Wonderfull Balloon Ascents
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Fulgence Marion >> Wonderfull Balloon Ascents
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Afterwards comes Cyrano of Bergerac, who promulgates five
different means of flying in the air. First, by means of phials
filled with dew, which would attract and cause to mount up.
Secondly, by a great bird made of wood, the wings of which should
be kept in motion. Thirdly, by rockets, which, going off
successively, would drive up the balloon by the force of
projection. Fourthly, by an octahedron of glass, heated by the
sun, and of which the lower part should be allowed to penetrate
the dense cold air, which, pressing up against the rarefied hot
air, would raise the balloon. Fifthly, by a car of iron and a
ball of magnetised iron, which the aeronaut would keep throwing
up in the air, and which would attract and draw up the balloon.
The wiseacre who invented these modes of flying in the air seems,
some would say, to have been more in want of very strict
confinement on the earth than of the freedom of the skies.
In 1670 Francis Lana constructed the flying-machine shown on the
next page. The specific lightness of heated air and of hydrogen
gas not having yet been discovered, his only idea for making his
globes rise was to take all the air out of them. But even
supposing that the globes were thus rendered light enough to
rise, they must inevitably have collapsed under the atmospheric
pressure.
As for the idea of making use of a sail to direct the balloon, as
one directs a vessel, that also was a delusion; for the whole
machine, globes and sails, being freely thrown into the air,
would infallibly follow the direction of the wind, whatever that
might be. When a ship lies in the sea, and its sails are
inflated with the wind, we must remember that there are two
forces in operation--the active force of the wind and the passive
force of the resistance of the water; and in working these forces
the one against the other, the sailor can turn within a point of
any direction he pleases. But when we are subjected wholly to a
single force, and have no point of support by the use of which to
turn that force to our own purposes, as is the case with the
aeronaut, we are entirely at the mercy of that force, and must
obey it.
After the flying-machine of Lana there was constructed by Galien
(who, like the former, was an ecclesiastic) an air-boat, less
chimerical in its form, looked at in view of the conditions of
aerial navigation, but much more singular. Galien describes his
air-boat, in 1755, in his little work entitled, "The Art of
Sailing in the Air." His project was a most extraordinary one,
and its boldness is only equalled by the seriousness of the
narrative. According to him, the atmosphere is divided into two
horizontal layers, the upper of which is much lighter than the
lower. "But," says Galien, "a ship keeps its place in the water
because it is full of air, and air is much lighter than water.
Suppose, then, that there was the same difference of weight
between the upper and the lower layer of air as there is between
the lower stratum and water; and suppose, also, a boat which
rested upon the lower layer of air, with its bulk in the lighter
upper layer--like a ship which has its keel in the water but its
bulk in the air--the same thing would happen with the air-ship as
with the water-ship--it would float in the denser layer of air."
Galien adds that in the region of hail there was in the air a
separation into two layers, the weights of which respectively are
as 1 to 2. "Then," says he, "in placing an air-boat in the region
of hail, with its sides rising eighty-three fathoms into the
upper region, which is much more light, one could sail
perfectly."
But how to get this enormous air-boat up to the region of hail?
This is a minor detail, respecting which Galien is not clear.
From the labours of Lana and Galien, with their impossible flying
machines, the inventor of the balloon could derive no benefit
whatever; nor is his fame to be in the least diminished because
many had laboured in the same field before him. Nor can the story
of the ovoador, or flying man, a legend very confused, and of
which there are many versions, have given to Montgolfier any
valuable hints. It appears that a certain Laurent de Guzman, a
monk of Rio Janeiro, performed at Lisbon before the king, John
V., raising himself in a balloon to a considerable height. Other
versions of the story give a different date, and assign the
pretended ascent to 1709. The above engraving, extracted from
the "Bibliotheque de la Rue de Richelieu," is an exact copy of
Guzman's supposed balloon.
