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length, through which, upon a semi-spiral inclined at fifteen degrees,
pass a series of steel wire radii, two feet long, and thus projecting a
foot on either side. These radii are connected at the outer extremities
by two bands of flattened wire--the whole in this manner forming the
framework of the screw, which is completed by a covering of oiled silk
cut into gores, and tightened so as to present a tolerably uniform
surface. At each end of its axis this screw is supported by pillars of
hollow brass tube descending from the hoop. In the lower ends of these
tubes are 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, connecting
the screw with the pinion of a piece of spring machinery fixed in the
car. By the operation of this spring, the screw is made to revolve with
great rapidity, communicating a progressive motion to the whole. By
means of the rudder, the machine was readily turned in any direction.
The spring was of great power, compared with its dimensions, being
capable of raising forty-five pounds upon a barrel of four inches
diameter, after the first turn, and gradually increasing as it was wound
up. It weighed, altogether, eight pounds six ounces. The rudder was
a light frame of cane covered with silk, shaped somewhat like a
battle-door, and was about three feet long, and at the widest, one foot.
Its weight was about two ounces. It could be turned flat, and directed
upwards or downwards, as well as to the right or left; and thus enabled
the æronaut to transfer the resistance of the air which in an inclined
position it must generate in its passage, to any side upon which he
might desire to act; thus determining the balloon in the opposite
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