. But near the level of the sea, and at the mean temperature, a column of atmospheric air 17 feet high, and incumbent on a circle of one foot diameter, weighs a pound avoirdupois; which is therefore the resistance that such a circle would suffer if carried forwards with the celerity of 33 feet each second. According to the same theory, however, which we owe to the sagacity of Newton, the resistance of a sphere is just the half of that of its generating circle, and consequently a velocity of 46 feet in a second through the air would, in ordinary cases, create a resistance of one pound to a ball of one foot diameter. In other circumstances, the quantity of resistance must be proportional to the squares of the velocities and of the diameters. Whence, if the buoyant force were always the same, the velocity of the ascent of a balloon would be inversely as its diameter.
Suppose a balloon to have thirty feet in diameter, and an ascensional power of 100 pounds. This effort is evidently the same as the ninth part of a pound for a globe of a foot diameter, and would therefore be counterbalanced by the resistance corresponding to a velocity of 46 divided by 3, the square root of 9, or 15 feet each second. The balloon would therefore reach the altitude of a mile in about six minutes. Its accelerating force being only the sixteenth part of its total weight, it might have acquired the uniform motion of ascent in twenty seconds, or before it had attained the height of 200 feet. This example differs very little from reality, and the method of computation will easily be transferred to other cases.
But the resistance of the air assigned by theory is, from the circumstances omitted in the simplification of the problem, generally somewhat less than the results of observation. In low velocities this difference amounts seldom to the fifth part of the whole effect; but in the high velocities it increases considerably, exceeding even the third part in certain extreme cases. From the numerous and accurate experiments of Dr Charles Hutton, we may, however, deduce a simple formula for expressing the terminal velocity of balloons, or the celerity of their uniform ascent. Let denote the diameter of the balloon in English feet, and its ascensional power, measured in pounds
avoirdupois; then will very nearly represent in feet
the velocity each second of its regular ascent, or that velocity which would cause a resistance from the air precisely equal to the buoyant force. Or, to express the rule in words: As the diameter of the balloon in feet is to the constant number 40, so is the square root of the ascensional power in pounds to the terminal or uniform velocity of ascent each second. To illustrate the application of the formula by an easy example: suppose the balloon to have a diameter of 60 feet, with an accelerating power of 144 pounds; the corresponding rate of uniform ascent
becomes , or , that is, 8 feet each second, or about a mile in eleven minutes.
III. The last point which demands attention in aëro-
nautics, is, the stability of the suspension of a balloon at any
given height in the atmosphere. The circumstances which
might regulate or determine that stability, requiring some
little exercise of thought, have been commonly neglected,
and very seldom examined with due care. It will be pro-
per to consider, first, the fire or smoke balloons, and, second-
ly, the balloons filled with hydrogen gas.
1. The warm humified air of the balloon constructed
after Montgolfier's plan suffering less external compres-
sion as it approaches the upper strata of the atmosphere,
must at the same time necessarily expand, and partly
escape by the orifice above the brasier. The weight of the
included fluid, and that of the part expelled, constituting
its buoyant force, will hence be reduced, in proportion to
the diminished density of the medium in which it floats.
The balloon will continue to ascend till its enfeebled buoy-
ancy is no longer able to support the incumbent load. At
the height of a mile above the surface, the power of ascen-
sion would be diminished rather more than one fifth part;
but at an altitude of three miles and a half it would be
reduced to one-half. At the ordinary temperature, this
buoyancy would suffer a reduction of the hundredth part
for each ascent of 278 feet. Resuming the data formerly
stated, and supposing the balloon to have a spherical shape,
its actual power of ascension, estimated in pounds avoir-
dupois, will be denoted by , where signifies the dia-
meter in feet, or the cube of the diameter divided by the
constant number 80. If express the ratio of atmo-
spheric density at the surface and at any given height,
then will denote the diminished buoyant force at
that altitude.
We shall select, for example, a balloon of 100 feet dia-
meter, which is one of the largest dimensions ever ac-
tually constructed. Near the level of the sea, and at the
ordinary temperature, its power of ascension would be
12,500 pounds; but at the height of 8000 feet, or somewhat
more than a mile and a half, when the density is diminished
one-fourth, or that power becomes reduced to
, or 9375 pounds, being a deficiency of 3125
pounds. On the supposition that the balloon was at first so
much loaded as to rest just suspended at the ground, a bal-
last of 3125 pounds must have been thrown out, to make it
rise to the altitude of a mile and a half. Hence also the
rejection of 125 pounds would have been sufficient to give
the balloon an elevation of 278 feet. For the same reason,
10 pounds of ballast heaved out would raise it 22 feet at
the surface, 29 feet at the height of a mile and a half, and
44 feet at that of three miles and a half.
2. The stability of the suspension of balloons filled with
hydrogen gas must depend on principles which are very charged
different and less marked. In these aeronautic machines, with hy-
drogen gas, after the gas has been once introduced, it is closely shut
up; and therefore, having constantly the same absolute gas
weight, it should likewise, in all situations, exert the same
buoyant force. Hence, if the balloon were capable of inde-
finite extension, it would still continue its ascent through
unbounded space. The determinate capacity of the bag
alone can oppose limits to its rise in the atmosphere. The
upper strata being rarer than those below, will have less
power to keep any given bulk suspended; and the actual
buoyancy being diminished from that cause, the balloon
will find its station at a corresponding height in the dif-
fuse medium. But this diminution of the buoyant force,
Aéronautics. and the consequent increase in the density of the hydrogen gas, must necessarily be confined within very moderate limits, otherwise the thin silk case would be torn to shreds by the expansive efforts of the imprisoned fluid. A safety-valve is accordingly placed at the top of the balloon, calculated to give vent to the gas before the distension has become such as to endanger the bursting of the case.
should not be completely filled; A balloon should not at first be filled completely with hydrogen gas, but allowed to begin its ascent in a flaccid state. As it mounts into the rarer atmosphere, it will gradually swell, till it has attained its full distension, when the safety valve may come to act. But such dissipation of the gas ought, by a previous arrangement, to be as much as possible avoided. If the balloon were intended to rise to the height of four miles, it would not be requisite to fill more than half its capacity with the elastic fluid. To push the charge any farther in this case, would only occasion a superfluous waste of materials. By throwing out part of his ballast, the aéronaut may raise himself higher; and by opening the valve to permit some of the imprisoned gas to escape, he may descend again: but both those expedients are attended by a wasteful expenditure of power.
unstable when flaccid. It is evident that a balloon can have no stability of equipoise, so long as it remains in a loose or flaccid state. The slightest action would then be sufficient to make it rise or fall, since, under such circumstances, any change of its station could not in the smallest degree affect the measure of its buoyant force. The general elevation to which the balloon will ascend must be determined by its quantity of ballast, conjoined with the regulation of the safety-valve; but the strain of the silk case itself would be sufficient to confine the ascent within certain limits, and to procure the stability of the floating mass. Thus, if a balloon fully distended had yet a slight disposition to rise, the imprisoned gas, suffering more and more compression as it gradually ascends, would become proportionally denser, and therefore lose a corresponding part of its previous buoyancy. An equilibrium would hence soon obtain, which must arrest the floating machine at a determinate height in the atmosphere.
Mode of adjusting balloons. Suppose a balloon to be capable, without any danger of bursting, of sustaining an expansion equal to the hundredth part of the elasticity of the included fluid; the whole buoyancy would, by such an alteration, be diminished one five hundredth part, or this floating machine would subside 55 feet near the surface, and sink proportionally more in the upper regions. To produce the effect, it would only be requisite to throw common air into the bag, without suffering any portion of the hydrogen gas to escape. On this principle Meusnier, an ingenious French chemist, very soon after the first discovery of balloons, proposed to regulate with nicety their ascent and position of equilibrium in the atmosphere. The mode which he suggested was, to place within the principal balloon a much smaller one, to be filled occasionally with common air by help of bellows, or emptied again by opening an exterior valve. The aéronaut would thus have it in his power, without expending the charge of hydrogen gas, either to sink gently through a short space, or to rise again at will, by inflating the inner balloon, or allowing it to collapse. The adjustment of the height of a balloon could hence be managed with great precision.
The command possessed by the aéronaut of raising or depressing his machine at pleasure, might afford him the means of influencing the direction of its course. From the various motions of the several ranges of clouds, we may infer that different currents exist at the same time in the atmosphere. The aéronaut has, therefore, in his as-
cent, only to seek the current best suited to his purpose, and, taking his station in that stratum, to commit his flimsy vessel to the guidance of the stream.
Aéronautics. Any other attempts to direct or control the flight of a balloon are altogether fallacious. Since it is carried along applying with the swiftness of the wind, no rudders or sails can have any action whatever. The aéronaut might fancy himself to float in a perfect calm, unless he chances to encounter irregular currents. The application of oars may turn a balloon, but can have no sensible effect in diverting or impelling its course. How vastly disproportionate is the force of the human arm to the overwhelming pressure of the wind against so huge a machine! To adapt machinery under these circumstances would be preposterous, and to look for help from such a quarter is visionary in the extreme. It must be admitted, however, that after a balloon has once gained its station of equilibrium, or passively floats in the air, the vigorous action of broad vanes, downwards or upwards, might serve to raise or depress the machine through a small space. Thus, a vertical force, exerted equal to nine pounds, would lift a balloon of thirty feet in diameter 278 feet higher. The application of ballast is hence infinitely preferable to any such bulky and unmanageable apparatus.
At the period where we left our narrative, the principles on which a balloon could be constructed were therefore pretty generally known to men of science. But to reduce these principles to complete effect, was still an enterprise of the most dazzling kind. This experiment seemed unfit for a cabinet or a laboratory, and it could succeed only on a large scale, exposed to the gaze of the multitude. Without the toil of investigation, or indeed any exercise of thought, all the world might witness the result, and admire the magnificent spectacle which it would present. This triumph over matter was at length achieved by the skill and perseverance of Stephen and Joseph Montgolfier, sons of the proprietor of an extensive and very celebrated paper manufactory established at Annonay, on the banks of a rivulet which flows into the Rhone, near forty miles below Lyons. These remarkable persons, though bred in a remote provincial town, possessed in a high degree ingenuity and the spirit of observation. Without having the benefit of a liberal education, their active curiosity had led them to acquire a more extensive and accurate stock of knowledge than is usually found in the same condition of life. Stephen was more attached to mathematics, but Joseph directed his studies chiefly to chemistry and natural philosophy. They were associated in business with their father, who passed his quiet days, like a patriarch, amidst a large family, and a numerous body of workmen, and reached the very advanced age of 93. Of the younger brother, who survived the other, and lived to make the very valuable yet much neglected discovery of the hydraulic ram, we may venture to speak from personal acquaintance. He was a man of great modesty and simplicity of character, yet firm and undaunted, of a calm and sedate aspect, tall and athletic in his person, and of a swarthy complexion, not unlike the celebrated Mr Watt, whom he resembled in some other particulars of his fortune. He was too speculative, perhaps, to succeed in the details of business; for, after trying various schemes of improvement, he quitted his paper manufactory and repaired to the capital, where he obtained a situation of trust under the late imperial government, at the chamber of models, as inspector of patents and internal improvements. In 1809 he had a stroke of palsy, which induced him to resort to the waters of Bourbonne; but receiving no benefit from them, he gladly preferred those of Balaruc,
Aéronautics. near his old friends, where he died on the 26th of June in the following year, at the age of 60.
Their successive experiments. The two brothers, who were accustomed to form their plans in concert, had long contemplated the floating and ascent of clouds in the atmosphere. It seemed to them, that a sort of fictitious cloud, formed of very thin vapour, inclosed in a light bag of immense size, would mount to the higher regions. In pursuit of this idea, they selected a fluid specifically lighter than atmospheric air; and, accordingly, introduced hydrogen gas into large bags of paper and of thin silk, which rose up, as had been expected, to the ceiling, but fell down in a few seconds, owing to the rapid escape of the gas through the cracks and pores of the case. This great facility with which hydrogen gas makes its way through any substance of a loose and incompact texture, is partly due to its extreme fluidity, but is chiefly occasioned by its strong and obstinate attraction for common air. The mode of preventing, or at least checking that escape, by the application of a proper varnish, was yet unknown. The prospect of overcoming the difficulty was so discouraging, that our experimenters had recourse to another scheme, more analogous to their original ideas, and it rewarded their continued efforts with the most complete success. In the month of November 1782, Joseph Montgolfier, happening, in the course of his frequent excursions, to be then at Avignon, procured a small silk bag, of the form of a parallelopipedon, open below, like a lady's hoop, and having a capacity of about forty-five cubic feet; under its orifice he burnt some paper, and saw, with inexpressible transport, the bag quickly swell, and mount rapidly to the height of seventy-five feet, where it remained till by cooling it lost its buoyancy. Returning to Annonay, he communicated the happy result to his brother, and it was resolved by them to prosecute the experiment on a large scale. Having provided a large quantity of coarse linen, they formed it into the shape of a globe, about thirty feet in diameter, which they lined with paper. On lighting a fire within its cavity, to warm and expand the air, they had the delightful satisfaction of seeing the bag ascend with a force equivalent to 500 pounds.