In 1678 a mechanician of Salle, in Maine, named Besnier invented
a flying-machine. The machine consisted of four great wings, or
paddles, mounted at the extremities of levers, which rested on
the shoulders of the man who guided it, and who could move them
alternately by means ,of his hands and feet. The following
description of the machine is given in the Journal de Paris by an
eye-witness:
"The 'wings' are oblong frames, covered with taffeta, and
attached to the ends of two rods, adjusted on the shoulders The
wings work up and down. Those in front are worked by the hands;
those behind by the feet, which are connected with the ends of
the rods by strings. The movements were such that when the right
hand made the right wing descend in front, the left foot made the
left wing descend behind; and in like manner the left hand in
front and the right foot behind acted together simultaneously.
This diagonal action appeared very well contrived; it was the
action of most quadrupeds as well as of man when walking; but the
contrivance, like others of the same kind, failed in not being
fitted with gearing to enable the air traveller to proceed in any
other direction than that in which the wind blew him. The
inventor first flew down from a stool, then from a table,
afterwards from a window, and finally from a garret, from which
he passed above the houses in the neighbourhood, and then,
moderating the working of his machine, he descended slowly to the
earth."
Tradition records that under Louis XIV. a certain rope-dancer,
named Alard, announced that on a certain day he would perform the
feat of flying in the air. We have no description of his wings.
It is recorded, however, that he set out on his adventurous
flight; but he had not calculated all the necessities of the
case, and, falling to the ground, he was dangerously hurt.
Leonardo da Vinci might have known the art of flying in the air,
and might even have practiced it. A statement to this effect, at
least, is found in several historians. We have, however, no
direct proof of the fact.
The Abbe Deforges, of Etampes, announced in the journals in 1772
that he would perform the great feat. On the appointed day
multitudes of the curious flocked to Etampes. The abbe's machine
was a sort of gondola, seven feet long and about two feet deep.
Gondola conductor, and baggage weighed in all 213 pounds. The
pious man believed that he had provided against everything.
Neither tempest nor rain should mar his flight, and there was no
chance of his being upset; whilst the machine, he had decided,
was to go at the rate of thirty leagues an hour.
The great day came, and the abbe, entering his air-boat amidst
the applause of the spectators, began to work the wings with
which it was provided with great rapidity. "But," says one who
witnessed the feat, "the more he worked, the more his machine
cleaved to the earth, as if it were part and parcel of it."
Retif de la Bretonne, in his work upon this subject, gives the
accompanying picture of a flying man, furnished with very
artistically designed wings, fitting exactly to the shoulders,
and carrying a basket of provisions, suspended from his waist;
and the frontispiece of the "Philosophic sans Pretention" is a
view of a flying-machine. In the midst of a frame of light wood
sits the operator, steadying himself with one hand, and with the
other fuming a cremaillere, which appears to give a very quick
rotatory movement to two glass globes revolving upon a vertical
axis. The friction of the globes is supposed to develop
electricity to which his power of ascending is ascribed.
To wings, however, aerial adventurers mostly adhered. The
Marquis de Racqueville flew from a window of his hotel, on the
banks of the Seine, and fell into a boat full of washerwomen on
the river. All these unfortunate attempts were lampooned,
burlesqued on the stage, and pursued with the mockery of the
public.
Up to this time, therefore, the efforts of man to conquer the air
had miscarried. They were conducted on a wrong principle, the
machinery employed being heavier than the air itself But, even
before the time of Montgolfier, the principles of aerostation
began to be recognised, though nothing was actually done in the
way of acting upon them. Thus, in 1767, Professor Black, of
Edinburgh, announced in his class that a vessel, filled with
hydrogen, would rise naturally in the air; but he never made the
experiment, regarding the fact as capable of being employed only
for amusement. Finally, Cavallo, in 1782, communicated to the
Royal Society of London the experiments he had made, and which
consisted in filling soap-bubbles with hydrogen. The bubbles
rose in the atmosphere, the gas which filled them being lighter
than air.
Chapter III. The Theory of Balloons.
A certain proposition in physics, known as the "Principle of
Archimedes," runs to the following effect:--"Every body plunged
into a liquid loses a portion of its weight equal to the weight
of the fluid which it displaces." Everybody has verified this
principle, and knows that objects are much lighter in water than
out of it; a body plunged into water being acted upon by two
forces--its own weight, which tends to sink it, and resistance
from below, which tends to bear it up. But this principle
applies to gas as well as to liquids--to air as well as to water.
When we weigh a body in the air, we do not find its absolute
weight, but that weight minus the weight of the air which the
body displaces. In order to know the exact weight of an object,
it would be necessary to weigh it in a vacuum.
