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London, England, 1836-09-27 00:00:00

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The subjoined extracts from Armoires sur les iie:
rostats, par Meunier, Men:bre de r Acadenzie des
if Sciences, may amuse our readers who take an interest
in aerostation. Dr. Franklin, on the appearance of
the first balloons, observed that this new offspring of
the sciences should be carefully NI, atched in its infancy,
in the expectation of deriving advantage from it in a
Istate of maturity. It is looked upon at the present
day with indifference, and considered only as an object
of curiosity, reserved for the pomp of fetes. That,
however, was not the view taken when the first aeros-
tatic experiments were made. The memoir of Men-
-1 nier upon this subject was never printed, but Colonel
Coutelle, an old officer, who had the management of
the military balloons during the Republican revolution
of France, gave the public, in 1826, an analysis of it.
A notice of it appeared in the Revue Encyclopedique,
from which we extract the following remarks :
" Meunier, in his researches respecting balloons, pro:
posed nothing less than to make these machines capa-
ble of accomplishing long and distant voyages ; he
therefore calculated the best mesms of making them
strong enough to stand the shock of various cur-
rents which agitate the atmosphere. He project-
ed the power of throwing out anchors, of rising to
the elevation which might be necessary, of moving
through the air in a tranquil state, and of modifying
the direction and velocity of the machine. As the
envelopes which formed balloons could not be made
impenetrable to hydrogen, it became necessary to find
the means of preserving the gas, and of supplying the
deficiency occasioned by its escape. After finding,
Satisfactory answers to his scientific inquiries, it re-
mained to ascertain the form and dimensions of a
balloon capable of transporting, in addition to its
rigging, a crew for the necessary manceuvres, the
navigators, and their instruments, and a quantity of
provisions proportioned to the duration of a long
navigation through regions in which nothing could be
i found for the support of the travellers. In short, he
projected the construction of *an air-balloon- with the
' power required. This able mechanic overcame nearly
all the difficulties in his way by the invention of a
second envelope to his balloon. This addition pro-
cured him the means of resisting the violence of )vinds,
the facility of mounting and descending, and of keep-
ing at the desired elevation, in short, he avoided the
loss of hydrogen gas, or rendered the effect of so little
importance, that it might be neglected without incon-
venience. These results, so important, were entirely
dependent on the managers of the balloon.
" The hydrogen," says the author, " is contained
in a balloon of silk, plastered with caoutchouc (gum
elastic). This envelope must be as light as possible,
and greater than the volume of gas it is to contain.
The second envelope is also of silk, more 'expansive
than the balloon, and fortified upon the exterior by a
net. It should be impenetrable to the compressed at-
mospheric air, because it is well known that this fluid
is confined with less difficulty than the hydrogen. It
is plastered like the balloon, and capable of resisting
the more weighty pressure of air. They leave between
the two envelopes a 'space for the use we shall describe.
A tube, made of the same sort of• silk, is made to
communicate frcm this envelope with a pump in the
gondola or car. By the means of this pump they can
condense the air between the two envelopes, and dimi-
nish the volume of hydrogen, and also augment the
specific gravity of the fluid in the balloon. Thus,
when the aeronauts are at a great height, in order to
descend they have only to work the . pump. The
atmospheric air introduced between the envelopes
finds its way into the balloon, which in that pro-
cess can only maintain its equilibrium in a denser
atmosphere, and consequently it descends. By this
process the gas is secured, which can only serve
once if let out to descend. If they wish to rise again,
they have only to open a valve and let out the atmos-
pheric air detained between the two envelopes. To
descend they recommenced the compression of air. To
move horizontally in tranqUil air, Meunier employed
no other force than the arms of the crew. The author '
of the fifenzoire invented oars inclined like the sails of
a windmill, fixed to an horizontal axis, which the
crew turned. This mechanism procured but a slow
movement, something less than a league an honr. It
could be of little use, unless it became the means of
directing the balloon during its ascensional process into
a current of air, which would carry the aeronauts to-
wards the point of destination. He had no project
for carrying the balloon to the place of destination by
the action of oars alone. We see, in this attempt,
that the mechanist began his task upon the principles
of geometry. His object was to give stability to the
balloon, and make all the parts of the machine capa-
ble of meeting the difficulties it had to resist in mov-
ilia- through the air."
r•Monge, another mathematician, taking advantage of
the means projected by Meunier for mounting and de-
scending with great rapidity, conceived the possibility
of drawing from a vertical Movement, that of horizontal
translation. Meunier, like our countryman Green,
employed only one balloon for transporting all his tra-
vellers. Monge divided them in no less than twenty-
five small balloons, each retaining a spherical figure
instead of the elliptical form chosen by Meunier.
Monge attached his balloons one to the other, so that
in mounting they presented a flexible assemblage, sus-
ceptible of being developed in a right line or curve.
This system of globes rising and descending with the
rapidity which the aeronauts calculated upon would
have imitated in the air the movement of the serpent
or eel in the water. It is a subject of regret that this
illustrious geometrician did not try experiments founded
upon his first ideas, and submit his plan to calculation.
The rest of Meunier's Memoir is devoted to details
of execution and calculation of expenses, matters which
do not excite the curiosity of the reader, but which, in
fact, often cost the author more labour than all the
rest of his plan. The balloons proposed by Meunier
would have been expensive, but that might have been
overlooked. They are dear articles at the present day,
consequently in the first experiments for the establish-
ment of an invention of high importance, a little ex-
pense could not be said to be useless, In some
matters of public utility it may be necessary to shut
our eyes and onen our purses.
BALLOON TELEGRAPHS.
After the violent storms of the revolution had
ceased, and learned men were no longer in dread
of being dragged to the scaffold, they began to
breathe ; hope revived, and they saw an opening in
the future. They calculated tile time when France
might be happy and free, but liberty was only to be
o
gained by victory. Europe in arms,_ deniedl the French
nation those rights which they clannu, and which
belonged to the people. The organization of the army,
providing for its wants, concerting operations, the
establishment of safe and rapid correspondence, and,
in short, all that could contribute to public safety,
then occupied the mind of almost every Frenchman.
Among st other inventions, they proposed moveable
telegraphic lines, and signals were stationed on points
proper for the protection of the nation. Air balloons
were considered the most effectual means of raising
signals to an elevation at which they might
notwithstanding the interposition be seen,
0
objects which intercept the view,
woods and all the
i
with high mountains ; but theyn countries covered
anceuvre, and make required persons to
m
commutncations. The
employed, though sim oe,
1,. were perhaps not the
they became useless •means
in stroll,* ales ofwind, best
and by
the failure of one b
signal posto the whole ielegraphiqzte
line was reduced to silence. The teleeraph used
on the occasion was composed of Seven cylinders or
light drums, formed by dark cloth
~
They
were
wood, conse-
fastened to hoops.
suspended to a triangle of
luently, the hoops were horizontal and the axis ofthe.
drum vertical. A block and line from each drum en-
abled men below to work the machine, and suffer it to