Various interesting experiments have been made with a view to
utilizing luminous captive balloons for optical communications. As we
have already seen, this maybe effected by using opaque balloons, and
throwing upon them at unequal intervals a luminous fascicle by means
of a projector. As for using a luminous source placed in the car of a
balloon, that cannot be thought of in the present state of aeronautic
science; the continual rotation of the balloon around its axis would
render the projection and reception of the signals in a given
direction impossible.