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LECTURE
ON
ARTIFICIAL FLIGHT
GIVEN BY REQUEST AT THE
ACADEMY OF NATURAL SCIENCES
AT
San Francisco, California, August 7th, 1876,
BY
WM. G. KRUEGER
WITH REFERENCE TO A MODEL OF HIS OWN INVENTION.
INDEX.
No. Page.
1 Introduction 1
2 History and Fable 2
3 Discovery of the Balloon 7
4 Noted Air Voyages 8
5 Absence of Danger 11
6 Charm of AErial Travel 12
7 AErial Voyages Health Promoting 15
8 Parachutes 16
9 The Kite 17
10 Balloons Impracticable 18
11 Reasons why the Problem has remained Unsolved 21
12 Fundamental Principles in Flight 23
13 Weight 24
14 Surface 26
15 Power 28
16 Flying Creatures, their Proportions, Movements 31
17 Mechanical Practicability of Flight 34
18 Flying Machines of the Present, their defects 37
19 The Practical Air Ship of the near Future 43
20 What AErostation will Accomplish 48
21 Closing Remarks 50
* * * * *
ERRATA.
Page 4, line 4, read "one from Koenigsberg," for "Koenigsberg."
Page 4, line 18, read "afterward," for "ago."
SAILING IN THE AIR.
I.--INTRODUCTION.
_Gentlemen of the Academy_:
The problem of artificial flight is of such great importance to
civilization; so interesting and fascinating, not only to the student,
but to every one; and it allows us to indulge in such a wide field for
speculation as to the great changes which will be wrought by the
practical solution of it in the social, political and commercial world,
that I must beg of you to consider only my good intentions in appearing
before you, and pardon my shortcomings as a lecturer. It is my first
attempt, and is simply undertaken to bring the subject more
understandingly before the public, that they may assist, morally, and
pecuniarily, the several inventors who are wrestling with it more or
less successfully--some rather less. If only one inventor in a hundred
should meet with flattering results, the attention bestowed upon all
will be repaid a thousand fold by that one's success.
The idea of sailing through the air in a flying machine is not new, nor
such an absurd one as is generally supposed; and it is indeed important
to investigate and lay it before the public more directly than has been
done heretofore through the medium of great, musty and long-winded
volumes. If found to seem practicable and feasible, it is for you,
gentlemen, to see that the future great State of California shall also
be ahead in this--one of the greatest and most important inventions of
the age--as she is, and has been in many other things before.
The subject has really been taken hold of in a thorough and scientific
manner only the last few years; but with such earnestness and scientific
knowledge and intelligence, not only by the foremost and principal
society for the advancement of the art--the Aeronautic Society of Great
Britain--to whom, really, the most credit must fall--but in every
civilized country; and so much has been done already to prove, not only
the possibility but the absolute certainty of an early practical
solution of the problem, that soon we will see the air traversed in all
directions, by aspiring man. Many seeming impossibilities of the
present, need only time and effort to become realities in the near
future.
II.--HISTORY AND FABLE.
In turning our thoughts to History, reaching back even into the mazy and
wonderful ages of fable, we find that from time immemorial the great
science of aerostation has occupied the minds of philosophers and
inventors. There can be little doubt that it was known and made use of
in olden times in isolated cases, but was again lost, like many other
important inventions.
We are furnished with many interesting proofs of this. Old Chinese,
Arabian and Hindu fables give some beautiful descriptions of aerial
chariots, in which wizards, princes and fairies sped over the fertile
and populous plains of their native country, disbursing good or evil,
according to their disposition, to the poor devils crawling in the dust
beneath them. The Jews had their cherubim. The Assyrians have left us
their winged bulls; the Greeks, their Sphinxes; while the Roman writers
describe how that mythical personage, Daedalus, a famous Athenian
artificer, and builder of the Cretan labyrinth, constructed wings with
which he flew across the AEgian Sea, to escape the resentment of Minos.
But his son, Icarus, undoubtedly of his strength giving out, fell into
the water and was drowned. Their nation has bequeathed to us various
bas-reliefs, illustrative of what appear well-proportioned wings.
