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A Project for Flying.

In Earnest at Last!

1871

Price, TWENTY-FIVE CENTS.




A Project for Flying.


In Earnest At Last.



The following appeared in one of our public journals of the date
indicated

_To the Editor of the Tribune._

SIR:--You rightly appreciate the interest with which the popular
mind regards all efforts in the direction of navigating the air.

One man of my acquaintance was deeply interested to know the
results of the California Experiment, because he alone, as he believed,
had questioned Nature and learned from her the great secret of aerial
navigation.

To-day's _Tribune_ brings us the full account of the machine, its
performance and _modus operandi_; and without the authority of my
friend, I can pronounce at once that the thing is simply ridiculous. It is
the same old useless effort, with the same impossible agents. But to-day,
within twenty miles of Trinity steeple, lives the man who can give to
the world the secret of navigating the air, in calm or in storm, with
the wind or against it; skimming the earth, or in the highest currents,
just as he wills, with all the ease, and all the swiftness, and all the
exactitude of a bird.

My friend is only waiting for an opportunity to perfect his plan, when
he will make it known.

Yours truly,

W.H.K.

_New York; June 14th_, 1869.

Two years have passed and no progress has been made in aerial
navigation.

The California Experiment failed. The great Airship "CITY OF NEW
YORK," had previously escaped the same fate, only because more prudent
than her successor she declined a trial. The promising and ambitious
enterprise of Mr. Henson has hardly been spoken of for a quarter of a
century. And notwithstanding the fact that the number of ascensions in
balloons in the United States and Europe must be counted by thousands,
and although the exigencies of recent wars have made them useful, yet
it must be confessed that the art of navigating the air remains in
much the same state in which the brothers Montgolfiers left it at the
close of the last century.

The reason for this want of progress in the art referred to, is not to
be sought in any want of interest in the subject, or of enthusiasm in
prosecuting experiments. Certainly not for want of interest in the
subject because _to fly_, has been the great desideratum of
the race since Adam. And we find in the literature of every age
suggestions for means of achieving flight through the air, in
imitation of birds; or for the construction of ingenious machines for
aerial navigation. And if history and traditions are to be credited,
it would be equally an error to suppose that our age alone had
attempted to put theory into practice in reference to navigating the
air.

Even the fables of the ancients abound with stories about flying: that
of Dedalus and his son Icarius, will occur to every reader. And the
representations of the POETS, and the allusions in HOLY WRIT equally
prove how natural and dear to the mind of man is the idea of
possessing "wings like a dove."

But it is safe enough to assert, that hitherto, all attempts at
_navigating_ the air have been failures.

Floating through the atmosphere in a balloon, at the mercy not only of
every _wind_ but of every _breath_ of air, is in no adequate
sense aerial navigation. And I do not hesitate to say, that balloons
are absolutely incapable of being directed.

All the analogies by which inventors have been encouraged in their
expectations are false, the rudders of ships and the tails of birds
are no exceptions. They will never be able to guide balloons as
sailors do ships, by a rudder, because ships do not float suspended
in the water as balloons float in the air; nor do birds _float_
through the air in any sense. They are not bouyant--lighter than the
element in which they move, but immensely heavier; besides they do not
guide themselves wholly by their tails. We may depend upon it, if we
ever succeed in navigating the air, it will be by a strict adherence
to the principles upon which birds fly, and a close imitation of the
means which they employ to effect that object.

It is true, that in respect to the means to be employed, animals
designed by the Creator for flight, have greatly the advantage of us,
but what natural deficiencies will not human ingenuity supply, and
what obstacles will not human skill overcome? It has already triumphed
over much greater than any that Nature has interposed between man and
the pleasures of aerial communication.

We have to a great extent, mastered the mysterious elements of nature.

We have conquered the thunderbolt and learned to write with the
burning fluid out of which it is forged.

We have converted the boundless ocean into a vast highway, traversed
for our use and on our errands, by the swift agent, and by great ships
driven against wind and tide by the mighty power of steam.

And yet a single generation ago, we knew nothing of all this, Our
grand-sires would have given these achievements a prominent place in
the list of impossible things.

But, do you say, "the Creator never intended us to
fly--_therefore_, it is impossible."

For what did the Creator give us skill and boundless perseverance?
Was it designed that we should _swim_, more than that we should
furnish ourselves with wings and mount up as eagles? "We sink like
lead in the mighty waters," we only fall a little faster through the
air.

Still, I grant that the problem of aerial navigation will only be
solved when the principles of flight are clearly understood, and we
recognize precisely what are the obstacles which prevent us from
flying by artificial means.

Will these obstacles prove insuperable? It is at present believed by
the multitude that they will, but I entertain a different opinion,
most decidedly.