First public ascent of a balloon. It was very natural that the brothers should now desire an occasion for exhibiting this grand experiment in their native town. They invited the members of the provincial meeting of the states of the Vivarnis, then assembled at Annonay, to witness the first public aerial ascent. On the 5th June 1783, amidst a very large concourse of spectators, the spherical bag or balloon, consisting of different pieces of linen, merely buttoned together, was suspended from cross poles; two men kindled a fire under it, and kept feeding the flames with small bundles of chopped straw; the loose bag gradually swelled, assuming a graceful form, and in the space of five minutes it was completely distended, and made such an effort to escape, that eight men were required to hold it down. On a signal being given, the stays were slipped, and the balloon instantly rose with an accelerating motion, till it reached some height, when its velocity continued uniform, and carried it to an elevation of more than a mile. All was admiration and transport. Amidst the shouts of unbounded acclamation, the progress of the artificial cloud retiring from sight arrested every eye. It was hurried along by the wind; but, its buoyant force being soon spent, it remained suspended only ten minutes, and fell gently in a vineyard, at the distance of about a mile and a half from the place of its ascension. So memorable a feat lighted up the glow of national vanity, and the two Montgolfiers were hailed and exalted by the spontaneous impulse of their fellow-citizens.
Of this splendid experiment a very hasty and imperfect
account was transmitted to Paris, and quickly circulated over Europe. In those halcyon days, during the transient calm of political tumults, and the happy absence of all military events, the prospect of navigating the atmosphere excited a very general ferment, and engrossed the conversation of all ranks. Yet the tale appeared so extraordinary as to leave some doubts of its veracity. In many places, and especially in this country, the more ignorant class of men, and those who affected superior wisdom, both agreed in considering the relation of Montgolfier's discovery as nothing but an imposition practised on the public credulity. To dispel the suspicions which infected the subject, it was necessary to repeat the experiment in every large capital.
When the intelligence of the first ascent of a balloon reached St Petersburg, it found the venerable Euler in a state of great debility, worn out with years and unremitting intellectual toil. Having lost, in the middle of his career, the sight of an eye, he had been for several years visited with total blindness. But in this afflicting situation his mind was still entire, and found delightful exercise in his former habits of calculation. It was in training a domestic to act as his amanuensis, that this great genius now condescended to dictate, in the German language, to his humble pupil, a work of the highest merit, The Elements of Algebra. During his last illness, Euler made an expiring effort, and applied his favourite analysis to determine the ascending motion of a balloon. He dictated the preliminary steps of the problem to one of his grandchildren; but the hand of death was already stretched over the patriarch;—no farther could he proceed with his investigation;—and composing himself for nobler scenes, he calmly expected the moment of dissolution.
The virtuosi at Paris were eager to repeat the experiment of the ascension of a balloon. M. Faujas de St Fond, an active and zealous naturalist, set on foot a subscription for defraying the expense, which was soon filled up. The construction of the machine was intrusted to the skill of two brothers of the name of Robert, under the superintendence of M. Charles, an ingenious lecturer in natural philosophy. It had at first been proposed merely to copy the process of Montgolfier, but Charles preferred the application of hydrogen gas; a resolution which afterwards occasioned much difficulty and delay. The balloon consisted of thin silk or tiffany, varnished with a solution of elastic gum, disposed into a globular shape, of about thirteen feet in diameter. The hydrogen gas was procured from the action of dilute sulphuric acid upon iron-filings, and was introduced through leaden pipes. But this gas, being rapidly formed, without having been made to pass through a body of cold water, entered the cavity of the balloon excessively hot, and charged with acid fumes, which afterwards condensed against the inside of the bag, injuring its texture, and loading it with superfluous humidity. Not fewer than 500 pounds of sulphuric acid were used, and twice this weight of iron-filings; yet several days were spent in abortive attempts to fill the balloon completely. At last it rose, and was kept suspended at the height of 100 feet above the ground. In this state it was conveyed with acclamations to the Place des Victoires, where it rested, and underwent some repair. About midnight it was thence transported in silent procession, preceded by torch-lights, and guarded by a detachment of horse and foot soldiers, to the Champ de Mars, at the distance of near two miles. The few passengers found at that still hour on the streets gazed with astonishment at the floating mass; and the very coachmen, filled with a sort of awe, respectfully saluted it as they passed.
Next day, being the 27th of August 1783, an immense
concourse of people covered the Champ de Mars, and innumerable spectators had planted themselves along the banks of the Seine and the amphitheatre of Passy. By three o'clock every avenue was filled with carriages, and all the beauty and fashion of Paris flocked towards the Ecole Militaire. The preparations being finished, a cannon was discharged as the signal of ascent. The balloon, liberated from its stays, shot upwards with such rapidity as in two minutes to reach, according to calculation, the height of 3000 feet, where it seemed lost in a dark cloud. It reappeared at a greater elevation, but was soon obscured again amidst other clouds; and after performing a flight of about fifteen miles in the space of three quarters of an hour, it sunk to the ground in a field near Ecouen, where the peasants secured it, having noticed a rent in the upper part of the bag, to which its fall might be imputed. The success of the experiment was complete. The incredulous were sadly mortified; but every minor reflection was drowned in the tumult of excessive joy and exultation. It began to rain immediately after the balloon was launched, yet this unlucky circumstance had no effect to abate the curiosity of the spectators. Regardless of the torrents that fell, they were wholly absorbed in following with eager gaze the progress of the machine through the air. Even elegant ladies, dressed in their finest attire, stood exposed, looking intently the whole time, and were drenched to the skin. This small balloon weighed only thirty pounds, and had at first a buoyant force of forty pounds avoirdupois. If we employ the formula before given, the terminal velocity would be feet in a second, or 1168 feet each minute; which appears to correspond very well with fact.
About this time Joseph Montgolfier visited Paris, and was invited by the Royal Academy of Sciences to repeat his experiment of Annonay on a larger scale. He constructed, with coarse linen and a paper lining, a balloon of a pear shape, and about 43 feet wide and 75 feet high. The smoke of fifty pounds of dry straw, in small bundles, joined to that of twelve pounds of wool, was found sufficient to fill it in the space of ten minutes. The bag duly swelled, and made an effort to rise equivalent to the weight of 500 pounds; but being reserved for exhibition the next day, it was totally destroyed, by its exposure during the night to incessant and violent rain. It became necessary, therefore, to prepare another balloon; and such was the expedition of the artist, that in five days he got the whole completed. Early on the morning of the 19th of September, it was placed upon an octagon scaffold, in front of the palace of Versailles. It had a very showy appearance, being painted with ornaments in oil colours. By ten o'clock the road from Paris was crowded with carriages of all descriptions. Every person of any note or fashion hurried from the metropolis to view the experiment; ladies of distinguished rank filled the windows; and the spacious courts and walks, and even the tops of the houses, were covered with impatient spectators. The royal family and their attendants came forth, and examined the details of the apparatus. About one o'clock the discharge of a mortar gave notice that the filling of the balloon was to commence. In eleven minutes another discharge announced that it was completely inflated; and on the third discharge of the mortar, the cords were cut, and the balloon instantly liberated. After balancing at first in a moment of anxious expectation to the spectators, it rose majestically, in an oblique direction, under the impulse of the wind, till it reached the height of 1500 feet, where it appeared for a while suspended; but in the space of eight minutes it dropped to the ground, at the distance of two
miles from the point of its ascent. A sheep, a cock, and a duck, which had been put into the basket, the first animals ever carried up into the air, were found perfectly safe and unhurt by the journey, and the sheep even feeding at perfect ease. See Plate II. for a view of this balloon and the following ones.
This successful experiment encouraged Montgolfier to prepare, on a more solid construction, another balloon, of a spheroidal form, 45 feet wide and 75 feet high. While it was filling with smoke, Pilatre de Rozier, a young naturalist of great promise, and full of ardour and courage, leaped into the car, and was borne up to the height of 300 feet, where he continued some minutes suspended, the balloon being held down by long cords till it gently descended. The dangers of navigating the balloon being thus brought to a more correct estimate, it was resolved speedily to attempt the daring but sublime experiment. The badness of the weather, however, at this late season of the year, made the project be deferred several days. At last, on the 21st of November, every thing was ready for the ascent in the spacious gardens of the chateau of Muette, belonging to the court of the Dauphin. The sky had a lowering aspect, being loaded with heavy clouds, driven about by irregular winds. But the adventurers were not to be easily discouraged. After a first trial, Makes the which had nearly proved fatal to them, the balloon was first aerial again filled; and Rozier, with the marquis d'Arlandes, a voyage. major of infantry, who had volunteered to accompany him, took their seats in the car, having a store of ballast, and a provision of straw to supply the fire. About two o'clock the machine was launched, and it mounted with a steady and majestic pace. Wonder, mingled with anxiety, was depicted in every countenance; but when, from their lofty station in the sky, the navigators calmly waved their hats, and saluted the spectators below, a general shout of acclamation burst forth on all sides. As they rose much higher, however, they were no longer discernible by the naked eye.
..... in the surging smoke
Uplifted spurn the ground; thence many a league,
As in a cloudy chair ascending, ride
Audacious.
This balloon soared to an elevation of more than 3000 feet, and traversed, by a circuitous and irregular course, the whole extent of Paris, whose gay inhabitants were all absorbed in admiration and amazement. A curious circumstance occurred during the passage of the floating mass: to the gazers planted on the towers of the metropolitan church of Notre Dame, it chanced to intercept the body of the sun, and thus gave them, for a few seconds, the spectacle of a total eclipse. It has been alleged, that when the balloon had reached so high that the objects on earth were no longer distinguishable, the marquis d'Arlandes began to think that his curiosity and ambition were sufficiently gratified. He was therefore anxious to descend, and murmured against his companion, who still kept feeding the fire. At last, on hearing some cracks from the top of the balloon, and observing holes burning in the sides, the major became outrageously alarmed at his imminent danger, and applying wet sponges to stop the progress of combustion, he compelled the savant to desist from his officious operations. As they now descended too fast, however, M. d'Arlandes was not less anxious and diligent in throwing fresh straw upon the fire, in order to gain such an elevation as would clear the different obstacles. The navigators dexterously avoided the lofty buildings of Paris, by supplying fuel as occasion required; and, after a journey of 20 or 25 minutes, they safely alighted beyond the Boulevards, having described a track of six miles.
Such was the prosperous issue of the first aerial navigation ever achieved by mortals. It was a conquest of science which all the world could understand; and it flattered extremely the vanity of that ingenious people, who hailed its splendid progress, and enjoyed the honour of their triumph. The Montgolfiers had the annual prize of six hundred livres adjudged to them by the Academy of Sciences; the elder brother was invited to court, decorated with the badge of St Michael, and received a patent of nobility; and on Joseph a pension was bestowed, with the further sum of forty thousand livres, to enable him to prosecute his experiments with balloons.
The facility and success, however, of the smoke or fire balloons appeared to throw into the shade the attempts made by the application of hydrogen gas. M. Charles, the promoter of this plan, was keenly reproached by M. Faujas de St Fond, for departing from the method practised by the original inventor; and he was, moreover, with his associates the Roberts, held up to public derision in the smaller theatres of Paris. To silence the cavils and insinuations of his antagonists, he resolved, therefore, on making some new efforts. A subscription was opened to defray the expense of a globe twenty-eight feet in diameter, and formed of tiffany, with elastic varnish. After repeated accidents and delays, this balloon was planted, on the 1st of December 1783, at the entrance of the great alley of the Tuilleries; and the diffuse fluid was this time introduced into it from a sort of gasometer. The dilute sulphuric acid and the iron-filings being put into wooden casks, disposed round a large cistern, the gas was conveyed in long leaden pipes, and made to pass through the water under a glass bell plunged in it. The whole apparatus cost about L.400 sterling, one-half of which was expended on the production of the gas alone. An immense concourse of spectators had collected from all parts. The discharge of a cannon at intervals announced the progress in filling the balloon. To amuse the populace, and quiet their impatience, M. Montgolfier was desired to let off a small fire-balloon, as a mark of his precedence. At last, the globe being sufficiently inflated, and a quantity of ballast, consisting of small sand bags, lodged in the car, leaving only 22½ pounds for the measure of the buoyant force, M. Charles and Robert placed themselves in the appended boat or car, and the machine was immediately disengaged from its stays. It mounted with a slow and solemn motion. According to the formula given, the terminal velocity of ascension must have been only about 400 feet each minute, or at the rate of somewhat less than five miles in the hour. "The car, ascending amidst profound silence and admiration," to borrow the warm and exaggerated language of the reporter, "allowed, in its soft and measured ascent, the bystanders to follow with their eyes and their hearts two interesting men, who like demigods soared to the abode of the immortals, to receive the reward of intellectual progress, and carry the imperishable name of Montgolfier. After the globe had reached the height of 2000 feet, it was no longer possible to distinguish the aerial navigators; but the coloured pennants which they waved in the air testified their safety and their tranquil feelings. All fears were now dissipated; enthusiasm succeeded to astonishment; and every demonstration was given of joy and applause." The balloon, describing a tortuous course, and rising or sinking according to the fancy of its conductors, was, after a flight of an hour and three quarters, made to alight on the meadow of Nesle, about twenty-five miles from Paris. For the space of an hour, the buoyancy of the machine had been sensibly augmented by the sun's rays striking against the surface
of the bag, and heating up the contained gas to the temperature of 55 degrees by Fahrenheit's scale. Aéronau-
tics.