Archytos, the great geometrician, made a wooden dove that flew like a
natural one, and the famous German astronomer, John Mueller, who died
suddenly in Rome, at the age of forty, in 1476, and whose memory was
celebrated last month in Germany, constructed an artificial eagle,
which flew out to greet the Emperor, Charles V, when he visited
Nuremberg. This Mueller was more widely known by the assumed name of
"Regiomontanus,"--the "Kingshiller"--that is, "one from Koenigsberg," a
small village in the heart of Germany; the custom of the times being for
learned men to adopt the latin name of their birthplace. He invented the
almanac, and prepared the first astronomical tables, by the aid of which
mariners, who, up to that late day could only make coasting voyages,
were enabled to trust themselves to the open sea, with some degree of
assurance; and Columbus was among the earliest to use these tables,
twenty years afterwards, on his first discovery voyage to America.
* * * * *
Another German, a young watchmaker's apprentice, constructed a flying
machine, with which he, when showing the same to his ignorant
townspeople, flew away to escape mobbing. His bones and pieces of the
machine were found some years afterward in a wild and isolated part of
the Black Forest. Towards the end of the fifteenth century Giovanni
Battista Dantes, of Perugia, flew several times over the Thrasimenian
Sea; he certainly must have been at a considerable elevation, for he
fell on a church steeple and broke a leg. Another account, particularly
noticed in history, is that of a man who flew high in the air in the
City of Rome, under the reign of Nero, but lost his life in the descent.
In "Astra Castra," we read that soon after Bacon's time, projects were
instituted to train up children in the exercise of flying with
artificial wings, and considerable progress was made; by the combined
effort of running and flying they were enabled to skim over the surface,
as it were, with incredible speed. This same Roger Bacon, an eminent
philosopher of the thirteenth century, and possessed of the very highest
genius and ability, whose ideas and knowledge, like Franklin's, were
many hundred years ahead of his age, descants, in one of his works, in
glowing language, on the practicability of constructing engines that
could navigate the air. He accomplished wonderful things in his day, and
was accused of holding communion with the devil, who was quite an
important personage in those times. His writings were interdicted, and
himself locked up to prevent closer acquaintanceship of his readers with
the aforesaid friend.
About the Confessor's time, a monk, Elmirus, in Spain, flew often, by
means of a pair of wings, many miles from high elevations. Cuperus, in
his treatise on "The Excellency of Man," contends that it is practicable
for human beings to attain the faculty of flying. He asserts that
Leonardo da Vinci, the great painter of the "Lord's Supper," and other
highly prized works of art, practiced it successfully. The reasoning of
the great John Wilkins, Lord Bishop of Chester, who died in 1672,
embodies the sentiments and principles of all these on the subject even
stronger. In his work on "Mechanical Motion," he treats expressly on
artificial flight, and conceives, in the sixth chapter, the framing of
such "volitant automata" very easy; and says that the time will come
when men will call for their wings when about to make a journey, as they
do now for their boots and spurs.
Lastly, in the "Journal de Savans," of the 12th of September, 1678, an
account is given of one Besnier, a locksmith of Sable, France, who
succeeded in flying. But as his machine was extremely primitive--the
wings consisting only of four rectangular surfaces, one at the end of
each of two poles, which passed over the shoulder of the operator, and
were worked alternately up and down--the inventor could only avail
himself of their aid in progressively raising himself from one hight to
another, until an elevated position was reached, when he could glide
through the air a long distance.
Many more cases could be cited. Some ended disastrously; others, because
of the apathy, distrust, ignorance, and superstition of the people, were
lost sight of again; while some, perhaps the most practical ones and of
which we find many indications in old writings, were never made known
for selfish reasons. Such has been the fate of this--one of the most
interesting problems--almost up to the present time. We were, perhaps,
not prepared sufficiently, to receive the great boon. We had to have the
printing press, steam, and electricity first, before we could attempt
this next great step towards a higher civilization.
III.--DISCOVERY OF THE BALLOON.
Although it is well understood now by most scientific men, that the
principles upon which ballooning rests, will scarcely form any part in
the solution of the problem of aerial navigation; yet, when, in 1782, the
brothers, Mongolfier, in France, made the first successful experiments
with small paper balloons, filled with heated air, it was thought that
the key to that wonderful art had been found; many applied themselves to
its improvement; and the next year already saw gas balloons on a much
larger scale.
The first passengers, who had the honor of being sent up into the realms
of space, were a sheep, a cock and a duck; and as their safe descent
proved highly satisfactory, the well-known French savan, Pilatre de
Rozier, tried the same experiment shortly afterwards with great success,
reaching a hight of nearly two miles. The glowing description of his
experience raised the excitement of all classes to fever heat. Numerous
day and night ascensions were made by diplomats, distinguished
naturalists, professors of note, scientific women and gymnastic
aspirants, and their journeys soon became more daring and extended to
wider fields.