From my earliest youth this subject has occupied my thoughts. It
has been the study of my life, and I modestly trust that I have not
questioned nature and science in vain.

In the first place, I undertook to make myself familiar with the
obstacles to be overcome. I found the greatest of these to be gravity.
I found, however, that heavy fowls, who were unable to rise _from
the earth_, and only accomplished flight by taking advantage of an
eminence, sustained themselves without difficulty when once fairly
embarked. I also found that the best flyers were not equal to the feat
of keeping me company, when walking at my usual pace; hence I inferred
that _velocity_ was a necessary element in flight, and that
gravity, so fatal to human attempts to fly, might be made a powerful
auxiliary when rightly used.

Acting upon this hint, I made experiments with heavy barn yard fowls,
and finally constructed a light apparatus to be operated by myself,
using, principally, my feet as a motive power, which I repeatedly
tried with various and _constantly increasing_ degrees of
success.

Now I am satisfied that my system is right. It is my sober conviction
that the time to realize the dream and hope of ages has come.
Startling as the announcement may be, I propose not only to make short
excursions through the air myself, but to teach others to do the same.

Yet, knowing perfectly the obstacles in the way of flight, and knowing
equally well how to overcome them, I am yet well aware that I must
perfect my knowledge by practice before entire success can be
achieved.

This is only reasonable.

How was it with the swimmer; how was it with the agile and dexterous
skater; how with the acrobat, and what but practice has just enabled
WESTON to walk one hundred and twelve miles in twenty-four hours, and
four hundred miles in five days?

For want of a better name, I will call the machine upon which I am to
practice, the "Instructor." It is simple, but it gives the learner
just what he wants--an endless series of _inclined planes_.

It will prevent accidents, and until the student has mastered the
mechanical movements necessary to flight, will supplement his efforts
by partially balancing his weight.

It consists of a beam fifty feet long, poised and attached by a
universal joint to the top of a form post, say twenty feet or more in
height. Upon one end of this beam the practitioner stands, arrayed in
his wings. A movable weight at the other end completes the apparatus;
and yet this simple machine, will form the entering wedge to aerial
navigation.

And now methinks I see you smile, but, my unbelieving friends, let me
remind you that COPERNICUS, and GALILEO, and FRANKLIN, and FULTON,
and MORSE,--all better men than your humble servant, were laughed at
before me.

_Their_ work is done. Their monuments stand in all lands, and yet
_one_ of this band of truly great and worthy names still lives,
and to him I am indebted for many kind and encouraging words.

It is little besides this that I ask of _you_. The stock which
you are solicited to take in this enterprise is small. But enable me
by your patronage to devote myself for a time wholly to my project.
See to it, that I do not fail for want of support. Buy my little
pamphlet at its insignificant cost, ask your friends to do so; and
should any of you wish to contribute anything more to this cause,
which I have made my own, and which I am determined to push to
a triumphant issue, he may be sure that he will receive the
acknowledgments of a grateful and earnest man, who has himself devoted
to it the aspirations and efforts of a long life, and who is still
willing to take all the risks of failure upon himself.

The undersigned would be pleased to have friends interested in this
subject, call upon him, when the matter will be more fully described.

ROBERT HARDLEY,

17 PERRY STREET, or

114 Sixth Ave., cor. 9th St.


[Illustration: THE AERIAL MACHINE.]




REMARKS ON THE ELLIPSOIDAL BALLOON,

PROPELLED BY THE

_Archimedean Screw_,

DESCRIBED AS THE NEW AERIAL MACHINE,

NOW EXHIBITING AT THE ROYAL ADELAIDE GALLERY, LOWTHER ARCADE, STRAND.




REMARKS, &c.


The object proposed in the construction of the Machine which is here
presented to the public view, is simply to illustrate and establish
the fact, that, by a proper disposition of parts and the application
of a sufficient power, it is possible to effectuate the propulsion or
guidance of a Balloon through the air, and thus to prepare the way for
the more perfect accomplishment of this most interesting and desirable
result.