After this prosperous descent, the globe, though become rather flaccid and loose by its expenditure, yet still retained a great buoyant force when relieved from the weight of the travellers. The sun had just set, and the night was beginning to close; but M. Charles formed the resolution of making alone another aerial excursion. His courage was rewarded by the spectacle of one of the most novel and enchanting appearances in nature. He shot upwards with such celerity as to reach the height of near two miles in ten minutes. The sun rose again to him in full orb; and, from his lofty station in the heavens, he contemplated the fading luminary, and watched its parting beams, till it once more sunk below the remote horizon. The vapours rising from the ground collected into clouds, and covered the earth from his sight. The moon began to shine, and her pale rays scattered gleams of various hues over the fantastic and changing forms of those accumulated masses. This scene had all the impressive solemnity of the true sublime. No wonder that the first mortal eye that ever contemplated such awful grandeur could not refrain from shedding tears of joy and admiration. The region in which M. Charles hovered was now excessively cold; and as he opened the valve occasionally during his ascent, to prevent the violent distension of the balloon, the hydrogen gas, not having time to acquire the temperature of the exterior air, rushed out like misty vapour, with a whistling noise. But prudence forbade the voyager to remain long at such an elevation, while darkness was gathering below. He therefore descended slowly to the earth, and, after the lapse of 35 minutes, alighted near the wood of Tour du Lay, having, in that short interval, travelled about nine miles.
This balloon, with its passengers and ballast, weighed at first 680 pounds; but, notwithstanding the care taken in filling it, the hydrogen gas must have been mixed with a large proportion of common air, since it was only 5½ times lighter than this fluid. The barometer, which stood at 29.24 English inches at the surface of the ground, subsided to 20.05 at the greatest elevation to which M. Charles had reached. This gives by calculation an altitude of 9770 feet. The thermometer, which was at 41° by Fahrenheit's scale at the first ascent, fell to 21° at the highest flight; giving a difference of one degree for every 488½ feet of ascent.
The next voyage through the air was performed in the largest balloon ever yet constructed. The elder Montgolfier had been persuaded to open a subscription at Lyons for the sum of L.180 sterling, to construct an aeronautic machine capable of upholding a great weight, and of carrying a horse or other quadruped. It had an elongated shape, 109 feet wide and 134 feet high, and was formed of two folds of linen, having three layers of paper laid between them, and quilted over with ribands. It showed at first enormous buoyant power. A truss of straw, moistened with spirit of wine, was found, when set on fire, to yield humid smoke sufficient to inflate the balloon, and the burning of five pounds weight of alder faggots kept it in full action. Though loaded with a ballast of eighteen tons, it yet lifted up six persons from the ground. Unfortunately, it was very much damaged one night, in consequence of being exposed to rain, frost, and snow. However, on the 19th of January 1784, the balloon was charged in seventeen minutes, by the combustion of 550 pounds of alder. Joseph Montgolfier, accompanied by the ardent Pilatre de Rozier, and four other persons of note, with the proper ballast, took their seats in a wicker gallery, and were launched into the atmosphere. They
Aéronautics. manoeuvred over the city of Lyons, and near the course of the Rhine, for the space of forty minutes; but a large rent having been observed in the upper part of the balloon, they were compelled to descend abruptly, though without any further accident.
The difficulties and dangers of aerial navigation being at length surmounted, the ascents of balloons were now multiplied in all quarters. It will therefore be sufficient henceforth to notice very succinctly some of the more distinguished attempts of that kind.
Andreani. The Chevalier Paul Andreani of Milan had a spherical balloon, of 70 feet in diameter, formed after Montgolfier's plan, at his own charge, in which, accompanied by two companions, he ascended from that capital on the 25th of February 1784. The machine rose to the height of 1300 feet; but after having described, in twenty minutes, a very circuitous track, it settled upon a large tree, from which however the voyagers, by applying fresh fuel, extricated themselves, and alighted on clear ground, without receiving any hurt.
Blanchard. On the 2d of March Blanchard, who had been for some years before occupied with the chimerical project of flying in the air, and who fancied that the same principles and contrivances might be applied to direct the motion of balloons, mounted alone, and with great intrepidity, at Paris, in a silk balloon 40 feet in diameter, constructed by subscription, and filled with hydrogen gas. He darted rapidly to the height of above a mile, and after being driven about by cross winds for an hour and three quarters, he descended in the plain of Billancourt.
Fleurant and Thiblé. On the 28th of June in the same year, an ascent was made at Lyons before the King of Sweden, who then travelled under the name of Count Haga, with a fire-balloon, having somewhat of a pear shape, and 75 feet in height. Two passengers, M. Fleurant and a young lady, Madame Thiblé, the first female that ever adventured on such a daring voyage, entered the car, and ascended with great velocity. In four minutes the noise of the multitude was no longer audible, and in two more the eye could not distinguish them. It was inferred, from a trigonometrical calculation, that they had reached the altitude of 13,500 feet. Their flag, with its staff of 14 pounds weight, being thrown down, took seven minutes to fall to the ground. The thermometer had dropped to 43° on Fahrenheit's scale; and to the sensation of cold which they felt was joined that of a ringing in the ears. Different currents were found to occupy distinct strata of the atmosphere; and in passing from one stratum to another, the balloon was affected by a sensible undulation. The travellers continued to feed their fire with the loppings of vines, till this provision being nearly spent, they safely alighted in a corn-field, having traversed about six miles in three quarters of an hour.
Rozier and Proust. About a fortnight afterwards, the same prince was gratified by a more splendid ascent, commanded for his entertainment by the French monarch. A large fire-balloon, carrying the naturalists Rozier and Proust, was launched from the outer court of Versailles. It soared to the height of 12,520 feet, and might appear to float in a vast congregation of extended and towering white clouds. The thermometer stood at 21° of Fahrenheit, and the flakes of snow fell copiously on the voyagers, while it only rained below. Descending again from that chaotic abyss, they were charmed with the lively aspect of a rich and populous district. They alighted at the entrance of the forest of Chantilly, about thirty-six miles from Versailles, after a flight of an hour and five minutes.
We omit the relation of a prosperous ascent performed
VOL. II.
at Rhodés on the 6th of August, by the Abbé Carnus and his companion, with a fire-balloon, of a globular shape, and 57 feet in diameter.—The longest aerial journey yet made was accomplished at Paris, on the 19th of September. The duke de Chartres, afterwards Orleans, and the Duke of noted Egalité, employed Robert to construct for him a Orleans. silk balloon, which should be filled with hydrogen gas. It had 56 feet in height and 36 feet diameter, being composed of a cylinder terminated by two hemispheres; a construction which was rightly supposed to give much additional solidity to the machine. A small bag, on Meusnier's plan, had been introduced within it, and the boat was, besides, furnished with a helm and four oars. This balloon, bearing the duke himself, the two artists, and another companion, and having 500 pounds of ballast, was allowed to rise very slowly, with a buoyancy of only 27 pounds. At the height of 1400 feet, the voyagers perceived, not without uneasiness, thick dark clouds gathering along the horizon, and threatening the approach of a thunder-storm. They heard the distant claps, and experienced something like the agitation of a whirlwind, although they had not felt the slightest concussion in the air from the discharge of cannon. The thermometer suddenly dropped from 77° Fahrenheit to 61°; and the influence of this cold caused the balloon to descend within 200 feet of the tops of the trees near Beauvais. To extricate themselves, they now threw out more than forty pounds of ballast, and rose to an elevation of 6000 feet, where it was found that the confined gas had so obstinately retained its heat, as to be no less than 42° warmer than the external air. The duke became alarmed, and betrayed such impatience to return again to the earth, that he is said to have pierced the lower part of the silk bag in holes with his sword. After narrowly escaping the dangers from wind and thunder, the balloon at last descended in safety near Bethune, having performed a course of 135 miles in the space of five hours.
On the 25th of April in the same year, the celebrated chemist Guyton-Morveau, with the Abbé Bertrand, ascended from Dijon in a balloon, nearly of a globular shape, 29 feet in diameter, composed of the finest varnished tiffany, and filled with hydrogen gas. They did not start till five o'clock in the evening, the barometer being at 29.8 inches, and the thermometer at 57° on Fahrenheit's scale; and, after surmounting some accidents, they rose to an altitude of 10,465 feet, or very nearly two English miles, where the barometer had sunk to 19.8 inches, and the thermometer to 25°. They felt no inconvenience, however, except from the pinching of their ears with cold. They saw an ocean of clouds below them, and in this situation they witnessed, as the day declined, the beautiful phenomenon of a parhelion, or mock sun. The real luminary was only ten degrees above the horizon, when, all at once, another sun appeared to plant itself within six degrees of the former. It consisted of numerous prismatic rings, delicately tinted, on a ground of dazzling whiteness. At half-past six o'clock, after a voyage of an hour and a half, they safely alighted near Magny, about fifteen miles distant from Dijon.
With the same balloon, M. Guyton-Morveau made a second ascent on the 12th of June, accompanied by the President De Virly. It was launched at seven o'clock in the morning, the barometer being then at 29.5 inches, the thermometer at 66°, and Saussure's hygrometer at 81.4°. It swelled very fast, however, owing to the effect of the sun's increasing heat; and the upper valve being at intervals opened, to give vent to excess of the gas, this escaped with a noise like the rushing of water. As the voyagers did not mount to any very great elevation, they enjoyed an agreeable temperature, and could easily, by observing
the situation of the different villages scattered below them, trace out their tortuous route on the surface of the map. By nine o'clock they had reached the height of 6030 feet, the barometer now standing at 24.7 inches, the thermometer at 70°, and the hygrometer at 65. Three quarters of an hour afterwards they descended at the village of Etevaux, only twelve miles from Dijon, having described at least double this distance in the air. The heat had increased so much since the morning, that, notwithstanding the loss of elastic fluid, the balloon seemed yet nearly inflated on touching the ground.
An aerial voyage, most remarkable for its duration and its adventures, was performed on the 18th of June 1786, from Paris, by M. Testu, with a balloon 29 feet in diameter, constructed by himself, of glazed tiffany, furnished with auxiliary wings, and filled, as usual, with hydrogen gas. It had been much injured by wind and rain during the night before its ascension; but having undergone a slight repair, it was finally launched, with its conductor, at four o'clock in the afternoon. The barometer then stood at 29.68 inches, and the thermometer as high as 84°, though the day was cloudy and threatened rain. The balloon had at first been filled only five-sixths, but it gradually swelled as it became drier and warmer, and acquired its utmost distension at the height of 2800 feet. But, to avoid the waste of gas or the rupture of the silk, the navigator endeavoured to descend by the re-action of his wings. Though this force had little efficacy, yet at half-past five o'clock he softly alighted on a corn-field in the plain of Montmorency. Without leaving the car, he began to collect a few stones for ballast; when he was surrounded by the proprietor of the field and a troop of peasants, who insisted on being indemnified for the damage occasioned by his idle and curious visitors. Anxious now to disengage himself, he persuaded them that, his wings being broken, he was wholly at their mercy. They seized the stay of the balloon, which floated at some height, and dragged their prisoner through the air in a sort of triumph towards the village. But M. Testu, finding that the loss of his wings, his cloak, and some other articles, had considerably lightened the machine, suddenly cut the cord, and took an abrupt leave of the clamorous and mortified peasants. He rose to the region of the clouds, where he observed small frozen particles floating in the atmosphere. He heard thunder rolling beneath his feet, and, as the coolness of the evening advanced, the buoyant force diminished, and, at three quarters after six o'clock, he approached the ground near the abbey of Royaumont. There he threw out some ballast, and in the space of twelve minutes rose to a height of 2400 feet, where the thermometer was only 66 degrees. He now heard the blast of a horn, and descried hunters below in full chase. Curious to witness the sport, he pulled the valve, and descended, at eight o'clock, between Etouen and Varville, when, rejecting his oars, he set himself to gather some ballast. While he was thus occupied, the hunters galloped up to him. He mounted a third time, and passed through a dense body of clouds, in which thunder followed lightning in quick succession.