If an object thrown into the air is heavier than the air which it
displaces, it descends, and falls upon the earth; if it is of
equal weight, it floats without rising or falling; if it is
lighter, it rises until it comes to a stratum of air of less
weight or density than itself. We all know, of course, that the
higher you rise from the earth the density of the air diminishes.
The stratum of air that lies upon the surface of the earth is the
heaviest, because it supports the pressure of all the other
strata that lie above. Thus the lightest strata are the highest.
The principle of the construction of balloons is, therefore, in
perfect harmony with physical laws. Balloons are simply globes,
made of a light, air-tight material, filled with hot air or
hydrogen gas which rise in the air because (they are lighter than
the air they displace.
The application of this principle appeared so simple, that at the
time when the news of the invention of the balloon was spread
abroad the astronomer Lalande wrote--"At this news we all cry,
'This must be! Why did we not think of it before?'" It had been
thought of before, as we have seen in the last chapter, but it is
often long after an idea is conceived that it is practically
realised.
The first balloon, Montgolfier's, was simply filled with hot air;
and it was because Montgolfier exclusively made use of hot air
that balloons so filled were named Montgolfiers. Of course we
see at a glance that hot air is lighter than cold air, because it
has become expanded and occupies more space--that is to say, a
volume of hot air contains actually less air than a volume of the
same size of air that has not been heated. The difference
between the weight of the hot air and the cold which it displaced
was greater than the weight of tire covering of the balloon.
Therefore the balloon mounted.
And, seeing that air diminishes in density the higher we ascend,
the balloon can rise only to that stratum of air of the same
density as the air it contains. As the warm air cools it gently
descends. Again, as the atmosphere is always moving in currents
more or less strong, the balloon follows the direction of the
current of the stratum of air in which it finds itself.
Thus we see how simply the ascent of Montgolfiers, and their
motions, are explained. It is the same with gas-balloons. A
balloon, filled with hydrogen gas, displaces an equal volume of
atmospheric air; but as the gas is much lighter than the air, it
is pushed up by a force equal to the difference of the density of
air and hydrogen gas. The balloon then rises in the atmosphere
to where it reaches layers of air of a density exactly equal to
its own, and when it gets there it remains poised in its place.
In order that it may descend, it is necessary to let out a
portion of the hydrogen gas, and admit an equal quantity of
atmospheric air; and the balloon does not come to the ground till
all, or nearly all, the gas has been expelled and common air
taken in. Balloons inflated with hydrogen gas are almost the
only ones in use at the present day. Scarcely ever is a
Montgolfier sent up. There are aeronauts, however, who prefer a
journey in a Montgolfier to one in a gas-balloon. The air
voyager in this description of balloon had formerly many
difficulties to contend with. The quantity of combustible
material which he was bound to carry with him; the very little
difference that there is between the density of heated and of
cold air; the necessity of feeding the fire, and watching it
without a moment's cessation, as it hangs in the rechaud over the
middle of the car, rendered this sort of air travelling subject
to many dangers and difficulties. Recently, M. Eugene Godard has
obviated a portion of this difficulty by fitting a chimney, like
that which is found of such incalculable service in the case of
the Davy lamp. It is principally on account of this improvement
that the Montgolfiere has risen so highly in popular esteem.
Generally it is not pure hydrogen that is made use of in the
inflation of balloons. Aeronauts content themselves with the gas
which we burn in our streets and houses, and thus it suffices, in
inflating the balloon, to obtain from the nearest gas-works the
quantity of gas necessary, and to lead it, by means of a pipe or
tube, from the gasometer to the mouth or neck of the machine.
The balloon is made of long strips of silk, sewn together, and
rendered air-tight by means of a coating of caoutchouc. A valve
is fitted to the top, and by means of it the aeronaut can descend
to the earth at will, by allowing some quantity of the gas to
escape. The car in which he sits is suspended to the balloon by
a network, which covers the whole structure. Sacks of sand are
carried in this car as ballast, so that, when descending, if the
aeronaut sees that he is likely to be precipitated into the sea
or into a lake, he throws over the sand, and his air-carriage,
being thus lightened, mounts again and travels away to a more
desirable resting-place. The idea of the valve, as well as that
of the sand ballast, is due to the physician Charles. They
enable the aeronaut to ascend or descend with facility. When he
wishes to mount, he throws over his ballast; when he wants to
come down, he lets the gas escape by the valve at the roof of the
balloon. This valve is worked by means of a spring, having a long
rope attached to it, which hangs down through the neck to the
car, where the aeronaut sits.