In the contrivance of this design, one of the first effects aimed
at was to reduce the resistance experienced by the Balloon in its
progress, which is greater or less according to the magnitude and
shape of its opposing surface. To this intent is the peculiar
_form_ of the Balloon, which is an _Ellipsoid_ or _prolate
spheroid_, the axis of which is twice its minor diameter; in
other words, twice as long as it is broad. By this construction the
opposition to the progress of the Balloon in the direction of either
end is only one _half_ of what it would be, had it been a Balloon
of the ordinary spherical form and of the same diametrical magnitude.
For the exact determination of this proportion we are more
particularly indebted to the researches of Sir George Cayley, a
distinguished patron of the art, who, a few years back, instituted a
series of experiments with a view to ascertain the comparative amounts
of resistance developed by bodies of different forms in passing
through the air; the results of which he communicated to the world in
an essay first published in the Mechanic's Magazine, and afterwards in
a separate pamphlet. According to these experiments it appears, that
the opposition which an ellipsoid or oval (of the nature of the
Balloon, if we may so call it, in the model) is calculated to
encounter in proceeding _endways_ through the atmosphere is only
_one-sixth_ of what a _plane_ or _flat_ surface of equal area with its
largest vertical section, would experience at the same rate; while the
resistance to the progress of a globe, such as the usual Balloon, would
be one third of that due to a similar circular plane of like diameter:
shewing an advantage, in respect of diminished resistance, in favour of
the former figure, to the extent we have above described; an advantage it
enjoys along with an increased capacity for containing gas--the cubical
contents of an ellipsoid of the proportions here observed, being exactly
double of those of an ordinary Balloon of equal diameter, and
consequently competent to the support of twice the weight.

Independent of the advantage of reduced resistance in this form, there
is another of nearly, if not quite, equal importance, in the facility
it affords of directing its course; an object scarcely, if at all,
attainable with a Balloon of the usual description however powerfully
invested with the means of motion; as any one will readily perceive
who has ever noticed or experienced the difficulty, or rather the
impossibility, of guiding a tub afloat in the water, compared with the
condition of a boat or other similarly constructed body, in the same
element. The efficacy of this provision and its necessity will appear
more forcibly when we observe that whenever the Balloon in the machine
here described is thrown out of its direct bearing by the shifting of
the net-work which connects it with the hoop, or by any other accident
whereby its position is altered with respect to the propelling power,
its course is immediately affected, and it ceases to progress in a
straight line, following the direction of its major axis, unless
corrected by the intervention of a sufficient rudder.

The second object, after establishing a proper form for the floating
body, was to contrive a disposition of striking surface that should
be able to realise the greatest amount of propulsive re-action, in
proportion to its magnitude and the force of its operation, which it
is possible to accomplish. To shew by what steps and in consequence of
what reasoning this point was determined as in the plan adopted, would
occupy considerably more space than the few pages we have to spare
would admit of our devoting to it. Suffice it to say that of all the
means of creating a resistance in the atmosphere capable of being
applied to the propulsion of the Balloon, the Archimedean Screw
was ascertained to be undoubtedly the best. It is true that by a
_direct_ impact or stroke upon the air, as for instance by the
action of a fan, or the wafting of any _flat_ surface at _right
angles_ to its own plane, the maximum effect is accomplished
which such a surface is capable of producing with a given power. The
mechanical difficulties, however, which attend the employment of such
a mode of operation are more than sufficient to counterbalance any
advantage in point of actual resistance which it may happen to
possess; at least in any application of it which has hitherto been
tried or proposed: so that here, as in the case of ships propelled
by steam, the _oblique_ impact obtained by the rotation of the
striking surface is found to be the most conducive to the desired
result; and of these, that arrangement which is termed the Archimedean
Screw is the most effective.

The result aimed at, being the development of the greatest amount of
re-action in the direction of the axis of revolution, it is not enough
to have determined the _general_ character of the instrument
to be employed; the proper disposition or inclination of its parts
becomes a question of the first importance. According as the
_turns_ of the screw are more or less oblique with respect to the
air they strike or the axis on which they revolve, more or less of the
resistance they generate by their rotation becomes _resolved_, as
it is technically expressed, in the direction of the intended course:
in other words, converted to the purpose in view, namely, the
propulsion of the Balloon.

Our limited space here again prevents us from entering into a detail
of the experiments by means of which the true solution of this
question has been arrived at, and the proper angle determined at which
the superficial spiral exercises the greatest amount of propulsive
force of which such an engine is capable. These experiments have been
chiefly carried on by Mr. Smith, the ingenious and successful adapter
of this instrument to the propulsion of steam vessels, for a series of
years, with the greatest care, and at a very considerable expense; and
the result of his experience gives an angle of about 67° or 68° for
the outer circumference of the screw, as that productive of the
maximum effect; a conclusion which is further verified by the
experiments of Sir George Cayley, of Mr. Charles Green, the most
celebrated of our practical aeronauts, and others who have employed
their attention upon the subject. This conclusion requires only one
modification, which ought to be noticed; namely, that in cases of
extreme velocity, the number of the angle may be still further
increased with advantage, until an inclination of about 73° be
obtained; when it appears any further advance in that direction is
attended with a loss of power. With these facts in view, the impinging
surface of the Archimedean Screw, in the model under consideration,
has been so disposed as to form, at its outer circumference, an angle
of 68° with the axis of revolution, gradually diminishing as it
approaches the centre, according to the essential character of such a
form of structure.

