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172
Wonderful Balloon Ascents; Or, The Conquest of the Skies
·
Fulgence Marion
22
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.
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