With fresh alacrity and force renew'd,
Springs upward, like a pyramid of fire,
Into the wild expanse, and through the shock
Of fighting elements, on all sides round
Environ'd wins his way.
The thermometer fell to 21°, but afterwards regained its former point of 66°, when the balloon had reached the altitude of 3000 feet. In this region the voyager sailed till half-past nine o'clock, at which time he observed from his "watch-tower in the sky" the final setting of the sun. He was now quickly involved in darkness, and enveloped
in the thickest mass of thunder-clouds. The lightnings flashed on all sides, and the loud claps were incessant. The thermometer, seen by the help of a phosphoric light which he struck, pointed at 21°, and snow and sleet fell copiously around him. In this most tremendous situation the intrepid adventurer remained the space of three hours, the time during which the storm lasted. The balloon was affected by a sort of undulating motion upwards and downwards, owing, he thought, to the electrical action of the clouds. The lightning appeared excessively vivid, but the thunder was sharp and loud, preceded by a sort of crackling noise. A calm at last succeeding, he had the pleasure to see the stars, and embraced this opportunity to take some necessary refreshment. At half-past two o'clock the day broke in; but his ballast being nearly gone, and the balloon again dry and much elevated, he resolved to descend to the earth, and ascertain to what point he had been carried. At a quarter before four o'clock, having already seen the sun rise, he safely alighted near the village of Campremi, about 63 miles from Paris.
At this period, ascents with balloons had been multiplied, not only through France, but all over Europe. They were very seldom, however, directed to any other object than amusement, and had soon degenerated into mere exhibitions for gain. The first balloon seen in England was constructed by an ingenious Italian, the Count Zam-Zambee. It consisted of oiled silk, in a globular shape, about ten feet in diameter, and weighed only eleven pounds. It was entirely gilt, which not only gave it a beautiful appearance, but rendered it less permeable to the gas. On the 25th of November 1783 it was filled about three-fourths, and launched at one o'clock from the artillery ground, and in the presence of a vast concourse of spectators. At half-past three in the afternoon it was taken up at Petworth, in Sussex, about the distance of 48 miles. It was not till the following year, on the 21st of September, that a countryman of his, named Lunardi, first mounted in a balloon at London. He afterwards repeated the experiment in different parts of England, and during the following year in Scotland. This active person took an expeditious but careless method of filling his balloon with gas. He had two large casks, sunk into the ground for their better security, in which he deposited 2000 pounds of the borings of cannon, divided by layers of straw, to present a larger surface. An equal weight of sulphuric acid, or common oil of vitriol, diluted with six times as much water, was poured upon the iron, and the hydrogen gas now formed, without being cooled or washed, was immediately introduced into the balloon. To Lunardi succeeded Blanchard, who possessed just as little science, but had greater pretensions, and some share of dexterity and skill. This adventurer is said to have performed not fewer than thirty-six voyages through the air, and to have acquired a large sum of money by those bold and attractive exhibitions. His most remarkable journey was across the British Channel, in company with Dr Jeffries, an American physician. On the 7th of January 1785, in a clear frosty day, the balloon was launched from the cliff of Dover, and, after a perilous course of two hours and three quarters, it alighted in safety on the edge of the forest of Guennes, not far beyond Calais. By the magistrates of this town were the two aerial travellers treated with the utmost kindness and hospitality; and their wondrous arrival was welcomed as a happy omen, alas! how fallacious, of the lasting harmony to subsist between rival nations, now cemented by the conclusion of the famous Commercial Treaty.
The original smoke balloon of Montgolfier appears to
Aéronautics. have gradually fallen into disrepute, and the more elegant and expensive, but far more powerful construction, which employs varnished silk to contain hydrogen gas, came to be generally preferred. With due precaution and management, the sailing through the atmosphere is perhaps scarcely more dangerous now than the navigating of the ocean. Of some hundred ascents made at different times with balloons, not above two or three cases are recorded to have had a fatal termination. The first was rendered memorable by the shocking death of the accomplished and interesting Rozier, who perished a martyr to his ardent zeal for the promotion of science. Being anxious to return the visit which Blanchard and Jeffries had paid to the French coast, by crossing the channel again and descending in England, he transported his balloon, which was of a globular shape, and forty feet in diameter, to Boulogne; and after various delays, occasioned chiefly by adverse winds, he mounted on the 15th June 1785, with his companion M. Romain. From some vague idea of being better able to regulate the ascent of the balloon, he had most incautiously suspended below it a small smoke one of ten feet diameter; a combination to which may be imputed the disastrous issue. Scarcely a quarter of an hour had elapsed, when the whole apparatus, at the height of above three thousand feet, was observed to be on fire; and its scattered fragments, with the unfortunate voyagers, were precipitated to the ground. They fell near the sea-shore, about four miles from Boulogne, and were instantly killed by the tremendous crash, their bodies being found most dreadfully mangled. The next fatal accident with balloons happened in Italy, several years later, when a Venetian nobleman and his lady, after having performed successfully various ascents, fell from a vast height, and perished on the spot. A few years ago, the younger William Sadler, one of our most skillful aéronauts, who had successfully crossed the Irish channel from Dublin to Anglesey, was killed by collision with a tall chimney, in a descent at Liverpool.
To guard, in some degree, against the risks arising from the occurrence of such accidents, the Parachute was afterwards introduced; being intended to enable the voyager, in case of alarm, to desert his balloon in mid-air, and drop, without sustaining injury, to the ground. The French language, though not very copious, has yet supplied this convenient term, signifying a guard for falling, as it has likewise furnished the words of analogous composition, parapluie, paravent, and parasol, to denote an umbrella, a door-screen, and a shade for the sun. The parachute very much resembles the ordinary umbrella, but has a far greater extent. The umbrella itself, requiring such strength to bear it up against a moderate wind, might naturally have suggested the application of the same principle to break the force of a fall. Nothing was required but to present a surface having dimensions sufficient to experience from the air a resistance equal to the weight of descent, in moving through the fluid with a velocity not exceeding that of the shock which a person can sustain without any danger. Accordingly, in the East, where the umbrella, or rather the parasol, has been from the remotest ages in familiar use, this implement appears to be occasionally employed by vaulters, for enabling them to jump safely from great heights. Father Loubere, in his curious account of Siam, relates that a person, famous in that remote country for his dexterity, was accustomed to divert exceedingly the king and the royal court by the prodigious leaps which he took, having two umbrellas with long slender handles fastened to his girdle. He generally alighted on the ground, but was sometimes carried by the wind against trees or houses, and not unfre-
quently into the river. Not many years since, the umbrella was, at least on one occasion, employed in Europe with similar views, but directed to a very different purpose. In the early part of the campaign of 1793, the French general Bournonville, having been sent by the National Convention, with four more commissioners, to treat with the Prince of Saxe-Cobourg, was, contrary to the faith or courtesy heretofore preserved in the fiercest wars that have raged among civilized nations, detained a prisoner with his companions, and sent to the fortress of Ohmutz, where he suffered a rigorous confinement. In this cruel situation he made a desperate attempt to regain his liberty. Having provided himself with an umbrella, he jumped from a window at the height of forty feet; but being a very large heavy man, this screen proved insufficient to check his precipitate descent. He struck against the opposite wall, fell into the ditch, and broke his leg, and was carried in this condition back again to his dungeon.
Blanchard was the first who constructed parachutes, First used. and annexed them to balloons, for the object of effecting his escape in case of accident. During the excursion which he undertook from Lisle, about the end of August 1785, when this adventurous aéronaut traversed, without halting, a distance not less than 300 miles, he let down a dog from a vast height in the basket of a parachute, and the poor animal, falling gently through the air, reached the ground unhurt. Since that period the practice and management of the parachute have been carried much farther by other aerial travellers, and particularly by M. Garnerin, who has dared repeatedly to descend from the region of the clouds with that very slender machine. This ingenious and spirited Frenchman visited London Garnerin's during the short peace of 1802, and made two fine ascents descent.
with his balloon, in the second of which he threw himself from an amazing elevation with a parachute. This consisted of thirty-two gores of white canvas formed into a hemispherical case of twenty-three feet diameter, at the top of which was a truck or round piece of wood ten inches broad, and having a hole in its centre, admitting short pieces of tape to fasten it to the several gores of the canvas. About four feet and a half below the top, a wooden hoop of eight feet in diameter was attached by a string from each seam; so that when the balloon rose, the parachute hung like a curtain from this hoop. Below it was suspended a cylindrical basket covered with canvas, about four feet high, and two and a quarter wide. In this basket the aéronaut, dressed in a close jacket and a pair of trousers, placed himself, and rose majestically from an inclosure near North Audley Street at six o'clock in the evening of the 2d of September. After hovering seven or eight minutes in the upper region of the atmosphere, he meditated a descent in his parachute. Well might he be supposed to linger there in dread suspense, and to
..... look a while
Pondering his voyage: for no narrow frith
He had to cross.....
He views the breadth, and, without longer pause,
Downright into the world's first region throws
His flight precipitant, and winds with ease,
Through the pure marble air, his oblique way.
He cut the cord by which his parachute was attached to the net of the balloon; it instantly expanded, and for some seconds it descended with an accelerating velocity, till it became tossed extremely, and took such wide oscillations that the basket or car was at times thrown almost into a horizontal position. Borne along likewise by the influence of the wind, the parachute passed over Mary-lebone and Somers-town, and almost grazed the houses of St. Pancras. At last it fortunately struck the ground in a
Aéronautics. neighbouring field; but so violent was the shock as to throw poor Garnerin on his face, by which accident he received some cuts, and bled considerably. He seemed to be much agitated, and trembled exceedingly at the moment he was released from the car. One of the stays of the parachute had chanced to give way; which untoward circumstance deranged the apparatus, disturbed its proper balance, and threatened the adventurer, during the whole of his descent, with immediate destruction. The feeling of such extreme peril was too much for human nature to bear.
Theory of the parachute. From the principles before explained, we may easily determine the descent of a parachute. When, with its attached load, it is abandoned in the air, it must, from the continued action of gravity, proceed at first with an accelerated motion, till its increasing velocity comes to oppose a resistance equal to the force of attraction, or to the combined weight of the whole apparatus. After this counterpoise has taken place, there existing no longer any cause of acceleration, the parachute should descend uniformly with its acquired rapidity. This perfect equilibrium will not, however, be attained at once. The accumulation of swiftness produced by the unceasing operation of gravity, is not immediately restrained by the corresponding increased resistance of the atmosphere. The motion of a parachute must hence, for some short time, be subject to a sort of interior oscillation, alternately accelerating and retarding. It first shoots beyond the terminal velocity, and then, suffering greater resistance, it relaxes, and contracts within the just limits. This unequal and undulating progress which a parachute exhibits subsequently to the commencement of its fall, is calculated to excite disproportionate alarms of insecurity and danger.
Rate of its descent. The terminal velocity of a parachute, or the uniform velocity to which its motion tends, would, according to theory, be equal, if its surface were flat, to the velocity that a heavy body must acquire in falling through the altitude of a column of air incumbent on that surface, and having, under the usual circumstances, the same weight as the whole apparatus. But we have already seen, that a cylinder of air, one foot in diameter and height, weighs only, in ordinary cases, the seventeenth part of a pound avoirdupois. Wherefore, if the square of the diameter of a parachute be divided by 17, the quotient will give the number of pounds equivalent to the weight of an atmospheric column of one foot; and the weight of the apparatus being again divided by this quotient, the result will express the entire altitude of an equiperderant column. Of this altitude, the square root multiplied by 8 will denote the final velocity, or that with which the parachute must strike the ground. Suppose, for example, that the diameter of the parachute were 25 feet: then ; and this, divided by 17, gives . Consequently, if the parachute with its load weighed only pounds, the shock received at the surface of the earth would be precisely the same as that which is felt in dropping from an elevation of one foot. Had the weight of the apparatus, therefore, been four times greater, or pounds, the shock sustained would be the same as that from a fall of four feet; which is near the limit, perhaps, of what a person can bear without suffering injury from the violence of concussion. The velocity of descent, on this latter supposition, would be , or sixteen feet each second.
Correct formula. But the actual resistance of the air is rather greater than what theory would give; and it is besides augmented by the concavity of the opposing surface, which occasions an accumulation of the fluid. Let denote the diameter of a parachute, and the total weight of the apparatus abandoned to its gravity in the atmosphere; if we take Dr
Hutton's valuable experiments for the basis of the calculation, the terminal velocity of descent may be expressed in round numbers, by , in feet each second, and consequently the length of fall which would occasion the same shock, is , or very nearly . Thus, if the parachute had thirty feet in diameter, and weighed, together with its appended load, 225 pounds; then feet, or the velocity with which it would strike the ground; and feet, being the height from which a person dropping freely would receive the same shock.