The novelty of the application of this instrument to the propulsion
both of ships and balloons, suggests the propriety of a few more
explanatory remarks to elucidate its nature and meet certain
objections which those who are ignorant of its peculiar qualities are
apt to raise in respect of it.

Previous to the adoption of this particular instrument, various
analogous contrivances had been resorted to in order to produce the
same effects. Of these, examples are afforded in the sails of the
windmill, the vane of the smoke jack, and of more modern introduction,
the _propellers_ designed by Mr. Taylor for the equipment of
steam-boats, and which Mr. Green has availed himself of to shew
the effect of atmospheric re-action in directing the course of the
balloon. Now all these and similar expedients are merely modifications
of the same principle, more or less perfect as they more or less
resemble the perfect screw, but all falling far short of the efficacy
of that instrument in its primitive character and construction. The
reason of this deficiency can be readily accounted for. All the
modifications alluded to, which have hitherto been applied to the
purposes of locomotion, are adaptations of _plane_ surfaces.
Now it is the character of _plane_ surfaces to present the
same angle, and consequently to impinge upon the air with the same
condition of obliquity throughout. But the _rate_ of revolution,
and consequently of impact, varies according to the distance from the
axis; being greatest at the outer edge, and gradually diminishing as
it approaches the centre of rotation, where it may be supposed to be
altogether evanescent. Now it is by the re-action of the air against
_one_ side of the impinging plane, that the progressive motion is
determined in the opposite direction, which re-action is proportioned
to the _rate_ of impact, the angle remaining the same. If then
we suppose a re-action corresponding to the _greatest rate_ of
revolution, which is that due to the _outermost_ portion of the
impinging surface (that most removed from the axis of rotation) we
shall have a _progressive_ motion in the whole apparatus greater
than the rate of impact of the _innermost_ or more central
portions of the revolving plane; and accordingly the re-action will be
thereabouts transferred from the back to the front of the propulsive
apparatus, and tend to retard instead of advancing the progress of
the machine to which it is attached. This inconvenience is felt and
acknowledged by all those who have employed this principle to obtain a
progressive motion, and accordingly a provision has been made against
it in the _removal_ or _reduction_ of the central portion
of the revolving vanes, with a view to let the air escape or pass
through as the instrument advances; a provision which is certainly
effectual to that end, but at the cost of the _surface_, which is
the ultimate source of the required re-action. All this is avoided
in the use of the perfect screw. There, the rate of rotation and the
angle of impact mutually corresponding, may be said to play into each
other's hands; the spiral becoming more extended as the impact becomes
less forcible, that is as it approaches the centre, where both
altogether vanish or disappear; thus obviating the possibility of any
interruption to the course of the machine from the contrarious impact
of the air, however quick or however slow the motions, either of the
screw itself or of the machine which is propelled by its operation. In
attestation of this fact and as showing the immunity of the perfect
screw from the disparaging effects experienced by the other modes of
accomplishing the same object, I will only mention a circumstance
related to me by Mr. Smith himself, to whom I am glad to acknowledge
myself indebted for so much valuable information respecting this
instrument, which, by the light he has thrown upon its use and the
improvements he has introduced into its construction, he may be truly
said to have made his own. Upon a late occasion, when trying one of
the larger class of vessels which had just been furnished by him upon
this principle, some persons not perceiving the true nature of the
figure employed, contended that some opposition must be experienced by
the central portion of the screw, which revolved so much less rapidly
than the rate of the ship itself. In order to convince them of their
error, Mr. Smith caused a portion of the surface in question, next the
axis, to a certain distance, to be cut away, leaving an opening, by
which, for the water to escape. The result was, immediately the loss
of one mile an hour in the rate of the ship; thus shewing that even
the most apparently feeble portion of the impinging surface of this
instrument contributes, in its degree, to the constitution of the
aggregate force of which it is productive.

