Year: 1874

NJ. JOubert has communicated to the
French Societe de la Navigation Aeri-
enne the following paper On a proposed
method of causing balloons to ascend
without throwing away ballast, or de-
scend without opening the valve:


M. CrOce-Spinelli has proposed to
the society the employment of little
helix with horizontal axis, managed by
the hand, which permits the aeronaut
to turn the balloon upon itself, or to
cause it to rest immovable in resisting
rotation. And the members of the So
ciety, taking into consideration the
slight degree of force necessary to turn
a spherical balloon upon its own axis,
consider that this screw, operated by
the hand, would be sufficient for the
purpose. Now, from this possibility of
turning balloon, have dedRced an
application, which I consider q practi-
cal one, for causing balloon to ascend
or descend at will. Everybody knows
the action of the rays of the sun upon
balloons and they further know that
this action varies considerably accord
ing as the stuff of which the balloons
are made is white, black, or intermedi-
ate tints. Suppose, then, that we di-
N4SS fltC SaS-bbsS 41bO b"D GhlEpICTSs
perpendicularly that is from the valve
down to the neck, and that one of these
hemispheres be black and the other
white,


We know that the black hemisphere
will absorb the rays of the sun, and
thds cause the expansion of the gas,
and the consequent rising of the balloon
to much greater extent than the white
hemisphere. If, then, by the action Of
the little screw we present the black
hemisphere to the sun, the gas rarefes
and the balloon ascends. If, on the
contrary, we turn the white hemisphere
to the sun, the absorption of its heat
is much less considerable, and in the
mean time the radiation which is GER
tain to take place from the black por-
tiOn of the balloon will cause a conden-
satiOn of the gas, and the balloon de-
scends. Finally, if-the balloon pre-
sents side to the sun which is half
black and half white, the action and re-
action will be equal, and the balloon
will remain motionless-that is, so far
as vertical motion is concerned. In re-
gard to Montgolfera, the employment
of an envelope half black and half
white might be expected to give very
interesting results. NJ. Sivel has told
US that Mr.. Wells, having ascended
from Rome in Montgolfer during the
hot season, was enabled to remain
several hours in the air without
replenishing the fire. The suns rays
darting upon the balloon were alone
sufficient to maintain the heat of the
air in its interior. This behavior of
Montgolifers, and the possibility of
their being kept aIoft in part by the
heat of the sun, would seem to prom
ise excellent results in hot countries, if
it were possible to regulate and moder-
ate solar action. This end would be at
tanned with a particolored envelope,
since the aeronaut who ascends in q
Montgolifer has the power of present
ing to the sun, at will, either a surface
which absorsb or one which repels the
suns rays. M. Jules Verne, in his clever
romance of "Five Weeks in Balloon" :"
relates the fictitious adventures of
party of aeronauts vino crossed the CEN
ire of Africa in the air. 1t seems to me
that this pretty fiction might be made a
reality through the medium of q grand
white and black Montgolfier, in which
the heat furnished by a petroleum fur
mace would be considerably augmented
by the action of the tropical sun.