Part 2

By giving it a slight inclination, it can be made to descend, sliding-like, a long distance from the vertical point; and some of the flying machines we read of have likely been only a modified form of the parachute. The nautilus on the ocean moves on the principle of it, the pollen of plants is carried from one place to another by this mode; so the flying squirrel moves in parabolic curves from tree to tree and even crosses rivers when the nut crop fails; as also the flying tree-frog slants down long distances from high trees. This animal has a considerable expansion of skin, connecting the toes only, and which looks as if on its four legs were fastened those short, broad and light snow-shoes, known as Webfeet, used in our northern Territories in winter. It is, therefore, called a "webfoot" frog, but from which must not be inferred that it is "an Oregonian," for it is encountered so far only in Borneo.

IX.--THE KITE.

Every one is undoubtedly acquainted with the exceedingly simple mechanism--invented when boys commenced to exist--for the enjoyment of one of the most pleasant pastimes--kite flying. It is indulged in mostly during the fall, and, perhaps, a trifle more so in the rural districts than in the cities, because of the greater freedom of room which stubble fields and meadows allow.

But attention has also been given to the employment of this kind of ærostation as a means of support and conveyance; and kites have been made as much as thirty feet high, looking more like buoyant sails than boyish playthings, and exerting an immense power of waftage. Loaded wagons have been drawn over turnpikes; persons have frequently been carried up in the air by huge kites; and, in some parts of Europe, experiments have been made to signal and save shipwrecked people on dangerous coasts, proving sufficiently that the kite can be made, even in its present primitive state, to be quite useful.

In this connection it may "not be amiss" to state that the first person known to have ascended--some eighty years ago, as the "History of Kite Carriage" informs us, "was a Miss"--a young lady of some one hundred and twenty-six pounds, avoirdupois. She was seated in a chair underneath the gigantic structure which weighed nearly thirty pounds, had a surface of about sixty square feet, and rose most majestically to a hight of six hundred feet--an incontrovertible instance of the superior courage of the gentler sex over man.

The kite is maintained in the air by two opposing forces: the impelling power of the wind--lifting it by striking against it at an angle, and the restraining powers of the string--motive-force and gravitation combined; so that in the kite, above all, we possess in a crude form, the three principles requisite for artificial flight: the plain, weight and propelling force. By improving upon the kite, therefore, we will arrive at the practical solution of the problem of artificial flight.

X.--BALLOONS IMPRACTICABLE.

It is not creditable to the present age that the problem of ærial navigation has not been solved. But one of the causes has undoubtedly been the discovery of the balloon, which has retarded this science for nearly a century by misleading men's minds, and causing them to look for a solution of the problem by the aid of a machine lighter than air, and which has no analogue in nature.

Weight is one of three essential factors in flight, for a light body cannot be propelled through a heavier one. Hence all attempts at driving and guiding the balloons have signally failed. This arises from the vast extent of surface which it necessarily presents, rendering it a fair conquest to every breeze that blows, and because the power which animates it is a mere lifting power, which acts in a vertical line. The balloon, consequently, rises through the air in opposition to the law of gravity, by which all flying creatures are governed, very much as a dead bird falls downward in accordance with it. Having no hold upon the air, this cannot be employed as a fulcrum for regulating its movements, and hence the cardinal difficulty of ballooning as an art of locomotion and its uncertainty, because the air-currents cannot be regulated. A balloon starting from San Francisco might be intended for New York, but, against the desire of the passengers, alight in China or the Canibal Islands, which would be rather disagreeable.

It is simply astonishing to hear of people trying, year after year, to propel elongated or cigar-shaped balloons with a car underneath, and a screw-propeller, of course--an experiment which was tried, unsuccessfully, forty years ago. But this is generally the first conceived project of an aspirant for fame who commences to think on the subject, and soon fancies himself the happy possessor of the secret; yet what a very small amount of science is necessary to show its fallacy. In fact, all kinds of propositions for the propulsion of balloons have been advanced and experimented upon, but scarcely any improvements have been made since the first five years after its invention; proving, perhaps, more conclusively than anything else, that the practical propulsion of balloons is an impossibility.

The most remarkable idea in this respect, was undoubtedly that of Teissol. He flattered himself to be able to train geese or other birds to pull a balloon by being hitched to it, while the conductor, in a car underneath, was to direct their movements by the aid of a long pole. Although the training of birds is not so ridiculous as it may seem, yet he found that geese, if not too tough, answer the purpose of a good roast much better. And another genius, still more unique, long before balloons were invented, conceived the idea that air, like water, must have a defined limit, and that it was possible to sail on its surface like ships on the ocean. He did not state how to get up there, but lost no time in inducing the King of Portugal to forbid everyone, under penalty of death, to use said invention. So far, no one has come in conflict with that law.