This peculiarity of construction is the main cause of the advantage
which the Archimedean Screw possesses over all its types or
imitations; but it is not the only one. The _entirety_ or
_unbroken continuity_ of its surface is another, not much less
influential. The value of this will be the more readily appreciated
when we consider that air, unlike water and other non-elastic fluids,
undergoes a rarefaction or impoverishment of density, and consequently
of resisting power, accordingly as it is swept away by the rapid
passage of impinging planes; the parts immediately _behind_, and
to a considerable distance, being thereby relieved from the support
they had previously experienced, and extending (and consequently
becoming thinner) in order to fill up the space thus partially cleared
away. Now it is evident that if other planes be brought into operation
in the parts of the atmosphere thus impoverished, before they have
had time to recover their pristine or natural density, they will
of necessity act with diminished vigour; the resistance being ever
proportioned to the density of the resisting medium. This is the
condition into which, more or less, all systems of revolving planes
are necessarily brought, that consist of more than one; and is a
grand cause of the little real effect they have been made capable
of producing, whenever tried. The nature of this objection, and the
extent to which it operates, will appear most strikingly from the
following fact. Mr. Henson's scheme of flight is founded upon the
principle of an inclined plane, started from an eminence by an
extrinsic force, applied and _continued_ by the revolution
of impinging vanes, in form and number resembling the sails of a
windmill. In the experiments which were made in this gallery with
several models of this proposed construction, it was found that so far
from _aiding_ the machine in its flight, the operation of these
vanes actually _impeded_ its progress; inasmuch as it was always
found to proceed to a greater distance by the mere force of acquired
velocity (which is the only force it ever displayed), than when
the vanes were set in motion to aid it--a simple fact, which it is
unnecessary to dilate upon. It is to the agency of this cause, namely,
the broken continuity of surface, that, I have no doubt, is also to be
ascribed the failure of the attempt of Sir George Cayley to propel a
Balloon of a somewhat similar shape to the present, which he made at
the Polytechnic Institution a short while since, when he employed
a series of revolving vanes, four in number, disposed at proper
intervals around, but which were found ineffectual to move it. Had
these separate surfaces been thrown into _one_, of the nature
and form of the Archimedean Screw, there is little doubt that the
experiment would have been attended with a different result. In
accordance with the principles here illustrated, the Archimedean
Screw properly consists of only _one_ turn; more than one being
productive of no more resistance, and consequently superfluous. A
single unbroken turn of the screw, however, when the diameter is of
any magnitude, would require a considerable length of axis, which in
its adaptation to the Balloon, would be practically objectionable;
accordingly _two half turns_, nearly equivalent in power to one
whole turn, has been preferred; as in most instances it has been by
Mr. Smith, himself, in his application of it to the navigation of the
seas,

Indeed, in all other respects, except the nature of its material, the
screw here represented is exactly analogous to that used by Mr. Smith
in its most perfect form, having been, in fact, designed, and in part
constructed under his own supervision.[A]

The model upon which these principles have been now, for the first
time, successfully, at least, tried in the air, is constructed upon
the following scale. The Balloon is, as before stated, an ellipsoid
or solid oval; in length, 13 feet 6 inches, and in height, 6 feet 8
inches. It contains, accordingly, a volume of gas equal to about 320
cubic feet, which, in pure hydrogen, would enable it to support a
weight of twenty-one pounds, which is about its real power when
recently inflated, and before the gas has had time to become
deteriorated by the process of _endosmose_.[B] The whole weight
of the machine and apparatus is seventeen pounds; consequently there
is about four pounds to spare, in order to meet this contingency.

[Footnote A: The frame was made at Mr. Smith's request, by Mr.
Pilgrim, of the Archimedes; the original experimental vessel in which
this mode of propulsion was first tried upon the large scale. Mr.
Pilgrim has been long versed in all that relates to the mechanism of
this instrument, and is indeed a most expert and ingenious artist.]

[Footnote B: _Endosmose_ is that operation by which gases of
different specific gravities are enabled, or rather forced to come
together through the pores of any membranous or other flexible
covering by which it is sought to restrain them. As above referred to,
it is the introduction of atmospheric air into the body of the Balloon
through the pores of the silk, however accurately varnished, by which
the purity of the hydrogen gas is contaminated, and its buoyant power
ultimately exhausted This it is impossible to prevent by any process,
except the 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 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 of
the machine itself and of its gaseous contents. And this momentum,
which is ever proportioned to the rate of its motion, and,
consequently, to the amount of resistance it experiences, is amply
sufficient to secure the preservation of the form of its opposing
front, however partially distended, and whatever the velocity with
which it might happen to be endowed. Independently, however, of this
corrective principle, another, equally efficacious is afforded in the
buoyant power of the included gas, which, occupying all the upper part
of the Balloon so long as it is in a condition to sustain itself in
the air, and generally extending to its whole capacity, presses from
within with a force far greater than any it could experience from
the external impact of the atmosphere, and sufficiently resists any
impression from that quarter which might tend to impair its form.
To what extent this is effective, will appear more clearly when we
observe that in any balloon inflated, it is the _sides_ of the
distended globe that bear out the weight of the appended cargo,
through the intervention of the network; a weight only limited by the
sustaining power of the machine itself, and in the case of the great
Vauxhall or Nassau Balloon, amounting to more than two tons, and
consequently pressing with a force far exceeding any that could arise
from the impact of the air at any rate of motion it could ever be
expected to accomplish. And this statement, which represents the
theoretical view of the question, is fully borne out by the real
circumstances of the case as they appear in practice. So far
from justifying the apprehensions of those who conceive that the
_front_ of the Balloon would be disfigured by its compulsory
progression through the air, the result is exactly the reverse; the
only tendency to derangement of form displaying itself in the part
_behind_, where the rushing in of the atmospheric medium to fill
the place of the advancing body (in the nature of an _eddy_,
as it is termed in water), might and no doubt would, to some extent
(though perhaps but slightly) affect the figure of that part, in a
manner, however, calculated rather to aid than to impair the general
design in view,