Since the resistance which air opposes to the passage of Celerity in a body is diminished by rarefaction, it is evident, that the higher parachute disengaged from a balloon, in the more elevated regions of the atmosphere, will at first acquire a greater velocity than it can afterwards maintain as it approaches the ground. Resuming the notation employed before, the ratio of the density of the air at the surface, and at any given height, being expressed by ; then the velocity of counterpoise at that elevation would be , or it would be equal to what is accumulated in falling freely a height of feet. It is the final velocity, however, that must be chiefly considered in parachutes, being what determines the shock sustained in alighting. The violence of the rushing through the air will seldom be attended with any serious inconvenience. If we suppose the mean velocity with which a parachute descends to be twelve feet each second, this will correspond to the rate of a mile in minutes; not more than that of a very gentle trot. We are not told from what height Garnerin dropped; but if he took four minutes in his descent, it was probably about half a mile.
The practice of aeronautics has not realized those expectations of benefit to mankind which sanguine projectors were at first disposed to entertain. It was soon found, that a balloon, launched into the atmosphere, is abandoned, without guidance or command, to the mercy of the winds. To undertake to direct or impel the floating machine by any exertion of human strength, was evidently a chimerical attempt. All the influence which the aeronaut really possesses consists in a very limited power of raising or depressing it, according to circumstances. He cannot hope to shape his course, unless by skilfully adapting his elevation to catch the prevailing currents.
Almost the only purpose to which balloons have hitherto been applied with success, had for its object that of used in military reconnaissance. In the early part of the French revolutionary war, when ingenuity and science were so eagerly called into active service, a balloon, prepared under the direction of the Aerostatic Institute in the Polytechnic School, and intrusted to the command of two or three experienced officers, was distributed to each of the republican armies. The decisive victory which General Jourdan gained, in June 1794, over the Austrian forces in the plains of Fleurus, has been ascribed principally to the accurate information of the enemy's movements before and during the battle, communicated by telegraphical signals from a balloon which was sent up to a moderate height in the air. The aeronauts, at the head of whom was the cele-
Aéronautics. brated Guyton-Morveau, mounted twice in the course of that day, and continued, about four hours each time, hovering in the rear of the army at an altitude of 1300 feet. In the second ascent, the enterprise being discovered by the enemy, a battery was opened against them; but they soon gained an elevation above the reach of the cannon. Another balloon, constructed by the same skilful artist, M. Conté, was attached to the army sent on the memorable expedition to Egypt. What service it rendered the daring invader in the wide plains and sandy deserts of Africa, we are not informed; but, after the capitulation of Cairo, it was brought back, with the remains of the army, to France, and employed in the sequel, as we shall find, more innocently in philosophical research. These balloons, being calculated for duration, were of a more solid and perfect construction than usual. Originally they were filled with hydrogen gas, obtained from the decomposition of water on a large scale. For this purpose, six iron cylinders had been fixed by masonry in a simple kind of furnace, each of their ends projecting, and covered with an iron lid. Two sets of metal tubes were also inserted, the one for conveying hot water, and the other for carrying off the gas which was formed. The cylinders being charged with iron-turnings, and brought to a red heat, the humidity was instantly converted into steam, and decomposed, the oxygen uniting with the iron, while the hydrogen gas was discharged, and made to deposit any carbonic gas that might adhere to it, by passing through a reservoir filled with caustic lye before it entered the balloon. By this method there was procured, at a very moderate expense, and in the space of about four hours, a quantity of hydrogen gas sufficient to inflate a balloon of thirty feet in diameter.
The ascents with balloons should appear to furnish the readiest means of ascertaining important facts in meteorology and atmospheric electricity, departments of science which are still unfortunately in their infancy. Some aéronauts have asserted that the magnetic needle ceased to traverse at very great elevations in the atmosphere; a statement which received some countenance from the observations made by Saussure on the lofty summit of the Col du Géant, where that celebrated naturalist thought he had found the magnetic virtue to be diminished one fifth part. It has been pretended by others, that the air of the higher regions is not of the same composition as at the surface of the earth, and is, independently altogether of its rarity, less fitted for the purpose of respiration. To determine these, and other relative points, was, therefore, an object interesting to the progress of physical science. A few years since, two young and ardent French philosophers, MM. Biot and Gay-Lussac, proposed to undertake an aerial ascent, in order to examine the magnetic force at great elevations, and to explore the constitution of the higher atmosphere and its electrical properties. For such a philosophical enterprise they were eminently qualified, having been educated together at the Polytechnic School, and both of them deeply versed in mathematics; the former indulging in a wide range of study, and the latter concentrating his efforts more on chemistry and its application to the arts. Their offer to government was seconded by Berthollet and Laplace, and the celebrated chemist Chaptal, then minister of the interior, gave it his patronage and warm support. The balloon which had once visited Egypt was delivered to the custody of Biot and Gay-Lussac; and the same artist who constructed it was, at the public expense, ordered to refit and prepare it under their direction. Besides the usual provision of barometers, thermometers, hygrometers, and electrometers, they had two compasses, and a dipping-needle, with another fine needle,
carefully magnetized, and suspended by a very delicate silk thread, for ascertaining by its vibrations the force of magnetic attraction. To examine the electricity of the different strata of the atmosphere, they carried several metallic wires, from sixty to three hundred feet in length, and a small electrophorus feebly charged. For galvanic experiments they had procured a few discs of zinc and copper, with some frogs; to which they added insects and birds. It was also intended to bring down a portion of air from the higher regions, to be subjected to a chemical analysis; and for this purpose a flask, carefully exhausted, and fitted with a stop-cock, had been prepared.
The balloon was placed in the garden of the Conservatoire des Arts, or Repository of Models, formerly the Convent of St Martin; and no pains were spared by Conté in providing whatever might contribute to the greater safety and convenience of the voyagers. Every thing being now ready for their ascent, these adventurous philosophers, in the presence of a few friends, embarked in the car at ten o'clock in the morning of the 23d of August 1804. The barometer was then at 30.13 inches, the thermometer at 61.7° on Fahrenheit's scale, and Saussure's hygrometer pointed at 80.8°, or very near the limit of absolute humidity. They rose with a slow and imposing motion. Their feelings were at first absorbed in the novelty and magnificence of the spectacle which opened before them; and their ears were saluted with the buzz of distant gratulations, sent up from the admiring spectators. In a few minutes they entered the region of the clouds, which seemed like a thin fog, and gave them a slight sensation of humidity. The balloon had become quite inflated, and they were obliged to let part of the gas escape, by opening the upper valve; at the same time, they threw out some ballast, to gain a greater elevation. They now shot through the range of clouds, and reached an altitude of about 6500 English feet. These clouds, viewed from above, had the ordinary whitish appearance; they all occupied the same height, only their upper surface seemed marked with gentle swells and undulations, exactly resembling the aspect of a wide plain covered with snow.
MM. Biot and Gay-Lussac now began their experimental operations. The magnetic needle was attracted, as usual, by iron; but they found it impossible at this time to determine with accuracy its rate of oscillation, owing to a slow rotatory motion with which the balloon was affected. In the meanwhile, therefore, they made other observations. A Voltaic pile, consisting of twenty pairs of plates, exhibited all its ordinary effects,—gave the pungent taste, excited the nervous commotion, and occasioned the decomposition of water. By rejecting some more ballast, they had attained the altitude of 8940 feet, but afterwards settled to that of 8600 feet. At this great elevation, the animals which they carried with them appeared to suffer from the rarity of the air. They let off a violet bee, which flew away very swiftly, making a humming noise. The thermometer had fallen to 56.4° by Fahrenheit, yet they felt no cold, and were, on the contrary, scorched by the sun's rays, and obliged to lay aside their gloves. Both of them had their pulses much accelerated: that of Biot, which generally beat seventy-nine times in a minute, was raised to one hundred and eleven; while the pulse of his friend Gay-Lussac, a man of a less robust frame, was heightened from sixty to eighty beats in the minute. Notwithstanding their quickened pulsation, however, they experienced no sort of uneasiness, nor any difficulty in breathing.
What perplexed them the most was the difficulty of observing the oscillations of a delicately suspended magnetic needle. But they soon remarked, on looking atten-
tively down upon the surface of the conglomerated clouds, that the balloon slowly revolved, first in one direction, and then returned the contrary way. Between these opposite motions there intervened short pauses of rest, which it was necessary for them to seize. Watching, therefore, the moments of quiescence, they set the needle to vibrate, but were unable to count more than five, or very rarely ten oscillations. A number of trials, made between the altitudes of 9500 and 13,000 feet, gave 7" for the mean length of an oscillation, while at the surface of the earth it required 7" to perform each oscillation. A difference so very minute as the hundred and fortieth part could be imputed only to the imperfection of the experiment; and it was hence fairly concluded, that the force of magnetic attraction had in no degree diminished at the greatest elevation which they could reach. The direction of this force, too, seemed, from concurring circumstances, to have continued the same; though they could not depend on observations made in their vacillating car with so delicate an instrument as the dipping needle.
At the altitude of 11,000 feet they liberated a green linnet, which flew away directly; but, soon feeling itself abandoned in the midst of an unknown ocean, it returned and settled on the stays of the balloon. Then mustering fresh courage, it took a second flight, and dashed downwards to the earth, describing a tortuous yet almost perpendicular track. A pigeon which they let off under similar circumstances afforded a more curious spectacle. Placed on the edge of the car, it rested a while, measuring as it were the breadth of that unexplored sea which it designed to traverse: now launching into the abyss, it fluttered irregularly, and seemed at first to try its wings in the thin element; till, after a few strokes, it gained more confidence, and, whirling in large circles or spirals, like the birds of prey, it precipitated itself towards the mass of extended clouds, where it was lost from sight.
It was difficult, in those lofty and rather humid regions, to make electrical observations; and the attention of the scientific navigators was besides occupied chiefly by their magnetical experiments. However, they let down from the car an insulated metallic wire of about 250 feet in length, and ascertained, by means of the electrophorus, that the upper end indicated resinous or negative electricity. This experiment was several times repeated; and it seemed to corroborate fully the previous observations of Saussure and Volta relative to the increase of electricity met with in ascending the atmosphere.
The diminution of temperature in the higher regions was found to be less than what is generally experienced at the same altitude on mountains. Thus, at the elevation of 12,800 feet, the thermometer was at 51° by Fahrenheit, while it stood as low as 63° at the observatory; being only a decrement of one degree for each 1000 feet of ascent. This fact corresponds with the observations made by former aéronauts, and must have been produced, we conceive, by the operation of two distinct causes. First, the rays from the sun, not being enriched by passing through the denser portion of the atmosphere, would act with greater energy on the balloon and its car, and consequently affect the thermometer placed in their vicinity. Next, the warm current of air, which during the day rises constantly from the heated surface of the ground, must augment the temperature of any body which is exposed to its influence. During the night, on the contrary, the upper strata of the atmosphere would be found colder, we presume, than the general standard, owing to the copious descent of chill portions of air from the high-
est regions. The hygrometer, or rather hygroscope, of Saussure, ad-
vanced regularly towards dryness, in proportion to the altitude which they attained. At the elevation of 13,000 feet it had changed from 80.8° to 30°. But still the conclusion, that the air of the higher strata is drier than that of the lower, we are inclined to consider as fallacious. In fact, the indications of the hygroscope depend on the relative attraction for humidity possessed by the substance employed, and the medium in which it is immersed. But air has its disposition to retain moisture always augmented by rarefaction, and consequently such alteration alone must materially affect the hygroscope. The only accurate instrument for ascertaining the condition of air with respect to dryness is founded on a property of evaporation. But we shall afterwards have occasion to discuss this subject at due length.
The ballast now being almost quite expended, it was Their resolved to descend. The aéronauts therefore pulled the descent upper valve, and allowed part of the hydrogen gas to escape. They dropped gradually, and when they came to the height of 4000 feet, they met the stratum of clouds, extending horizontally, but with a surface heaved into gentle swells. When they reached the ground, no people were near them to stop the balloon, which dragged the car to some distance along the fields. From this awkward and even dangerous situation they could not extricate themselves without discharging the whole of their gas, and therefore giving up the plan of sending M. Gay-Lussac alone to explore the highest regions. It has been reported that his companion M. Biot, though a man of activity and not deficient in personal courage, was so much overpowered by the alarms of their descent, as to lose for the time the entire possession of himself. The place where they alighted, at half-past one o'clock, after three hours and a half spent in the midst of the atmosphere, was near the village of Meriville, in the department of the Loiret, and about fifty miles from Paris.