The operation of inflating a balloon with pure hydrogen is
represented in the engraving on the next page.
Shavings of iron and zinc, water, and sulphuric acid, occupy a
number of casks, which communicate, by means of tubes, with a
central cask, which is open at the bottom, and is plunged in a
copper full of water. The gas is produced by the action of the
water and the sulphuric acid upon the zinc and the iron this is
hydrogen mixed with sulphuric acid. In passing through the
central copper, or vat, full of water, the gas throws off all
impurities, and comes, unalloyed with any other matter, into the
balloon by a long tube, leading from the central vats. In order
to facilitate the entrance of the gas into the balloon two long
poles are erected. These are furnished with pulleys, through
which a rope, attached also to a ring at the top of the balloon,
passes. By means of this contrivance the balloon can be at once
lightly raised from the ground, and the gas tubes easily joined
to it. When it is half full it is no longer necessary to suspend
the balloon; on the contrary, it has to be secured, lest it
should fly off. A number of men hold it back by ropes; but as
the force of ascension is every moment increasing, the work of
restraining the balloon is most difficult and exciting. At
length, all preparations being complete, the car is suspended,
the aeronaut takes his seat, the words "Let go all!" are shouted,
and away goes the silken globe into space.
The balloon is never entirely filled, for the atmospheric
pressure diminishing as it ascends, allows the hydrogen gas to
dilate, in virtue of its expansive force, and, unless there is
space for this expansion, the balloon is sure to explode in the
air.
An ordinary balloon, with a lifting power sufficient to carry up
three persons, with necessary ballast and materiel, is about
fifty feet high, thirty-five feet in diameter' and 2,250 cubic
feet in capacity. Of such a balloon, the accessories--the skin,
the network, the car--would weigh about 335 lbs.
To find out the height at which he has arrived, the aeronaut
consults his barometer. We know that it is the pressure of the
air upon the cup of the barometer that raises the mercury in the
tube. The heavier the air is, the higher is the barometer. At
the level of the sea the column of mercury stands at 32 inches;
at 3,250 feet--the air being at this elevation lighter--the
mercury stands at 28 inches; at 6,500 feet above sea level it
stands at 25 inches; at 10,000 feet it falls to 22 inches; at
20,000 feet to 15 inches. These, however, are merely the
theoretic results, and are subject to some slight variation,
according to locality, &c.
Sometimes the aeronaut makes his descent by means of the
parachute, a separate and distinct contrivance. If, from any
cause, it appears impracticable to effect a descent from the
balloon itself, the parachute may be of the greatest service to
the voyager at the present day it is chiefly used to astonish the
public, by showing them the spectacle of a man who, from a great
elevation in the air, precipitates himself into space, not to
escape dangers which threaten him in his balloon, but simply to
exhibit his courage and skill. Nevertheless, parachutes are
often of great actual use, and aeronauts frequently attach them
to their balloons as a precautionary measure before setting out
on an aerial excursion.
The shape of a parachute, shown on the previous page, very much
resembles that of the well-known all serviceable umbrella. The
strips of silk of which it is formed are sewn together, and are
bound at the top around a circular piece of wood. A number of
cords, stretching away from this piece of wood, support the car
in which the aeronaut is carried. At the summit is contrived an
opening, which permits the air compressed by the rapidity of the
descent to escape without causing damage to the parachute from
the stress to which it is subjected.
The rapidity of the descent is arrested by the large surface
which the parachute presents to the air. When the aeronaut
wishes to descend by the parachute, all that is required is,
after he has slipped down from the car of the balloon to that of
the parachute, to loosen the rope which binds the latter to the
former, which is done by means of a pulley. In an instant the
aeronaut is launched into space with a rapidity in comparison
with which the wild flights of the balloon are but gentle
oscillations. But in a few moments, the air rushing into the
folds of the parachute, forces them open like an umbrella, and
immediately, owing to the wide surface which this contrivance
presents to the atmosphere, the violence of the descent is
arrested, and the aeronaut falls gently to the ground, without
receiving too rude a shock.