Another error of more universal prevalency, because of a more
superficial character, regards the condition of the Balloon as
affected by the currents of air, in and through which it might have
to be propelled. The arguments founded upon such a view of the case,
generally assume some such form as the following--"It is true you can
accomplish such or such a rate of motion; but that is only in a room,
with a calm atmosphere, or with a favourable current of wind. In the
open air, with the wind at the rate of twenty or thirty miles an hour,
your feeble power would be of no avail. You could never expect to
direct your course _against_ the wind, and if you were to attempt
it and the wind were strong, you would inevitably be blown to pieces
by the force of the current." Now this argument is equally nought with
the preceding. The condition of the Balloon, as far as regards the
exercise of its propulsive powers, is precisely the same whether the
wind be strong or gentle, with it or against it. In neither case would
the Balloon experience any opposition or resistance to its progress
but what _itself_, by its _own_ independent motion, created;
and that opposition or resistance would be exactly the same in
whatever direction it might be sought to be established. The Balloon,
passively suspended in the air, without the exercise of a propulsive
power, experiences no effects whatever from the motion of the
atmosphere in which it is carried, however violent; and the
establishment of such a propulsive power could never subject it to
more than the force itself, with which it was invested. The _way_
which the Balloon so provided would make through the air would always
be the same, in whatever direction, or with whatever violence the wind
might happen to blow; and the condition of the Balloon would always be
the same that was due to its _own independent_ rate of motion,
without regard to any other circumstances whatever. If it was
furnished with the means of accomplishing a rate of motion equal to
ten miles an hour, it would experience a certain amount of atmospheric
resistance due to that rate; and this amount of resistance with
all its concomitant consequences, neither more nor less, would it
experience, whether it endeavoured to make this way _against_ a
wind blowing at the rate of 100 miles an hour, or _with_ the same
in its favour. The result, so far as regards its distance from the
place of starting, would, I grant, be very different; but at present
we are only considering the conditions of its motion through the
_air_, and these, I repeat, would be the same whatever the rate
or course of the wind; so that all speculations on this score
must resolve themselves into questions of _quantity_, not of
_quality_, in the effect sought to be accomplished: in other
words, all consideration of the rate of the wind must be left out of
the argument, except, in so far as it shall be taken to regulate the
limit which shall be assigned to the rate of the aerial machine, as
sufficient to justify its claims to the title of a successful mode of
navigating the skies.[A]

[Footnote A: The condition of a Balloon propelled by machinery is very
analogous to that of a boat in the water driven by oars or paddles.
Suppose such a boat to be rowing or paddling up a river against the
stream, if a piece of cork be thrown overboard it appears to be
carried away with the current. But this is delusive; it is the boat
_alone_ which really moves away from the cork. For if the boat be
left to its own course, both it and the cork will float down together;
and if the use of the oars or paddles be resumed, the distance
between the boat and the cork will proceed to develope itself exactly
according to the rate of the _boat_, without any regard to that
of the _stream_. If the stream be excessively rapid, the boatsmen
will appear to be exercising very great force to enable them to stem
the torrent and avoid being carried backward. Now the resistance which
they experience and all its attendant effects are only those which
they create for themselves, and which they would experience in exactly
the same degree were they to endeavour to move _at the same rate_
in calm water or with the current in their favour. If the current be
at the rate of ten miles an hour and they are just able to maintain
their place, they are proceeding at the rate of ten miles an hour, and
they experience the opposition due to that rate of motion; precisely
the same as they would experience if they sought to accomplish the
same rate of motion under any other circumstances. And if the current
were 100 miles an hour, they would suffer no more from endeavouring to
go against it, with the force just ascribed to them, than if they
were to exercise the same force in any other direction, or in a water
perfectly tranquil. Apply this reasoning to the case of a Balloon
propelled by machinery, and much of the obscurity in which it is
involved will disappear.]

