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| author | Roger Frank <rfrank@pglaf.org> | 2025-10-15 04:36:22 -0700 |
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| committer | Roger Frank <rfrank@pglaf.org> | 2025-10-15 04:36:22 -0700 |
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diff --git a/11244-h/11244-h.htm b/11244-h/11244-h.htm new file mode 100644 index 0000000..1bf23d2 --- /dev/null +++ b/11244-h/11244-h.htm @@ -0,0 +1,1036 @@ +<?xml version="1.0" encoding="UTF-8" ?> +<!DOCTYPE html + PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> + +<html> + +<head> +<title>A Project for Flying, by Robert Hardley</title> + +<style type="text/css"> + <!-- + + body { + margin .5em; + font-family: Verdana, Arial, sans-serif; + } + + h1, h2 { + text-align: center; + font-weight: bold; + font-variant: small-caps + } + + .smallcaps { font-variant: small-caps } + + a { text-decoration: none; } + a:hover { background-color: #ffffcc } + + div.chapter { + margin-top: 4em; + } + + hr { + height: 1px; + width: 80%; + } + + div.note { + border-style: dashed; + border-width: 1px; + border-color: #000000; + background-color: #ccffcc; + font-size: .8em; + margin: 10px; + width: 40%; + float: right; + } + + div.note p { + margin: 10px 10px 10px 10px; + } + +--> +</style> +</head> + +<body> +<div>*** START OF THE PROJECT GUTENBERG EBOOK 11244 ***</div> + +<div class="tp"> +<h1 class="title">A Project for Flying.</h1> + +<h2>In Earnest at Last!</h2> + +<h3>1871</h3> + +<h3>Price, TWENTY-FIVE CENTS.</h3> +</div> + + +<div class="chapter"> +<h2>A Project for Flying.</h2> + + +<h3>In Earnest At Last.</h3> + + + +<p>The following appeared in one of our public journals of the date +indicated</p> + +<blockquote><p><em>To the Editor of the Tribune.</em></p> + +<p><span class="smallcaps">Sir</span>:--You rightly appreciate the interest with which the popular +mind regards all efforts in the direction of navigating the air.</p> + +<p>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.</p> + +<p>To-day's <em>Tribune</em> brings us the full account of the machine, its +performance and <em>modus operandi</em>; 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.</p> + +<p>My friend is only waiting for an opportunity to perfect his plan, when +he will make it known.</p> + +<p>Yours truly,</p> + +<p>W. H. K.</p> + +<p><em>New York; June 14th</em>, 1869.</p></blockquote> + +<p>Two years have passed and no progress has been made in aerial +navigation.</p> + +<p>The California Experiment failed. The great Airship "<span class="smallcaps">City of New +York</span>," 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.</p> + +<p>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 <em>to fly</em>, 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.</p> + +<p>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."</p> + +<p>But it is safe enough to assert, that hitherto, all attempts at +<em>navigating</em> the air have been failures.</p> + +<p>Floating through the atmosphere in a balloon, at the mercy not only of +every <em>wind</em> but of every <em>breath</em> of air, is in no adequate +sense aerial navigation. And I do not hesitate to say, that balloons +are absolutely incapable of being directed.</p> + +<p>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 <em>float</em> +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.</p> + +<p>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.</p> + +<p>We have to a great extent, mastered the mysterious elements of nature.</p> + +<p>We have conquered the thunderbolt and learned to write with the +burning fluid out of which it is forged.</p> + +<p>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.</p> + +<p>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.</p> + +<p>But, do you say, "the Creator never intended us to +fly--<em>therefore</em>, it is impossible."</p> + +<p>For what did the Creator give us skill and boundless perseverance? +Was it designed that we should <em>swim</em>, 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.</p> + +<p>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.</p> + +<p>Will these obstacles prove insuperable? It is at present believed by +the multitude that they will, but I entertain a different opinion, +most decidedly.</p> + +<p>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.</p> + +<p>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 <em>from +the earth</em>, 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 <em>velocity</em> 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.</p> + +<p>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 <em>constantly increasing</em> degrees of +success.</p> + +<p>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.</p> + +<p>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.</p> + +<p>This is only reasonable.</p> + +<p>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?</p> + +<p>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 <em>inclined planes</em>.</p> + +<p>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.</p> + +<p>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.</p> + +<p>And now methinks I see you smile, but, my unbelieving friends, let me +remind you that <span class="smallcaps">Copernicus</span>, and <span class="smallcaps">Galileo</span>, and <span class="smallcaps">Franklink</span>, and <span class="smallcaps">Fulton</span>, +and <span class="smallcaps">Morse</span>,--all better men than your humble servant, were laughed at +before me.</p> + +<p><em>Their</em> work is done. Their monuments stand in all lands, and yet +<em>one</em> of this band of truly great and worthy names still lives, +and to him I am indebted for many kind and encouraging words.</p> + +<p>It is little besides this that I ask of <em>you</em>. 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.</p> + +<p>The undersigned would be pleased to have friends interested in this +subject, call upon him, when the matter will be more fully described.</p> + +<p>ROBERT HARDLEY,<br /> + +17 PERRY STREET, or<br /> + +114 Sixth Ave., cor. 9th St.</p> + + +[Illustration: THE AERIAL MACHINE.] +</div> + + +<div class="chapter"> +<h2>Remarks on the Ellipsoidal Balloon,<br /> +Propelled by the<br /> +<em style="font-variant: normal">Archimedean Screw</em>,<br /> +Described as the New Aerial Machine,<br /> +Now Exhibiting at the Royal Adelaide Gallery, Lowther Arcade, Strand.</h2> + + + + +<h3>Remarks, &c.</h3> + + +<p>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.