The virtues of the parachute were first tried upon animals.
Thus, Blanchard allowed his dog to fall in one from a height of
6,500 feet. A gust of wind caught the falling parachute, and
swept it away up above the clouds. Afterwards, the aeronaut in
his balloon fell in with the dog in the parachute, both of them
high up in the cloudy reaches of the sky, and the poor animal
manifested by his barking his joy at seeing his master. A new
current separated the aerial voyagers, but the parachute, with
its canine passenger, reached the ground safely a short time
after Blanchard had landed from his balloon.
Experience has proved that, in the case of a descending
parachute, if the rapidity of the descent is doubled the
resistance of the air is quadrupled; if the rapidity is triple
the resistance is increased ninefold; or, to speak in language of
science, the resistance of the air is increased by the square of
the swiftness of the body in motion. This resistance increases
in proportion as the parachute spreads, and thus the uniformity
of its fall is established a minute after it has been disengaged
from the balloon. We can, therefore, check the descent of a body
by giving it a surface capable of distension by the action of the
air.
Garnerin, in the year 1802, conceived the bold design of letting
himself fall from a height of 1,200 feet, and he accomplished the
exploit before the Parisians. When he had reached the height he
had fixed beforehand, he cut the rope which connected the
parachute with the balloon. At first the fall was terribly
rapid; but as soon as the parachute spread out the rapidity was
considerably diminished. The machine made, however, enormous
oscillations. The air, gathering end compressed under it, would
sometimes escape by one side sometimes by the other, thus shaking
and whirling the parachute about with a violence which, however
great, had happily no unfortunate effect.
The origin of the parachute is more remote than is generally
supposed, as there was a figure of one which appeared among a
collection of machines at Venice, in 1617.
Another species of parachute, less perfect, to be sure; than that
of Garnerin, but still a practical machine, was described 189
years before the great aeronaut's feat at Paris. We read in the
narrative of the ambassador of Louis XIV at Siam, at the end of
the seventeenth century, the following passage--"A mountebank at
the court of the King of Siam climbed to the top of a high
bamboo-tree, and threw himself into the air without any other
support than two parasols. Thus equipped, he abandoned himself to
the winds, which carried him, as by chance, sometimes to the
earth, sometimes on trees or houses, and sometimes into the
river, without any harm happening to him."
Is not this the idea of our parachutes?
Chapter IV. First Public Trial of the Balloon.
(Montgolfier's Balloon Annonay, 5th of June of 1783.)
We are accustomed to rank the brothers Joseph and Etienne
Montgolfier as equally distinguished in the field of science.
The reason for thus associating these two names seems to have
been the fraternal friendship which subsisted in an extraordinary
degree in the Montgolfier family, rather than any equality of
claim which they had to the notice of posterity. After special
investigation, we find that Joseph Montgolfier was very superior
to his brother, and that it is to him principally, if not
exclusively, that we owe the invention of aerostation.
Nevertheless, we shall not insist upon this fact; and seeing that
a sacred amity always cemented a perfect union in the Montgolfier
family, we will regard that union as unbroken in any sense, and
will not insinuate that the brother of Montgolfier was
undeserving of the honoured rank which in his lifetime he held.
In 1783, the sons of Pierre Montgolfier, a rich papermaker at
Annonay department of Ardeche, were already in the prime of life,
and it is related of them that their principal occupation was
experimenting in the physical sciences. Joseph Montgolfier,
after being convinced by a number of minor experiments made in
1782 and 1783, that a heat of 180 degrees rarefied the air and
made it occupy a space of TWICE the extent it occupied before
being heated--or, in other words, that this degree of heat
diminished the weight of air by one half--began to speculate on
what might be the shape and the material of a structure which
being filled with air thus heated, would be able to raise itself
from the earth in spite of the weight of its own covering.
His first balloon was a small parallelopiped in very thin
taffeta, containing less than seventy-eight cubic inches of air.
He made it rise to the roof of his apartment in November,
1782--at Avignon, where he then happened to be. Having returned
some little time after to Annonay,
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