With these conditions established, it will now be seen that we have
nothing to consider, in discussing the probable success of any scheme
of aerial navigation with the aid of the Balloon (so far as its mere
movements are concerned)[A] except the _actual rate of motion_
which it is competent to accomplish; whether or not it be sufficient
to meet the exigencies of the case as they may happen to be estimated.
That its capabilities in that respect, be displayed within a room, or
in a calm atmosphere, or under what may be called the most favourable
circumstances, has nothing in it to disparage or affect the general
question. Whatever it can do _there_, it can do the same in a
hurricane; and the only real question is, "whether, what it _can_
accomplish in respect of rate, is enough to answer the purpose in
view."

[Footnote A: I have said "so far as its mere movements are concerned;"
because the complete success of the scheme, how far it is an available
and satisfactory mode of transport, depends upon other conditions
besides the accomplishment of a given rate of motion--as for instance,
whether it be safe, or practicable, or consistent with a due
preservation of the _buoyancy_ of the Balloon, so as to allow of
its being employed in voyages of sufficient distance and duration,
or capable of being worked at moderate cost, or whether it leave
sufficient allowance for cargo; with many others of less striking
importance, which the practical aeronaut will readily suggest for
himself.]

The model we have been just describing is capable as we have seen, of
accomplishing a rate of about six miles an hour. Now the resistance to
the progress of a Balloon varies as the squares of the velocities or
rates of motion. Accordingly, for the same Balloon to accomplish
twice the speed, or twelve miles an hour, it would be necessary to be
provided with four times the power. Thus as the spring power employed
in the model is equal to a weight of 45 pounds, upon a barrel of four
inches in diameter, it would require one competent to raise 180 pounds
on the same sized barrel, to enable it to propel the same Balloon at
double the present rate.

But with regard to Balloons of different sizes and of the same shape,
the power required to produce the same rate of motion, would be as
the squares of their respective diameters: for the power is as the
resistance, the resistance as the surface, and the surface follows the
proportion just assigned. In order, therefore to propel a Balloon
of the same form and twice the diameter, at the same rate, it would
require a force of four times the amount.

Now to apply this to the consideration of a Balloon of superior
magnitude, let us assume one of 100 feet in length, and fifty feet in
height. The buoyant power of such a machine, or the weight it would
carry, supposing it inflated with gas of the same specific gravity,
compared with that of the model, would be as the cubes of their
respective diameters; or in, about, the ratio of 420 to one. Such a
Balloon, therefore, so inflated, would carry a weight of about 8700
pounds, or above three tons and three quarters. As, however, it would
be very expensive to inflate such a vessel with pure hydrogen gas, it
would be advisable to found our calculations upon the use of coal gas;
under which circumstances the weight it would carry would be limited
to about three tons. Deducting from this, one ton for the weight of
the Balloon itself and its necessary equipments, there would remain
two tons, or about 4500 pounds, to be devoted to the power, whatever
it might be, by which the machinery was to be moved, and the living
cargo it might have to carry. Nor let the reader be surprised at
the magnitude of the figures we are here employing, as if it were
something extraordinary or beyond the power of man to accomplish. The
dimensions and power we have here assumed is very little greater than
those of the great Vauxhall Balloon,[A] and considerably less than
some of _Montgolfières_, or Fire-balloons, which were first
employed.

[Footnote A: The height of the Vauxhall Balloon is about eighty feet,
its breadth about fifty. It contains 85000 cubic feet of gas, and
supports a weight of upwards of two tons.]

Now the resistance which such a Balloon as I have here described would
experience in its passage through the air, and consequently the power
it would require to establish that resistance compared with those
of the model, we have said would be as the _squares_ of their
respective diameters, or in, about, the ratio of only fifty-six to
one; in other words, whatever force it would take to propel the model
at any given rate, it would require just fifty-six times the power
to accomplish the same result with the large Balloon we have been
describing.

In order to ascertain precisely what this power would be in any given
instance, it only remains to find an expression for the spring power
with which we have been hitherto dealing, that shall be more generally
comprehensible.

