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172
Wonderful Balloon Ascents; Or, The Conquest of the Skies
·
Fulgence Marion
24
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.
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