It was the desire of several philosophers at Paris, that M. Gay-Lussac should mount a second time, and repeat the different observations at the greatest elevation he could attain. Experience had instructed him to reduce his apparatus, and to adapt it better to the actual circumstances. As he could only count the vibrations of the magnetic needle during the very short intervals which occurred between the contrary rotations of the balloon, he preferred one of not more than six inches in length, which therefore oscillated quicker. The dipping needle was magnetized and adjusted by the ingenious M. Coulomb. To protect the thermometer from the direct action of the sun, it was inclosed within two concentric cylinders of pasteboard covered with gilt paper. The hygrometers, constructed on Richer's mode, with four hairs, were sheltered nearly in the same way. The two glass flasks intended to bring down air from the highest regions of the atmosphere had been exhausted till the mercurial gage stood at the 25th part of an inch, and their stop-cocks were so perfectly fitted, that, after the lapse of eight days, they still preserved the vacuum. These articles, with two barometers, were the principal instruments which M. Gay-Lussac took with him. The skill and intelligence of the artist had been exerted in further precautions for the safety of the balloon.
At forty minutes after nine o'clock on the morning of Gay-Lus- the 15th of September, the scientific voyager ascended, as before, from the garden of the Repository of Models. The barometer then stood at 30.66 English inches, the thermometer at 82° by Fahrenheit, and the hygrometer at 57°. The sky was unclouded, but misty. Scarcely had the observer reached the height of 3000 feet, when he observed spread below him, over the whole extent of the
Aéronautics. atmosphere, a thin vapour, which rendered the distant objects very indistinct. Having gained an altitude of 9950 feet, he set his needle to vibrate, and found it to perform twenty oscillations in 83", though it had taken 84.33" to make the same number at the surface of the earth. At the height of 12,680 feet he discovered the variation of the compass to be precisely the same as below; but with all the pains he could take, he was unable to determine with sufficient certainty the dip of the needle. M. Gay-Lussac continued to prosecute his other experiments with the same diligence, and with greater success. At the altitude of 14,480 feet he found that a key, held in the magnetic direction, repelled with its lower end, and attracted with its upper end, the north pole of the needle of a small compass. This observation was repeated, and with equal success, at the vast height of 20,150 feet; a clear proof that the magnetism of the earth exerts its influence at remote distances. He made not fewer than fifteen trials at different altitudes, with the oscillations of his finely suspended needle. It was generally allowed to vibrate twenty or thirty times. The mean result gives 4.22" for each oscillation, while it was 4.216" at the surface of the earth: an apparent difference so extremely small, as to be fairly neglected.
Successive decrements of temperature. During the whole of his gradual ascent, he noticed, at short intervals, the state of the barometer, the thermometer, and the hygrometer. Of these observations, amounting in all to twenty-one, he has given a tabular view. We regret, however, that he has neglected to mark the times at which they were made, since the results appear to have been very considerably modified by the progress of the day. It would likewise have been desirable to have compared them with a register noted every half hour at the Observatory. From the surface of the earth to the height of 12,125 feet, the temperature of the atmosphere decreased regularly from 82° to 47.3° by Fahrenheit's scale. But afterwards it increased again, and reached to 53.6°, at the altitude of 14,000 feet; evidently owing to the influence of the warm currents of air which, as the day advanced, rose continually from the heated ground. From that point the temperature diminished, with only slight deviations from a perfect regularity. At the height of 18,636 feet the thermometer subsided to 32.9°, on the verge of congelation; but it sunk to 14.9° at the enormous altitude of 22,912 feet above Paris, or 23,040 feet above the level of the sea, the utmost limit of the balloon's ascent.
Comparison of these observations. From these observations no conclusive inference, we think, can be drawn respecting the mean gradation of cold which is maintained in the higher regions of the atmosphere: for, as we have already remarked, the several strata are during the day kept considerably above their permanent temperature by the hot currents raised from the surface through the action of the sun's rays. If we adopt the formula given by Professor Leslie at the end of his Elements of Geometry, which was the result of some accurate and combined researches, the diminution of temperature corresponding to the first part of the ascent, or 12,125 feet, ought to be forty degrees of Fahrenheit. It was actually 34.7°, and would no doubt have approached to 40°, if the progressive heating of the surface, during the interval of time, were taken into the account. In the next portion of the voyage, from the altitude of 14,000 to that of 18,636 feet, or the breadth of 4636 feet, the decrement of temperature according to the formula should only have been 16.1°, instead of 20.7°, which was really marked; a proof that the diurnal heat from below had not yet produced its full effect at such a great height. In the last portion of the balloon's ascent, from 18,636 feet to
22,912, a range of 4276 feet, the decrease of heat ought to be 15.1°, and it was actually 18°; owing most probably to the same cause, or the feeble influence which warm currents of air from the surface exert at those vast elevations. Taking the entire range of the ascent, or 22,912 feet, the diminution of temperature according to the same formula would be for the gradation of temperature in ascending the atmosphere 85.4°. The decrease actually observed would be 67.1°, which might be raised to 80°, if we admit the very probable supposition, that the surface of the earth had become heated from 82° to 94.9° during the interval between ten o'clock in the morning and near three in the afternoon, when the balloon floated at its greatest elevation.
After making the fair allowances, therefore, on account of the operation of deranging causes, the results obtained by M. Gay-Lussac, for the gradation of temperature in the atmosphere, appear, on the whole, to agree very nearly with those derived from the formula which theory, guided by delicate experiments, had before assigned. This gradation is evidently not uniform, as some philosophers have assumed; but proceeds with augmented rapidity in the more elevated regions. The same conclusion results from a careful inspection of the facts which have been stated by other observers.
The hygrometers, during the ascent of the balloon, held indications of a progress not quite so regular, but tending obviously towards dryness. At the height of 9950 feet they had changed from 57.5° to 62°; from which point they continued afterwards to decline, till they came to mark 27.5°, at the altitude of 15,190 feet. From this inferior limit the hygrometers advanced again, yet with some fluctuations, to 35.1°, which they indicated at the height of 18,460 feet. Above this altitude the variation was slight, though rather inclining to humidity. There can exist no doubt, however, that, allowing for the influence of the prevailing cold, the higher strata of the atmosphere must be generally drier than the lower, or capable of retaining, at the same temperature, a larger share of moisture.
At the altitude of 21,460 feet M. Gay-Lussac opened one of his exhausted flasks; and, at that of 21,790 feet, the other. The air rushed into them through the narrow aperture, with a whistling noise. He still rose a little higher, but, at eleven minutes past three o'clock, he had attained the utmost limit of his ascent, and was then 22,912 feet above Paris, or 23,040 feet, being more than four miles and a quarter, above the level of the sea. The air was now more than twice as thin as ordinary, the barometer having sunk to 12.95 inches. From that stupendous altitude, sixteen hundred feet above the summit of the Andes, more elevated than the loftiest pinnacle of our globe, and far above the heights to which any mortal had ever soared, the aerial navigator might have indulged the feelings of triumphant enthusiasm. But the philosopher, in perfect security, was more intent on calmly pursuing his observations. During his former ascent, he saw the fleecy clouds spread out below him, while the canopy of heaven seemed of the deepest azure, more intense than Prussian blue. This time, however, he perceived no clouds gathered near the surface, but remarked a range of them stretching, at a very considerable height, over his head: the atmosphere, too, wanted transparency, and had a dull, misty appearance. The different aspect of the sky was probably owing to the direction of the wind, which blew from the north-north-west in his first voyage, but in his second from the south-east.
While occupied with experiments at this enormous elevation, he began, though warmly clad, to suffer from ex-
Aéronautics. cessive cold, and his hands, by continual exposure, grew benumbed. He felt likewise a difficulty in breathing, and his pulse and respiration were much quickened. His throat became so parched from inhaling the dry attenuated air, that he could hardly swallow a morsel of bread; but he experienced no other direct inconvenience from his situation. He had indeed been affected, through the whole of the day, with a slight headache, brought on by the preceding fatigues and want of sleep; but though it continued without abatement, it was not increased by his ascent.
His descent. The balloon was now completely distended, and not more than 33 pounds of ballast remained: it began to drop, and M. Gay-Lussac, therefore, only sought to regulate its descent. It subsided very gently, at the rate of about a mile in eight minutes; and after the lapse of thirty-four minutes, or at three quarters after three o'clock, the anchor touched the ground, and instantly secured the car. The voyager alighted with great ease near the hamlet of St Gourgon, about sixteen miles north-west from Rouen. The inhabitants flocked around him, offering him assistance, and eager to gratify their curiosity.
His analysis of the air brought down. As soon as he reached Paris, he hastened to the laboratory of the Polytechnic School, with his flasks, containing air of the higher regions, and proceeded to analyze it in the presence of Thenard and Gresset. Opened under water, the liquid rushed into them, and apparently half filled their capacity. The transported air was found, by a very delicate analysis, to contain exactly the same proportions as that collected near the surface of the earth, every 1000 parts holding 215 of oxygen. From concurring observations, therefore, we may conclude that the atmosphere is essentially the same in all situations.
Remarks on these last ascents. The ascents performed by MM. Biot and Gay-Lussac are memorable, for being the first ever undertaken solely for objects of science. It is impossible not to admire the intrepid coolness with which they conducted those experiments, operating, while they floated in the highest regions of the atmosphere, with the same composure and precision as if they had been quietly seated in their cabinets at Paris. Their observations on the force of terrestrial magnetism show most satisfactorily its deep source and wide extension. The identity of the constitution of the atmosphere to a vast altitude was likewise ascertained. The facts noted by Gay-Lussac, relative to the state of the thermometer at different heights, appear generally to confirm the law which theory assigns for the gradation of temperature in the atmosphere; but many interesting points were left untouched by this philosopher. We are sorry that he had not carried with him the cyano-meter, which enabled Saussure to determine the colour of the sky on the summits of the Swiss mountains. Still more we regret that he was not provided with an hygrometer and a photometer, of Leslie's construction. These delicate instruments could not have failed, in his hands, to furnish important data for discovering the relative dryness and transparency of the different strata of air. It would have been extremely interesting, at such a tremendous height, to have measured with accuracy the feeble light reflected from the azure canopy of heaven, and the intense force of the sun's direct rays, and hence to have determined what portion of them is absorbed in their passage through the lower and denser atmosphere.
Since that time numerous ascents have been performed in different countries, generally by adventurers guided by no philosophical views, nor leading to any valuable results. It would therefore be superfluous to recount such repeated attempts.
Various projects with balloons. Balloons have at different times been thought capable of useful application. It has been even proposed to employ
their power of ascension as a mechanical force. This might be rendered sufficient, it was believed, to raise water from mines, or to transport obelisks, and place them on great elevations. We can easily imagine situations where a balloon could be used with advantage; such as to raise, without any scaffolding, a cross or a vane to the top of a high spire. But the power would then be purchased at a very disproportionate expense. It would require 4½ pounds of iron, or 6 of zinc, with equal quantities of sulphuric acid, to yield hydrogen gas sufficient to raise up the weight of one pound.
The proposal of employing balloons in the defence and attack of fortified places appears truly chimerical. They have rendered important service, however, in reconnoitring the face of a country, and communicating military signals; and it is rather surprising that a system, which promised such obvious benefits, has not been carried much farther.
But to a skilful and judicious application of balloons, we may yet look for a most essential improvement of the in-fant science of meteorology. Confined to the surface of this globe, we have no direct intimation of what passes in the lofty regions of the atmosphere. All the changes of weather, which appear so capricious and perplexing, proceed, no doubt, from the combination of a very few simple causes. Were the philosopher to penetrate beyond the seat of the clouds, examine the circumstances of their formation, and mark the prevailing currents, he would probably remove in part the veil that conceals those mighty operations. It would be quite practicable, we conceive, to reach an elevation of seven miles, where the air would be four times more attenuated than ordinary. A silk balloon, of forty feet diameter, if properly constructed, might be sufficient for that enormous ascent, since its weight would only be 80 pounds, while its buoyant force, though not more than a quarter filled with hydrogen gas, would amount to 533¾, leaving 453¾ pounds for the passenger and the ballast. The balloon could be safely charged, indeed, to the third part of its capacity, on account of the contraction which the gas would afterwards suffer from the intense cold of the upper regions; and this gives it an additional buoyancy of 177¾ pounds. The voyager would not, we presume, suffer any serious inconvenience from breathing the very thin air. The animal frame adapts itself with wonderful facility to external circumstances. Perhaps the quickened pulse and short respiration, which some travellers have experienced on the summits of lofty mountains, should be attributed chiefly to the suddenness of their transition, and the severity of the cold. The people of Quito live comfortably 9560 feet above the level of the sea; and the shepherds of the hamlet of Antisana, the highest inhabited spot in the known world, who breathe, at an elevation of 13,500 feet, air that has only three-fifths of the usual density, are nowise deficient in health or vigour. But the intenseness of the cold is probably what the resolute observer would have most to dread, at the height of seven miles. This decrease of temperature, perhaps equal to 148 degrees, might extend below the point at which mercury freezes. Yet several circumstances tend to mitigate such extreme cold, and proper clothing might enable an experimenter for a short time to resist its effects.