This we shall do by a comparison with the power of steam, according to
the usual mode of estimating it; that is, reckoning a one-horse power
to be equal to the traction or draught of 32,000 lbs. through the
space of one foot in a minute. According to this scale, observing the
corresponding conditions of the spring--namely, the weight it balances
on the barrel, (answering to the force of traction) = 45 lbs., the
circumference of the barrel (answering to the space traversed) = one
foot, and the time of uncoiling for each turn, (answering to the rate
of the operation) say, three seconds and a half--we find the power of
the spring employed in the propulsion of the model, to be as nearly as
possible the forty-second part of the power of one horse; from whence
it is easy to deduce the conditions of flight assignable to the same,
and to different sized Balloons of the same shape, at any other degree
of speed. Assuming, for instance, a Balloon of 100 feet in length and
50 feet in height, and proposing a rate of motion equal to 20 miles an
hour, we have, in the first instance, the power required to propel
the model at that rate, compared with that already ascertained for a
velocity of six miles an hour, in the ratio of the _squares of the
two velocities_, as nearly ten to one; that is, ten forty-seconds,
or about one-fourth of a horse power. To apply this to the larger
Balloon, we must take the squares of their respective diameters; which
being nearly in the ratio of 56 to 1, gives an amount of 56 times
one-fourth or about 14 horses, as the sum of the power required.

From what particular source the power to be employed in the propulsion
of the Balloon should be deduced, is not indeed a question without
some difficulties and doubts in the determination. To all the moving
powers at present before the world some objections apply which
disparage their application, or altogether exclude them from our
consideration.

The power of the coiled spring is too limited to be employed upon
a larger scale. The use of the steam-engine is accompanied with a
gradual consumption of the resources of the Balloon in ballast, and
consequently in gas, the one being exactly answerable to the other,
and is therefore not calculated for voyages of long duration. Human
strength appears to be too feeble for great results, and moreover,
requires repose; which reduces the amount assignable to each man to a
fraction of its nominal value. Of electro-magnetism as yet we know
too little to enable us to pronounce upon it with certainty. Of the
remaining powers known only one is worth mentioning in connexion
with this subject, namely, the elastic force of air; and this I only
mention because it has been taken up by one whose authority in these
matters is deservedly entitled to much weight, and who entertains
great hopes of making it ultimately subservient to the purpose in
view.

But although none of these powers, in their present state, be so
perfectly adapted to the propulsion of the Balloon as to leave
nothing further to desire, yet are some of them so far applicable as,
undoubtedly, to enable us to accomplish, by their means, a very large
amount of success. A steam engine of the power required, namely, equal
to fourteen horses, could be easily constructed, far within the limits
of weight which we have at our disposal upon that account in the
Balloon under consideration, or even in one much smaller; and recent
improvements have so far reduced the amount of coal required for its
maintenance, that perhaps as long a voyage could be made by means of
it now, as would be expected or required. Even human strength, by
a certain mode of applying it, might be made effectual to the
accomplishment of a very sufficient rate of motion, say fourteen or
fifteen miles an hour, for, continuously, as long a period as the
natural strength of man, moderately taxed, could endure, and which we
may reckon at twelve hours.

It is true that neither the velocity here quoted, nor that before
assumed is so great as to enable the aeronaut to compete with some of
the modes of transit employed on the surface of the earth; as, for
instance, the railroads, where 25 miles an hour is not an unusual
speed. Yet is not the aerial machine which could command such a
rate of motion to be despised, or set aside as inferior in actual
accomplishments to what is already at our disposal; for it must not
be lost sight of, that railroads, or terrestrial roads of every
description, must ever be limited in their extent and direction, and
travelling on them, however perfectly contrived, subject to deviations
and interruptions, particularly in passing from one country to another
beyond the seas, which if taken into account, would reduce the
apparent estimate of their rates, considerably under the lowest of
those assigned to the Balloon in the previous calculation; and at all
events, by sea, much less, under the most favourable circumstances is
the ordinary rate of ships.

But, it may be observed, we are here counting upon a rate of motion as
established, which is only effectual to that extent in the absence of
contrary currents of wind. This is true; nevertheless it is no bar to
the use which might be made of the aerial conveyance so furnished, nor
any disparagement to the advantages which might be drawn from it;
for not only does the aeronaut possess the means of choosing, within
certain limits, the currents to which he may please to commit himself,
and of which, abundance of every variety is sure to be met with at
some elevation or other in the atmosphere, but, as in all general
arguments, where the conditions are equally applicable to both sides
of the question, they may be fairly left out as neutralising each
other, so, here it must not be forgotten, that the currents in
question, being altogether indeterminate, and equally to be expected
from all quarters, an equal chance exists of advantages to be derived,
as of disadvantages to be encountered from their occurrence; and that,
even without the means of making a selection, the admitted laws of
reasoning would justify us in considering the chances of the latter
to be fully counterbalanced by those of the former. It is enough, for
moderate success at least, if, possessing the power of avoiding the
bad, and of availing himself of the good, the aeronaut be furnished
with the means of making a sufficient progress for himself when the
atmosphere is such as neither to favour nor to obstruct him; and in
this condition I humbly conceive he would be placed, with even a
less rate of motion than that which we have before assigned, and
confidently reckon upon being able to accomplish.

FINIS.