Yet, although the balloon is impracticable as a means of transportation, it should by no means be discarded, for it can be made very useful for scientific and other observations, to give pleasure to thousands of people by fanciful ascensions, and not the least, to serve, as stated before, sanitary purposes, when captive and well secured. But instead of lowering and elevating it continually, as is being done at present, and which occasions danger and great loss of time and money, a contrivance should be made by which persons could safely, and without interruption, be carried up and down underneath parachutes.

XI.--REASONS WHY THE PROBLEM HAS REMAINED UNSOLVED.

The slow progress made, and the unsatisfactory state of the question, notwithstanding the large and universal share of attention bestowed upon the subject from earliest times, must be attributed to a variety of causes, the most prominent of which are--

"The great difficulty of the problem.

"The incapacity on the one hand, or theoretical tendencies on the other, of those who have devoted themselves to its elucidation.

"The lack of means of inventors generally, and the difficulty of obtaining the same to experiment and carry out their ideas even after the completion of their invention. Hence so many failures amongst this class, while men of genius in the literary or most other fields require but little pecuniary outlay to succeed.

"The stolid indifference of an unthinking community, which so often proves the deathblow to the mind of the philosophical inquirer, and whose aim is condemned and pronounced as 'visionary,' absurd and incapable of realization, instead of receiving that support and encouragement which is so necessary to success."

Flight has therefore been unusually unfortunate in its votaries. It has been cultivated on the one hand by profound thinkers, especially mathematicians, who have worked out innumerable theorems, but have never submitted them to test of experiment; and on the other by either uneducated charlatans who, despising the abstractions of science entirely, have made the most wild and ridiculous attempts at a practical solution of the problem; or inventors, who, desirous to triumph over some of the acknowledged difficulties of propulsion and navigation, but for want of organization or pecuniary support, or being unacquainted with preceding failures in the same direction, or ignorant of some one condition demanded by the peculiar nature of the experiment, but which is absolutely necessary to success, have also failed, thus causing still greater doubt in the public mind, and, consequently, less support to inventors in the same direction afterwards.

A common error prevails, that models are essential to help the inventor. The province of the model is to explain the invention to others after it has been made, and not to assist the inventor. Except in very restricted limits they have been found to be almost useless, and most of our valuable discoveries have been made and carried out without their aid. Watt's first condensing engine had a cylinder of eighteen inches diameter, or about the average size now in use. It is so with agricultural and other practical inventions and applies particularly to flying machines. Models often signally prove failures on a small scale, yet would be successful on a larger.

The problem is not an unphilosophical phantom, but a mathematically demonstrated truth, which needs only actual realization to revolutionize the world for the better. That the air is navigable can no longer be denied.

XII.--FUNDAMENTAL PRINCIPLES OF FLIGHT.

In contemplating the boundless atmosphere, we perceive it to be tenanted by a multitude of creatures of varied form and size, who move and direct themselves with marvellous ease and skill. These beings, so different in their nature, form and construction--from the proud eagle to the "blood-thirsty" mosquito--resemble one another in the possession of three important fundamental principles which constitute the power of flight. These are--weight or gravity, surface or resistance of the atmosphere against it, and force or power of projection.

The medium in which the phenomenon of flight is produced--the air--is an invisible, impalpable, comparatively imponderable fluid, and its density is nearly 800 times less than that of water. Hence a movement through it can be made far more rapidly than through its sister medium. Nevertheless, if agitated, it is capable of exerting great pressure, as the tempestuous storms, overturning fences, unroofing houses, uprooting trees, and carrying even large animals into the air, teach us. Hereon then, that is, the proper manipulation principally in creating artificial currents of air, hinges the secret of flight, because this phenomenon is reproduced in a manner identical, if a surface is moved against it, as we see in the wings of flying creatures.

XIII.--WEIGHT.

Weight is absolutely indispensible in flight, it adds momentum and assists the propelling power--with greater force comparatively in heavier bodies. A wooden cannon ball can fly only a fraction of the distance of an iron one; and an equal weight of musket balls, propelled by the same charge of powder, will not reach near so far as the cannon ball, because of its consolidation in one body; and a feather or little toy balloon can not only not be propelled, but will actually recoil if attempted. Hence, all flying animals are many hundred times heavier than air, and the heaviest are generally the best flyers, yet require the least amount of surface and force in proportion.

The sympathy existing between weight and power is very great. Weight acts in flight upon the oblique surfaces of the wings in conjunction with the power expended, and thereby husbanding the latter immensely. Thus only are the denizens of the air enabled to perform long journeys, while otherwise they could retain their position in the upper region but a very brief time, as their strength is no greater than that of other animals and would soon give out. Weight acts on flying creatures in a similar manner as we see it in the clock, where weight is the moving power, and the pendulum merely regulates its movements.