Much could be done, however, without risk or material expense. Balloons from fifteen to thirty feet in diameter, and carrying register thermometers and barometers, might be capable of ascending alone to altitudes between eight and twelve miles. Dispatched from the centres of the great continents, they would not only determine the extreme gradation of cold, but indicate by their flight the
Aerophylacea
Æs.
direction of the regular and periodic winds which doubtless obtain in the highest regions of the atmosphere. But we will not enlarge. In some happier times, such experiments may be performed with the zealous concurrence of different governments;—when nations shall at last become satisfied with cultivating the arts of peace; instead of wasting their energies in sanguinary, destructive, and fruitless wars.
In Plate II. there is a view of the principal balloons. The figure in the centre represents the shape of the gores
AEROPHYLACEA, a term used by naturalists for caverns or reservoirs of air, supposed to exist in the bowels of the earth.
AEROPHYTES, a designation sometimes applied to parasite plants.
AERSCHOT, a once fortified city of Belgium, on the river Demer, 7 miles from Louvain, and 20 from Antwerp, containing 4053 inhabitants.
ERTSEN, PETER, a Dutch historical painter of great merit, both for drawing and colouring. His master-pieces are an altar-piece at Delft, representing the Nativity and the Wise Men's Offering, and one at Amsterdam of the Death of the Virgin. He died in 1575, aged 56.
ÆRUGINOUS, an epithet given to such things as resemble or partake of the nature of the rust of copper.
ÆRUGO, a Latin term which properly signifies the rust of copper, whether natural or artificial. The former is found about copper mines, and the latter, called verdigris, is made by corroding copper plates with acids.
ÆRUSCATORES, in Antiquity, a kind of strolling beggars, not unlike gypsies, who drew money from the credulous by fortune-telling, &c. It was also a denomination given to gipping exactors, or collectors of the revenue. The Galli, or priests of Cybele, were called æruscatores magnæ matris; and πυρπαγῶντες, from their begging in the streets; to which end they had little bells to draw people's attention, similar to some orders of mendicants abroad.
ÆS, commonly translated brass: but the æs of the Romans was a bronze, or alloy of copper and tin; and the cutting instruments of the ancient Greeks and Egyptians were also of bronze. The Romans borrowed their arms, as well as their money, from the Etruscans. Analysis of the bronzes of these nations shew that they contain from 8 to 12 per cent. of tin, which gave them hardness and the capability of receiving a good edge.
ÆS CIRCUMFORANEUM, money borrowed from the usurers around the Roman Forum. (Cic. ad. Attic. ii.)
ÆS EQUESTRE, ÆS HORDEARIUM, ÆS MILITARE, ancient terms for the pay of Roman soldiers, previous to the introduction of the regular stipendium, and furnished, it would appear, not from the public treasury, but by certain private persons as decreed by the state. The first, which amounted to 10,000 asses, was the purchase-money of the horse of an Eques; the second, amounting to 2000 asses, was the pay of an Eques, and was furnished by maidens, widows, and orphans, if possessed of a certain amount of property, in consideration that they enjoyed protection, and were not included in the census; and it seems probable that they were also charged with the payment of the Æs Equestre: the third, which Niebuhr reckons at 1000 asses a-year (the year then containing but 10 months), was the pay of a foot-soldier, and probably was provided by the tribuni ararii, who would appear to have been private persons who received that title as collectors of the tributum for paying the army.—See Smith's Dict. of Greek and Roman Antiquities, 2d. edition.
VOL. II.
for forming the cloth into a globular shape. Æ, the length of the gore, is equal to the half of the circumference of the globe; BC, the breadth, is the same proportional part of the circumference as the number of gores which it requires to form the sphere. The figures between CB and A denote the breadths of the half-gore, at equal distances from the centre; the breadth BD at the centre being taken equal to 1, and the others in decimals. In this manner it is easy to construct an exact pattern of the gores, all which, being united, will form a true sphere.
ÆS UXORIUM, in Antiquity, a sum paid by bachelors, as a penalty for living single to old age. This tax for not marrying seems to have been first imposed in the year of Rome 350, under the censorship of M. Furius Camillus and M. Posthumus. At the census, or review of the people, each person was asked, Et tu ex animi sententia uxorem habes liberorum querendorum causa? He who had no wife was hereupon fined after a certain rate, called æs uxorium.
Per Æs et libram was a formula in the Roman law, whereby purchases and sales were ratified. Originally the phrase seems to have been only used in speaking of things sold by weight, or by the scales; but it afterwards was used on other occasions. Hence even in adoptions, as there was a kind of imaginary purchase, the formula thereof expressed, that the person adopted was bought per æs et libram.
ÆSCHINES, an Athenian, a Socratic philosopher, the son of Charinus, a sausage-maker. He was continually with Socrates; which occasioned this philosopher to say, that the sausage-maker's son was the only person who knew how to pay a due regard to him. It is said that poverty obliged him to go to Sicily to Dionysius the tyrant; and that he met with great contempt from Plato, but was extremely well received by Aristippus, to whom he showed some of his dialogues, and received from him a handsome reward. He would not venture to profess philosophy at Athens, Plato and Aristippus being in such high esteem; but he opened a school, in which he taught philosophy to maintain himself. He afterwards wrote orations for the forum. Phrynichus, in Photius, ranks him amongst the best orators, and mentions his orations as the standard of the pure Attic style. Hermogenes has also spoken very highly of him. He wrote, besides, several Dialogues: 1. Concerning virtue, whether it can be taught. 2. Eryxias, or Erasistratus; concerning riches, whether they are good. 3. Axiachus; concerning death, whether it is to be feared,—but those extant on the several subjects, are not genuine remains. M. le Clerc has given a Latin translation of them, with notes and several dissertations, entitled Silva Philologicæ.
ÆSCHINES, a celebrated Grecian orator, was born in Attica 389 years before the Christian era. According to his own account, he was of distinguished birth; according to that of Demosthenes, he was the son of a courtesan, and a humble performer in a company of comedians. But whatever was the true history of his birth and early life, his talents, which were considerable, procured him great applause, and enabled him to be a formidable rival to Demosthenes himself. The two orators, inspired probably with mutual jealousy and animosity, became at last the strenuous leaders of opposing parties. Æschines was accused by Demosthenes of having received money as a bribe, when he was employed on an embassy to Philip of Macedon. He indirectly retaliated the charge by bringing an accusation against Ctesiphon, the friend of Demosthenes, for having moved a decree, contrary to the laws, to confer on Demosthenes a golden crown, as a mark of public approbation. A numerous as-
Æschylus, a semblance of judges and citizens met to hear and decide the question. Each orator employed all his powers of eloquence; but Demosthenes, with superior talents, and with justice on his side, was victorious; and Æschines was sent into exile. The resentment of Demosthenes was now softened into generous kindness; for when Æschines was going into banishment, he requested him to accept of a sum of money; which made him exclaim, "How do I regret leaving a country where I have found an enemy so generous, that I must despair of ever meeting with a friend who shall be like him!"
Æschines opened a school of eloquence at Rhodes, which was the place of his exile; and he commenced his lectures by reading to his audience the two orations which had been the cause of his banishment. His own oration received great praise, but that of Demosthenes was heard with boundless applause. In so trying a moment, when vanity must be supposed to have been deeply wounded, with a noble generosity of sentiment, he said, "What would you have thought if you had heard him thunder out the words himself?"—Æschines afterwards removed to Samos, where he died in the 75th year of his age. Three only of his orations are extant. His eloquence is not without energy, but it is diffuse and ornamented, and more calculated to please than to move the passions.
ÆSCHYLUS, the father of the Greek tragic drama, was born in the year 525 B.C., in the Attic demos of Eleusis. The period of his youth and manhood coincides, therefore, with that great uprising of the national spirit of the Greeks, caused by the successive attempts of Darius, king of Persia, and his son Xerxes, to enslave their European neighbours on the north and west shores of the Ægean; and it was no doubt as much for the advantage of his poetical faculty as for the development of his manhood, that he took an active part in those famous military achievements by which the march of the insolent Asiatic hosts was repelled. The father of Attic tragedy helped, in the year 490, to drive the captains of Darius into the marshes of Marathon, and, ten years later, encompassed with ruin the multitudinous armament of Xerxes, within the narrow strait of Salamis. The glories of this naval achievement, the hard who had helped to win it with his sword afterwards lived to celebrate with the lyre, and left to the world the play of The Persians, as a great national record of combined poetry and patriotism almost unique in history. Of his subsequent career at Athens, only a few scanty notices remain, and those chiefly connected with the representation of his plays. We know that he composed 70 plays, and that he gained the prize for dramatic excellence 13 times; further, that the Athenians esteemed his works so highly as to allow some of them to be represented after his death,—a privilege, in their dramatic practice, altogether anomalous. We know, also, that in the course of his life he paid one or two visits to Sicily, to which country he was attracted, no doubt, by the same literary influence in the person of its ruler Hiero, that drew thither Bacchylides, Simonides, and other notable men of that rich epoch. There can, at the same time, be little doubt that one cause of his visits to that island may have been a want of sympathy as to political matters between him and the Athenian public; for while the Athenians, from the time of Cleisthenes (A.C. 510), had been advancing by rapid and decided steps to the full expansion of the democratic principle, it is evident, from some passages in his plays, especially from the whole tone and tendency of the Eumenides, that the political leanings of the poet of the Prometheus were towards aristocracy, and that, in the days of Pericles, he foresaw, with a sorrowful fear, the ripeness of those democratic evils which within so short a period led Xenophon to seek a new fatherland in Sparta, and opened to the Macedonian a plain path to the sovereignty of Greece.
But whatever may have been his motives for retiring from Æschylus, the scene of so many literary triumphs (and the gossips of ancient times have of course transmitted to us their pleasant inventions on this point), it is certain that, in the year A.C. 456, two years after the representation of his great trilogy, The Orestiad, he died at Gela, in Sicily, in the 69th year of his age; and the people of Gela, rejoicing in his bones, as Ravenna does in those of the banished Dante, inscribed the following memorial on his tomb:—
"Here Æschylus lies, from his Athenian home
Remote, 'neath Gela's wheat-producing loam;
How brave in battle was Euphorion's son,
The long-haired Mede can tell who fell at Marathon."
And thus he lives among posterity, celebrated more as a patriot than as a poet; as if to witness to all times, that the great world of books, with all its power, is but a small thing unless it be the reflection of a greater world of action.
Of the seventy plays which an old biographer reports him to have composed, only seven remain, with a few fragments of little significance, save to the keen eye of the professed philologist. These fragments, however, are sufficient to justify the high esteem in which he was held by the Athenian public, and by that greatest of all the great wits of a witty age and a witty people, Aristophanes. In the grand trilogy which exhibits, in three consecutive tragedies, the story of the murder of Agamemnon, and its moral sequences, we have a perfect specimen of what the Greek tragedy was to the Greeks, as at once a complex artistic machinery for the exhibition of national legend, and a grave pulpit for the preaching of important moral truths; nor could a more worthy founder than Æschylus of such a "Sacred Opera" be imagined. His imagination dwells habitually in the loftiest region of the stern old religious mythology of primeval Greece; his moral tone is pure—his character earnest and manly—and his strictly dramatic power (notwithstanding the very imperfect form of the drama in his day), as exhibited more especially in the Agamemnon, in the Eumenides, and in some parts of the Prometheus, is such as none of his famous successors, least of all Euripides, could surpass. Of his other plays, the Seven against Thebes is a drama, as Aristophanes expressed it, "full of war," and breathes in every line the spirit of the age and of the people that saved Europe from the grasp of Oriental despotism; The Persians, though weak in some parts, contains some fine choral poetry, and a description of the battle of Salamis, that will belong to the poetry of the world so long as the world lasts; while The Suppliants presents much in a tasteful translation, that makes us lament the loss of the missing pieces of the trilogy to which it belonged, no less than the blundering of the thoughtless copyists of the middle ages, by whose pen it has been so egregiously defaced. For in ancient times the flowing rhetorical Euripides was found a more useful model for the schools of eloquence, than the lofty, stern, and sometimes harsh, and occasionally it may be obscure, Æschylus: therefore, the text of the latter has been comparatively neglected, and much work was left for the tasteful philologist, before many parts of his noblest choruses could be rendered legible. Of the editions of Æschylus, the most notable in the earlier times of modern scholarship is that of Stanley; in more recent times, that of Schütz, who undertook the work of restoration with much learning and great boldness. The impulse given by this scholar was moderated by Wellauer, who, in his edition, along with some happy emendations, principally endeavoured to vindicate the authority of the manuscript readings from the large license of conjectural critics; and now from the remains of the great Hermann, has been published a text that should present the just medium between the timidity of Wellauer, and the rashness of mere conjectural criticism. Of English poetical translations
Æsculapius there are only two; the old one by Potter, and a recent one by Blackie. There is also a translation in literal prose by Buckley. (J. S. B.)
