A Project for Flying | Page 8

preservation of which the duration
of his career so entirely depends. These properties of the rudder it is not
possible to display in the present exhibition, owing to the confined
nature of the course which it is necessary to pursue; but they were
sufficiently tested in the preliminary experiments at Willis's Rooms,
where the space being larger, a circular motion was conferred upon the

machine by connecting it with a fixed centre round which it was thus
made to revolve, without the necessity of confining it to the one level.
The rate of motion which the Balloon thus equipped is capable of
accomplishing varies according to the circumstances of its propulsion.
When the Archimedean Screw precedes, the velocity is less than when
it is made to follow, owing to the reaction of the air in the former
instance against the car, the under surface of the balloon, and other
obstacles, by which its progress is retarded. Again, when the cord upon
which it travels is most tense and free from vibration, the rate is found
to be considerably accelerated, compared with what it is when the
contrary conditions prevail. But chiefly is its speed affected by the
proper ballasting of the machine itself, upon which, depends the
friction it encounters from the cord on which it travels. Under ordinary
circumstances it proceeds at a rate of about four miles an hour, but
when the conditions alluded to have been most favourable, it has
accomplished a velocity of not less than five; and there is no doubt that
were it altogether free from restraint, as it would be in the open air,
with a hand to guide it, its progress would be upwards of six miles an
hour.
Having now, I trust, sufficiently explained the principles exemplified in
the model here described, it may be expected that I should add a few
words regarding their reduction into practice upon a larger scale and in
the open air, with such difficulties to contend with as may be expected
to be encountered in the prosecution of such a design. In the first place,
however, it will be necessary to disabuse the public mind of some very
prevailing misconceptions with respect to the conditions of a Balloon
exposed to the action of the winds, pursuing its course under the
exercise of an inherent propulsive power. These misconceptions, which,
be it observed, are more or less equally participated in by the scientific
as by the ignorant, when devoid of that practical experience which is
the basis of all aeronautical proficiency, are of a very vague and general
character, and consequently not very easy accurately to define. In order,
therefore, to make sure of meeting all the objections and removing all
the doubts to which they are calculated to give rise, it will be advisable,
even at the risk of a little tediousness, to separate them into distinct

questions and treat them accordingly.
One of the most specious of these misconceptions regards the effects of
the resistance of the atmosphere upon the figure of the Balloon when
rapidly propelled through the air, whereby it is presumed its opposing
front will be driven in, and more or less incapacitated from performing
the part assigned to it; namely, to cleave its way with the reduced
resistance due to its proper form. To obviate, this imagined result,
various remedies have been proposed--such as, to construct that part of
the machine of more solid materials than the rest, or else (as suggested
by one of the most scientific and ingenious of those who have devoted
their attention to the theory of aerial navigation), to subject the gaseous
contents of the Balloon to such a degree of artificial condensation by
compression, as shall supply from within a force equal to that from
without; adopting, of course, materials of a stronger texture than those
at present in use, for the construction of the balloon. Now the
contingency against which it is here sought to provide, and which I
grant is a very reasonable one to anticipate, has nevertheless no real
existence in practice; at least in such a degree as to render it necessary
to have recourse to any particular expedient for its prevention. Taking it
for granted that the hypothesis in which it is involved is founded upon a
presumed analogy with a Balloon exposed to the action of the wind
while in a state of attachment to the earth, I would first observe that the
cases in question, however apparently analogous, are in reality
essentially dissimilar. In the one case (that where the Balloon is
supposed to be attached to the earth) all the motion, and consequently
all the momentum, is in the air; in the other case (where the Balloon is
supposed to be progressive), it is in the constituent particles