A Project for Flying | Page 7

interposition of a
metallic covering; as for instance, by gilding the Balloon, which would
be effectual could it be contrived to endure the constant friction and
bending of the material itself.]
Beneath the centre of the Balloon, and about two-thirds of its length, is
a frame of light wood, answering to the hoop of an ordinary Balloon; to
which are attached the cords of the net which encloses the suspending
vessel, and which serves to distribute the pressure of the appended
weight equally over its whole surface, as well as to form an
intermediate means of attachment for the rest of the apparatus. This
consists of a car or basket in the centre; at one end the rudder, and at
the other the Archimedean Screw. The car is about two feet long and
eighteen inches broad, and is laced to the hoop by cords, which running
through loops instead of being fastened individually, allow of unlimited
play, and equalize the application of the weight of the car to the hoop,
as of the whole to the Balloon above. The Archimedean Screw consists
of an axis of hollow brass tube eighteen inches in length, through
which, upon a semi-spiral of 15° of inclination, are passed a series of
radii or spokes of steel wire, two feet long, (thus projecting a foot on
either side) and which being connected at their outer extremities by two
bands of flattened wire, form the frame work of the Screw, which is
completed by a covering of oiled silk cut into gores, and tightly
stretched, so as to present as nearly uniform a surface as the nature of
the case will permit. This Screw is supported at either end of the axis
by pillars of hollow brass tube descending from the hoop, in the lower
extremities of which are the holes in which the pivots of the axis
revolve. From the end of the axis which is next the car, proceeds a shaft
of steel, which connects the Archimedean Screw with the pinion of a
piece of spring machinery seated in the car; by the operation of which it
is made to revolve, and a progressive motion communicated to the
whole apparatus. This spring is of considerable power compared with
its dimensions, being capable of raising about 45 pounds upon a barrel
of four inches diameter after the first turn, and gradually increasing as it
is wound up. It weighs altogether, eight pounds six ounces.

The rudder is a light frame of cane covered with silk, somewhat of the
form of an elongated battledoor, about three feet long, and one foot
wide, where it is largest. It might be made considerably larger if
required, being exceedingly light and yet sufficiently strong for any
force to which it could be subjected. It weighs altogether only two
ounces and a half. This instrument possesses a double character.
Besides its proper purpose of guiding the horizontal course of the
Balloon, it is capable of being applied in a novel manner to its elevation
or depression, when driven by the propulsive power of the Screw.
Being so contrived as to be capable of being turned flat, and also
directed upwards or downwards as well as to the right or left, it enables
the aeronaut to transfer the resistance of the air, which, in any inclined
position, it must generate in its passage, to any side upon which he may
desire to act, and thus give a determination to the course of the Balloon
in the opposite direction. This will appear more clear as well as more
certain when we consider, that the aerial vessel being in a state of
perfect equipoise, as it ever must be when proceeding on the same level,
the slightest alteration in its buoyancy is sufficient to send it to a
considerable distance either up or down as the case may be: the
rejection of a pound of ballast, or of an equivalent amount of gas, being
enough to conduct the aeronaut to the extremest limits of his desires in
either direction, whatever may be the size of his Balloon. Now a
resistance equal to many pounds is attainable by an inclined plane of
even moderate dimensions when propelled even with moderate velocity;
and being readily governed by the mere inclination of the impinging
plane at the will and by the hand of the aerial voyager, it will be in his
power to vary the level of his machine with very considerable nicety;
enabling him to approach the surface of the earth, or in a gentle curve
to sweep away from its occasional irregularities, and proceed to a very
considerable elevation without interrupting the progress of his course,
and, what is of more importance, without sacrificing any part of his
resources in gas or ballast, upon the