</p> + +<p>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 +<em>form</em> of the Balloon, which is an <em>Ellipsoid</em> or <em>prolate +spheroid</em>, 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 <em>half</em> 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 <em>endways</em> through the atmosphere is only +<em>one-sixth</em> of what a <em>plane</em> or <em>flat</em> 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.</p> + +<p>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.</p> + +<p>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 +<em>direct</em> impact or stroke upon the air, as for instance by the +action of a fan, or the wafting of any <em>flat</em> surface at <em>right +angles</em> 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 <em>oblique</em> 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.</p> + +<p>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 <em>general</em> 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 +<em>turns</em> 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 <em>resolved</em>, 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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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 <em>propellers</em> 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 <em>plane</em> surfaces. +Now it is the character of <em>plane</em> surfaces to present the +same angle, and consequently to impinge upon the air with the same +condition of obliquity throughout. But the <em>rate</em> 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 +<em>one</em> side of the impinging plane, that the progressive motion is +determined in the opposite direction, which re-action is proportioned +to the <em>rate</em> of impact, the angle remaining the same. If then +we suppose a re-action corresponding to the <em>greatest rate</em> of +revolution, which is that due to the <em>outermost</em> portion of the +impinging surface (that most removed from the axis of rotation) we +shall have a <em>progressive</em> motion in the whole apparatus greater +than the rate of impact of the <em>innermost</em> 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 <em>removal</em> or <em>reduction</em> 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 <em>surface</em>, 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.</p> + +<p>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 <em>entirety</em> or +<em>unbroken continuity</em> 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 <em>behind</em>, 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 <em>continued</em> 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 <em>aiding</em> the machine in its flight, the operation of these +vanes actually <em>impeded</em> 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 <em>one</em>, 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 <em>one</em> 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 <em>two half turns</em>, 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,</p> + +<p>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 href="#fna">A</a>]</p> + +<p>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 <em>endosmose</em>.[<a href="#fnb">B</a>] 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.</p> + +<div class="note"><p id="fna">[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.]</p> + +<p id="fnb">[Footnote B: <em>Endosmose</em> 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 <em>metallic</em> covering; as for +instance, by <em>gilding</em> the Balloon, which would be effectual +could it be contrived to endure the constant friction and bending of +the material itself.]</p></div> + +<p>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.</p> + +<p>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 +<em>flat</em>, 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.</p> + +<p>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 <em>ballasting</em> 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.</p> + +<p>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.</p> + +<p>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 <em>motion</em>, and consequently all the +<em>momentum</em>, 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 <em>sides</em> 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 +<em>front</em> 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 +<em>behind</em>, where the rushing in of the atmospheric medium to fill +the place of the advancing body (in the nature of an <em>eddy</em>, +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,</p> + +<p>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 <em>against</em> 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 <em>itself</em>, by its <em>own</em> 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 <em>way</em> +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 <em>own independent</em> 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 <em>against</em> a +wind blowing at the rate of 100 miles an hour, or <em>with</em> 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 +<em>air</em>, 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 <em>quantity</em>, not of +<em>quality</em>, 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]</p> + +<p>[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 +<em>alone</em> 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 <em>boat</em>, without any regard to that +of the <em>stream</em>. 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 <em>at the same rate</em> +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.]</p> + +<p>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 <em>actual rate of motion</em> +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 <em>there</em>, it can do the same in a +hurricane; and the only real question is, "whether, what it <em>can</em> +accomplish in respect of rate, is enough to answer the purpose in +view."</p> + +<p>[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 <em>buoyancy</em> 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.]</p> + +<p>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.</p> + +<p>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.</p> + +<p>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 <em>Montgolfières</em>, or Fire-balloons, which were first +employed.</p> + +<p>[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.]</p> + +<p>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 <em>squares</em> 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.</p> + +<p>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.</p> + +<p>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 <em>squares of the +two velocities</em>, 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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<h4>FINIS.</h4> +</div> + +<div>*** END OF THE PROJECT GUTENBERG EBOOK 11244 ***</div> +</body> +</html> |