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The screw consists of an axis of hollow brass tube,
eighteen inches in 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 battledore, 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 aeronaut
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 direction.
This model (which, through want of time, we have necessarily described in an imperfect manner) was put in action at the Adelaide Gallery, where it accomplished a velocity of five miles per hour; although, strange to say, it excited very little interest in comparison with the previous complex machine of Mr. Henson --- so resolute is the world to despise anything which carries with it an air of simplicity. To accomplish the great desideratum of aerial navigation, it was very generally supposed that some exceedingly complicated application must be made of some unusually profound principle in dynamics. So well satisfied, however, was Mr. Mason of the ultimate success of his invention, that he determined to construct immediately, if possible, a balloon of sufficient capacity to test the question by a voyage of some extent --- the original design being to cross the British Channel, as before, in the Nassau balloon. To carry out his views, he solicited and obtained the patronage of Sir Everard Bringhurst and Mr. Osborne, two gentlemen well known for scientific acquirement, and especially for the interest they have exhibited in the progress of aerostation. The project, at the desire of Mr. Osborne, was kept a profound secret from the public --- the only persons entrusted with the design being those actually engaged in the construction of the machine, which was built (under the superintendence of Mr. Mason, Mr. Holland, Sir Everard Bringhurst, and Mr. Osborne) at the seat of the latter gentleman near Penstruthal, in Wales. Mr. Henson, accompanied by his friend Mr. Ainsworth, was admitted to a private view of the balloon, on Saturday last --- when the two gentlemen made final arrangements to be included in the adventure. We are not informed for what reason the two seamen were also included in the party --- but, in the course of a day or two, we shall put our readers in possession of the minutest particulars respecting this extraordinary voyage. The balloon is composed of silk, varnished with the liquid gum caoutchouc. It is of vast dimensions, containing more than 40,000 cubic feet of gas; but as coal gas was employed in place of the more expensive and inconvenient hydrogen, the supporting power of the machine, when fully inflated, and immediately after inflation, is not more than about 2500 pounds. The coal gas is not only much less costly, but is easily procured and managed. For its introduction into common use for purposes of aerostation, we are indebted to Mr. Charles Green. Up to his discovery, the process of inflation was not only exceedingly expensive, but uncertain. Two, and even three days, have frequently been wasted in futile attempts to procure a sufficiency of hydrogen to fill a balloon, from which it had great tendency to escape, owing to its extreme subtlety, and its affinity for the surrounding atmosphere. In a balloon sufficiently perfect to retain its contents of coal-gas unaltered, in quantity or amount, for six months, an equal quantity of hydrogen could not be maintained in equal purity for six weeks. The supporting power being estimated at 2500 pounds, and the united weights of the party amounting only to about 1200, there was left a surplus of 1300, of which again 1200 was exhausted by ballast, arranged in bags of different sizes, with their respective weights marked upon them --- by cordage, barometers, telescopes, barrels containing provision for a fortnight, water-casks, cloaks, carpet-bags, and various other indispensable matters, including a coffee-warmer, contrived for warming coffee by means of slack-lime, so as to dispense altogether with fire, if it should be judged prudent to do so. All these articles, with the exception of the ballast, and a few trifles, were suspended from the hoop overhead. The car is much smaller and lighter, in proportion, than the one appended to the model. It is formed of a light wicker, and is wonderfully strong, for so frail looking a machine. Its rim is about four feet deep. The rudder is also very much larger, in proportion, than that of the model ; and the screw is considerably smaller. The balloon is furnished besides with a grapnel, and a guide-rope ; which latter is of the most indispensable importance. A few words, in explanation, will here be necessary for such of our readers as are not conversant with the details of aerostation.
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