Of course, the belief of many, that birds have large air cells in their interior, that those cavities contain heated air, and that this heated air in some mysterious manner contributes to, if it does not actually produce, flight, falls to the ground upon the least reflection. No argument could be more fallacious. The bird is a heavy, compact, by no means bulky body, and that trifle of heated air, or gas, if such were the case, but is not, which possibly might help elevation, would be but dust in the scale. A small balloon of two feet diameter--a larger body than any bird--can lift only about a quarter of a pound. But, besides, many admirable flyers, such as bats, have no air cells; while many animals, never intended to fly, are provided with them. It may, therefore, be reasonably concluded that flight is in no way connected with air cells, and the best proof that can be adduced is to be found in the fact that it can be performed to perfection in their absence.

XIV.--SURFACE.

The next of the three properties necessary for flight, is the extension of the locomotive organs in winged beings--the planes. Although the wings in the different animals differ much in their form, texture, construction, number, and the matter which composes them, yet they resemble one another in the expansion and development of their surfaces, being stretched on each side of the body, and playing the part of a parachute. The animal, therefore, cannot fall like a stone, in obedience to the accelerated force of gravity, but it descends with a slow velocity; constant regular, and considerably abated.

This influence, then, exercised by the flat surface on the fall of masses, is seen in a sheet of paper of the same weight as a grain of lead, it will fall much more slowly. But if we make the paper a compact ball, and flatten the lead into a broad, thin sheet, the reverse result will be produced, and the paper reach the ground before the lead. Therefore, bodies in the air are light or heavy in proportion to their surfaces, and the heaviest may become light by an alteration of form. For successful flight, then, a just proportion of surface and weight is necessary; because, as stated, the air being elastic, its resistance is much more effectual with light bodies than heavy ones; and this proportion is such that the extent of surface is always in an inverse ratio to the weight of the winged animal.

The principle in the fall of flat surfaces is strictly applicable to the bird. Its weight, tending downwards, and being situated below the plain of suspension, keeps it well balanced, so that it cannot fall head over heels, nor rapidly. If the wings are inclined at an angle with the horizon, the bird will not descend vertically, but glide along an inclined plane with much greater swiftness, because the vertical distance remains unaltered in the same space of time. Hence their immense horizontal velocity, without comparatively any effort. This is in obedience to two forces--gravity, or weight, and resistance of surface.

XV.--POWER.

But for actual flight a third force is required--the propelling power, the necessary amount of which has greatly been overrated by many mathematicians.

Borelli estimated the power of a three pound bird to be over one hundred and thirty horses relatively. But, Navier, more reasonably, calculated a force of five horses sufficient for the flight of a pigeon. Coulomb, again, offset this "great liberality" by demonstrating that the surface to support a man must be two miles long and two hundred feet wide, with the power of a "Corliss engine" to propel such a "fifty acre ranch."

Now, facts prove that man can, without danger, descend from an high elevation under a surface of much less than fifteen feet diameter; and the force to lift himself, as will be shown hereafter, is also comparatively small. He can walk up stairs, and likewise mount upon air, which, properly manipulated, becomes sufficiently solid.

It has been demonstrated beyond a doubt, that the heaviest flying animals require the smallest amount of surface and power in proportion. The surface is less, because the resistance of the atmosphere is much greater toward one unbroken body than all the parts thereof if detached. Hence a stork, weighing eight times as much as a pigeon, needs only five square feet of surface, while the eight pigeons, with nearly one square foot each, possess together over seven square feet; and the common fly, if magnified to the size of the crane, would show a surface sixty times as large.

The heaviest flyers require the least amount of power, because weight, as stated before, itself is power, which increases in a certain ratio. Hence we find the muscular force of the smaller beings, who possess little weight, to be enormous; this is particularly so with insects, who are the strongest in creation. A stag-beetle, of which two hundred weigh only one pound, can lift fourteen ounces; crickets leap eighty times their own length, and the "lively flea" can jump through space estimated at even two hundred times the length of its body--which accounts for the difficulty of catching it. If a mouse would simply reproduce the gait of a horse, its progress would be about twenty inches per minute only, and cats would soon find themselves out of employment.

Nature has wisely established a compensation to make amends for the diminutiveness of organs by rapidity of movement, and has, consequently, furnished the animal with the necessary power to produce this rapidity.