ÆSCULAPIUS, in the Heathen Mythology, the god of physic, was the son of Apollo and the nymph Coronis. He was educated by the centaur Chiron, who taught him physic, by which means Æsculapius cured the most desperate diseases. But Jupiter, enraged at his restoring to life Hippolytus, who had been torn in pieces by his own horses, killed him with a thunderbolt. According to Cicero, there were three deities of this name; the first, the son of Apollo, worshipped in Arcadia, who invented the probe and bandages for wounds; the second, the brother of Mercury killed by lightning; and the third, the son of Arsippus and Arsinoe, who first taught the art of tooth-drawing and purging. At Epidaurus, Æsculapius's statue was of gold and ivory, with a long beard, his head surrounded with rays, holding in one hand a knotty stick, and the other entwined with a serpent; he was seated on a throne of the same materials as his statue, and had a dog lying at his feet. The Romans crowned him with laurel, to represent his descent from Apollo; and the Phliasians represented him as beardless. The cock, the raven, and the goat, were sacred to this deity. His chief temples were at Pergamus, Smyrna, Tricca, a city in Thessaly, and the isle of Coos; in all which votive tablets were hung up, showing the diseases cured by his assistance. But his most famous shrine was at Epidaurus, where, every five years, games were instituted to him, nine days after the Isthmian games at Corinth.
ÆSOP, the fabulist, was born about the year 620 B.C., but the place of his birth is uncertain, that honour being claimed alike by Samos, Sardis, Mesembria in Thrace, and Coticum in Phrygia. He was brought, while young, to Athens as a slave, and having served several masters, was eventually enfranchised by Iadmon the Samian. He thereupon visited Croesus king of Lydia, at whose court he is represented by Plutarch as reproving Solon for his discourteous manner towards the king. During the usurpation of Pisistratus, he is said to have visited Athens, and composed the fable of Jupiter and the Frogs for the instruction of the citizens (Phaedrus, i. 2). As the ambassador of Croesus at Delphi, he was charged with the distribution of the large sum of four minæ to each of the citizens; but, in consequence of some dispute, he returned the money to Croesus. The Delphians, incensed at his conduct, accused him of sacrilege, and threw him headlong from a precipice, about 564 B.C. A pestilence which ensued being attributed to this crime, the people declared their willingness to make compensation for his death; which in default of a nearer connection was claimed and received by Iadmon, the grandson of his old master. (Plut. de sera Num. Vind., p. 556. Herodot. ii. 134.) None of Æsop's works are extant. The popular stories regarding him are derived from a life prefixed to a book of fables purporting to be his, collected by Maximus Planudes, a monk of the fourteenth century, in which he is represented as a monster of ugliness and deformity, a notion utterly without foundation, and doubtless intended to heighten his wit by the contrast. That this life, however, was in existence a century before Planudes's time, appears by a manuscript of it found at Florence, and published in 1809. In Plutarch's Convivium, where Æsop is a guest, though there are many jests on his original servile condition, there are none on his appearance; and it would seem that the ancients were not usually restrained by delicacy in this point, since the personal defects of Socrates, and his resemblance to old Silenus, afford ample matter for merriment and raillery in the Symposium of Plato. We are told, besides, that the Athenians erected, in honour of Æsop, a noble statue by the famous sculptor Lysippus, a circum-
stance which alone were sufficient to confute the absurd fiction of his deformity: but more to the point is the statement of Pliny (xxxvi. 12.), that he was the Contubernalis of Rhodope, his fellow-slave, whose extraordinary beauty passed into a proverb:
Ἄσπας ὄμωσα, καὶ Ῥοδῶπις ἦ καλῇ.
The obscurity in which the history of Æsop is involved, has induced some to deny his existence altogether; and Giambattista Vico, in his Scienza Nuova, chooses rather to consider him as an abstraction,—an excess of scepticism which is quite unreasonable. Whether Æsop left any written fables, has been more justly disputed, and Bentley inclines to the negative. Thus Aristophanes (In Vespis, v. 1259) represents the old man as learning his fables in conversation, and not from a book; and Socrates essayed to versify such as he remembered (Plat. Phed. p. 61). Others again are of opinion, that a collection had been made of them before the time of Socrates. (Mus. Crit. i. 408.) It is, however, certain that fables bearing Æsop's name were popular at Athens during the most brilliant period of its literary history; though the discrepancies of authors in quoting the same fables seem in favour of Bentley's hypothesis. (Compare Aristot. De Part. Anim. iii. 2; and Lucian. Nigr. 32.) The original fables were in prose, and were turned into verse by several writers; the first, after the example of Socrates, being Demetrius Phalereus. Next appeared an edition in elegiac verse, often cited by Suidas, but the author's name is unknown; then Babrius, an excellent Greek poet, turned them into choliambics; but of ten books, a few fables only are preserved entire. Of the Latin writers of Æsopian fables, Phaedrus is the most celebrated.
“Æsopus auctor quam materiam reperit,
Hanc ego polivi versibus senarit.”
PHÆDR.
The fables now extant in prose under Æsop's name are entirely spurious, as proved by Bentley in his Dissertation on the Fables of Æsop, and have been assigned an oriental origin. The identification of Æsop with the Arabian philosopher and fabulist Lokman (who is made by some traditions the contemporary of the psalmist David), has frequently been attempted; and the Persian accounts of Lokman, which among other things describe him as an ugly black slave, appear to have been blended by the author of the Life published by Planudes, with the classical stories respecting Æsop. The similarity of the fables ascribed to each renders it probable that they were derived from the same Indo-Persian source, or from the Chinese, who appear to have possessed such fables in very remote antiquity. A complete collection of the Æsopian Fables, 231 in number, was published at Breslau, by J. G. Schneider, in 1810.
ÆSOP, a Greek historian, whose life of Alexander the Great is preserved in a Latin translation by Julius Valerius. It is a work of no credit, abounding in errors.
ÆSOP, Clodius, a celebrated actor, who flourished about the 670th year of Rome. He and Roscius were contemporaries, and the best performers who ever appeared upon the Roman stage; the former excelling in tragedy, the latter in comedy. Cicero put himself under their direction, to perfect his action. Æsop lived in a most expensive manner, and at one entertainment is said to have had a dish which cost above L.800. This dish, we are told, was filled with singing and speaking birds, some of which cost near L.50. The delight which Æsop took in this sort of birds proceeded, as M. Bayle observes, from the expense. He did not make a dish of them because they could speak, (according to the refinement of Pliny upon this circumstance,) this motive being only accidental, but because of their extraordinary price.
Æsthetics If there had been any birds that could not speak, and yet more scarce and dear than these, he would have procured such for his table. When he was upon the stage, he entered into his part to such a degree as sometimes to be seized with a perfect ecstasy. Plutarch mentions it as reported of him, that whilst he was representing Atreus deliberating how he should revenge himself on Thyestes, he was so transported beyond himself in the heat of action, that with his truncheon he smote one of the servants crossing the stage, and laid him dead on the spot. Æsop's son was no less luxurious than his father, for he dissolved pearls for his guests to swallow. Some speak of this as a common practice of his; but others mention his falling into this excess only on a particular day, when he was treating his friends. Horace1 lib. ii. 239, speaks only of one pearl of great value, which he dissolved in vinegar and drank.
1 Sat. iii. a particular day, when he was treating his friends. Horace lib. ii. 239, speaks only of one pearl of great value, which he dissolved in vinegar and drank.
ÆSTHETICS, a term derived from αἰσθητικός, "belonging to sensation," employed by the followers of the German metaphysicians to designate philosophical investigations into the theory of The Beautiful, or Philosophy of the Fine Arts, which they are disposed to regard as a distinct science. It was first used in this sense by Wolf, about the middle of last century; and Winckelmann, in his work on painting and sculpture, maintains that beauty is a special property of bodies. Similar views are maintained by Baumgarten and Schelling, who apply their general principles to poetry, painting, sculpture, architecture, and music. Æsthetic speculations do not appear to have contributed any thing to the improvement of the fine arts, or to our real knowledge of mental phenomena.
ÆSTIMATIO CAPITIS, a term met with in old law-books for a fine anciently ordained to be paid for offences committed against persons of quality, according to their several degrees.
ÆSTIVAL, in a general sense, denotes something connected with, or belonging to summer. Hence æstival sign, æstival solstice, &c.
ÆSTUARY, in Geography, denotes an arm of the sea, which runs a good way within land. Such is the Bristol channel, and many of the firths of Scotland.
ÆSTUARY, in ancient baths, a secret passage from the hypocaustum into the chambers.
ÆSTUARY, among Physicians, a vapour bath, or any other instrument for conveying heat to the body.
ÆSTUI, a people that dwelt on the sea-coast in the N.E. of Germany, whose manners are minutely described by Tacitus. In appearance and manners, says that author, they resemble the Suevi; their language, that of Britain. They worshipped the mother of the gods, in whose honour they wore images of the boar, as amulets in war; fighting chiefly with clubs, as they had little iron. They engaged in husbandry, and gathered amber for the Roman market. This substance they called glossina. Their name is still preserved in the modern Esthen, the German name of the Estonians. See Latham's Germania of Tacitus, p. 166. Ukert, vol. iii., pt. i., p. 420.
ÆSYMNETES, Ἀσυνήτης, among the Greeks, was, like the Roman dictator, a person invested by the people with absolute power for a limited period in great emergencies of the State. Such was Pittacus at Mytilene, or Dracon and Solon at Athens.—Arist. Polit. iii. iv.
ÆSYMNIIUM, in Antiquity, a monument erected to the memory of the heroes by Æsymnus the Megarean. On consulting the oracle in what manner the Megareans might be most happily governed, he was answered, By holding consultation with the more numerous. Taking this to signify the dead, he built the said monument, and a senate-house that embraced it within its compass, imagining that thus the dead would assist at their consultations.—Pausanias.
ÆETH. See ÆTH.
ÆTHALIA, or ILUA, in Ancient Geography, now Elba, an island on the coast of Etruria, in compass a hundred miles, abounding in iron. It was so called from αιθάλη, smoke, which issued from the shops of Vulcan.
ÆTHELING, or ÆDELING, the Anglo-Saxon title given to the children of kings and nobles. It is compounded of æthel, wel, illustrious, and ling, lmx, which, when affixed to persons, indicates diminution or adolescence.
ÆTHELSTAN. See ÆTHELSTAN.
ÆTHER is usually understood of a thin, subtle matter or medium, much finer and rarer than air, which, commencing from the limits of our atmosphere, possesses the whole heavenly space. The word is Greek, αιθήρ, supposed to be formed from the verb αιθω, to burn, to flame; some of the ancients, particularly Anaxagoras, supposing it to be of the nature of fire.
The philosophers cannot conceive that the largest part of the creation should be perfectly void; and therefore they fill it with a species of matter under the denomination of æther. But they vary extremely as to the nature and character of this æther. Some conceive it as a body sui generis, appointed only to fill up the vacancies between the heavenly bodies, and therefore confined to the regions above our atmosphere. Others suppose it of so subtle and penetrating a nature as to pervade the air and other bodies, and to possess the pores and intervals thereof. Others deny the existence of any such specific matter, and think the air itself, by that immense tenuity and expansion it is found capable of, may diffuse itself through the interstellar spaces, and be the only matter found therein.
In effect, æther being no object of our sense, but the mere work of imagination, brought only upon the stage for the sake of hypothesis, or to solve some phenomenon real or imaginary, authors take the liberty of modifying it as they please. Some suppose it of an elementary nature, like other bodies, and only distinguished by its tenuity, and the other affections consequent thereon; which is the philosophical æther. Others will have it of another species, and not elementary, but rather a sort of fifth element, of a purer, more refined, and spiritous nature, than the substances about our earth, and void of the common affections thereof, as gravity, &c. The heavenly spaces being the supposed region or residence of a more exalted class of beings, the medium must be more exalted in proportion. Such is the ancient and popular idea of æther, or æthereal matter.
The term æther being thus embarrassed with a variety of ideas, and arbitrarily applied to so many different things, the later and severer philosophers choose to set it aside, and in lieu thereof substitute otherwise determinate ones. Thus, the Cartesians use the term materia subtilis, which is their æther; and Sir Isaac Newton, sometimes a subtile spirit, as in the close of his Principia; and sometimes a subtile or æthereal medium, as in his Optics.
Heat, Sir Isaac Newton observes, is communicated through a vacuum almost as readily as through air; but such communication cannot be without some interjacent body, to act as a medium. And such body may be subtle enough to penetrate the pores of glass, and may permeate those of all other bodies, and consequently be diffused through all the parts of space.
The existence of such an æthereal medium being settled, that author proceeds to its properties; inferring it to be not only rarer and more fluid than air, but exceedingly more elastic and active; in virtue of which properties he shows, that a great part of the phenomena of nature may be produced by it. To the weight, e. g. of this medium, he attributes gravitation, or the weight of all other bodies; and to its elasticity, the elastic force of the air and of nervous fibres, and the