The force necessary for lifting in all winged beings is not near so great as is generally supposed. The fall of a body, continually accelerating, is seventeen feet per second, and a very great force would be necessary indeed to offset this gravitation, if that second were allowed to expire without a counter-movement; but when that body is provided with a parachute-like arrangement, there is no such rapid fall of seventeen feet per second; and when, besides, the force is applied constantly, thereby counteracting even a fraction of the fall, the power needed to accomplish this is but a trifle; it is the principle, to use a homely phrase, that "a stitch in time saves nine." What extra strength the animal possesses has to be used in pursuit or escape, from the powerful eagle to the minutest insect; they must be prepared to exert at a given moment all the strength that nature has given to them in store.

Their strength is no greater than that of fishes or quadrupeds; all possess surplus power greatly above the need of their average use, and the strength exhibited therefore by flying creatures shows only that but a small portion of it is used for lifting and propelling purposes.

Eagles have been known to carry off small deer, lambs, hares, and even young children. Many of the fishing birds, as pelicans and herons, can likewise carry considerable loads, while the smaller birds are capable of transporting comparatively large twigs for building purposes. A swallow can traverse 1000 miles at a single journey, and the swift, the fastest of all, is known to have made nearly 180 miles an hour. The albatross, despising compass and land-mark, trusts himself boldly for weeks together to the mercy or fury of the mighty ocean; and the huge condor of the Andes, as Humboldt, Darwin, Orton, and others inform us, lifts himself to a hight where no sound is heard, and from an unseen point surveys, in solitary grandeur, the wide range of plain and mountain below. He has been seen flying over the Chimborazo, and attains, on occasions, an altitude of six miles.

XVI.--FLYING CREATURES, THEIR PROPORTIONS, MOVEMENTS.

The great common characteristic of the different winged beings are the same throughout all the modifications of detail. These are, as stated, weight, extension of surface, and the mechanical application of the propelling force; so that the animal is a gliding plane, part of which is fixed and the other moveable, and the whole being maintained in stable equilibrium by the weight of the body, placed a little below the plane of suspension.

By comparing the different species it is found, by M. de Lucy and others, that the extent of surface is in inverse ratio to the weight, the determination of this ratio being based upon certain considerations. The proof of this is overwhelming. Supposing all flying creatures of the same weight, say one pound, it is found that the:

Gnat possesses 50 Common fly 22 Bee 5 Beetle 4 Sparrow 3 Pigeon 1-2/3 Stork nearly 1 Vulture 3/4 Crane nearly 1/2

Square feet of surface per pound.

Thus we find the gnat, of which 160,000 make one pound, and which weighs four hundred and sixty times less than the beetle, has thirteen times more surface, comparatively. The sparrow weighs about ten times less than the pigeon, and has twice as much surface in proportion. The Australian crane--one of the heaviest birds, it weighs over twenty pounds, or almost three million times as much as the gnat--possesses the least surface--not quite ten square feet, or one hundred and twenty times less than that insignificant but formidable animal. Yet its flight is, gliding softly on the air, without effort or fatigue, with but little exertion, the longest maintained, and it can, with few exceptions, elevate itself the highest.

In regard to the movements of the wings, there is a similar ratio; for, while the mosquito makes over two hundred wing strokes per second, the sparrow makes only thirteen, the buzzard three, and so on, continually decreasing with heavier bodies.

A word about bats and flying fish. Although bats present no real resemblance whatever to birds or insects, but are much more like ourselves, they must be classed amongst the creatures of the air, because they are constantly moving in it, and governed by the same laws.

Their flight, being somewhat fluttering, but otherwise powerful, true and perfect, is undoubtedly caused, particularly in the early part of the night, when feeding, by their darting right and left after the almost invisible numerous insects, which they devour at once.

The wing of the bat is, like that of the bird, concavo-convex, and also more or less twisted upon itself, but it differs in so far that its arm is not covered with feathers, but a very delicate membrane, which forms the parachute-like wing.

Their nocturnal, and therefore disreputable habits, with our dislike for the blood-sucking propensity of a large specie, the vampire, has kept our interest in these otherwise harmless and clean creatures at rather freezing point. But they can be tamed easily, and are capable of giving considerable pleasure.

The flight of a shoal of flying-fish as they shoot forth from the dark green wave in a glittering throng, gleaming brightly in the sunshine, is a charming sight. But these fish can scarcely be classed with the creatures of the air, because true flight, that is the manipulation of the wings, is lacking. They are mentioned because they represent, like the kite, the first step toward that true flight which all other creatures in the air possess.

They are capable of moving through the air from 500 to 600 feet, and as much as 20 feet above the water. The fish first acquires initial velocity by a preliminary rush through the water, when it throws itself suddenly into the air, and, at the same moment, spreads out, kite-like, at a slight inclination upwards, its extraordinarily large pectoral fins. It keeps up the great speed until its momentum is exhausted, when the same performance is repeated.