IV.--NOTED AIR VOYAGES.
Blanchard, the supposed inventor of the parachute, with the American,
Dr. Jeffries, were the first to cross the channel from England to
France. M. Charles, the inventor of the gas balloon, and one of the
earliest and most enthusiastic advocates of aerostation, made extensive
voyages. Madame Thible, of Lyons, was the first of her sex who trusted
herself to the elastic element. Crosbie, who passed over the sea from
Ireland to England, came near losing his life; for, the balloon, being
struck with great force by an adverse current of air, and most of the
gas escaping, tore over the raging waters at a fearful speed, until the
courageous man was rescued, near the English coast, by a ship happening
in his way. But the view which he had enjoyed, seeing both countries at
once, was sublime beyond description, and compensated him for all the
danger. He had been at such a hight that, although the July sun melted
everything below, his ink was a lump of ice, and the quicksilver in the
instruments had sunk almost out of sight.
The battle of Fleurus, in 1794, was won by the French over the Austrians
principally through the aid of balloon reconnoitering; and similar
service was occasionally performed by the balloon in our own war. The
favorably known Italian, Count Zambeccari, who added many improvements
to this art, and created great interest in the principal countries of
Europe, made an ascension, in 1803, with two friends, at Bologna. The
three alighted in the Adriatic sea and were picked up by fishermen,
while the balloon, free from weight, rose again and was carried by the
wind to the Turkish fort Vihacz, where the commander, believing it a
present "sent from heaven," had it cut up in small pieces and divided
amongst his friends as amulets. But quite a "reverse opinion" was
generally entertained by most of the ignorant Christian country people,
when the huge monster happened to fall amongst them for the first time;
and their comparison of it to the "evil one" is excusable when we
consider the peculiar smell of the escaping gas, after their attack upon
it with pitchforks and similar agricultural implements.
Among other remarkable ascensions is that of Guy Lussac, who reached the
prodigious hight of nearly four and a half miles. This was exceeded,
though, by another scientific aeronaut, James Glaisher, in 1862, who,
with a companion, mounted the great altitude of seven miles--over 36,000
feet; but as he was insensible for some minutes after reaching the
elevation of 29,000 feet, the highest ever attained by human beings,
their calculations could only be approximated. The mercury in the
hygrometer--a delicate instrument for measuring the moisture in the
atmosphere--had fallen below the scale, while they were rising more than
1000 feet per minute. There are instances of balloons that have shot
upwards at the rate of fifty feet per second, or much over half a mile
per minute; but, generally, even twenty feet per second is a rare
occurrence. And here might be mentioned that, since the late serious
loss of several French scientists by asphyxia, or cold on their
unfortunate ascension, the problem of maintaining life in the highest
regions of the atmosphere has been solved in France. With a certain
apparatus, man could manage to live comfortably nearly ten miles above
the level of the sea, while, ordinarily, two miles is the most.
As to horizontal speed, perhaps the fastest time on record was made by
Garnerin and Snowdon, from London to Colchester, some eighty miles, in
one hour, or about 110 feet per second, almost swifter than an eagle
flies; and another balloon went from Paris across the Alps, to the
vicinity of Rome, in twenty-two hours, making over fifty miles per hour,
considering its zig-zag travel. The reason for such great speed is, that
the different air currents travel far faster in the upper regions than
below, where the velocity of the wind is seldom over twenty miles per
hour; and yet, were it not for the continually changing scenery, the
aeronaut would imagine himself stationary.
The shortest trip, perhaps, in the annals of this art, both as to hight
and distance, was made, a few years ago, by a gymnast, at Woodward's
Gardens, that most beautiful pleasure resort in this city. The little
disobliging monster went lazily, and with great difficulty, over the
fence and capsized promptly on the other side, leaving the trapeze-man
hanging, by the seat of his unmentionables, on the top of it in an
uncomfortable position, but no bones were broken.
V.--ABSENCE OF DANGER.
It is erroneous to suppose that aerial voyages are fraught with even
ordinary danger; on the contrary, travel by sea and land is far more so;
for, although thousands of assensions have been made, but very few
persons have met with accidents, in fact, a less number by far
comparatively, than by any other profession or mode of locomotion; and,
whenever such has happened, gross carelessness or ignorance was often
the cause.
During the late Franco-German war, over sixty balloons, many but
indifferently constructed, left Paris, during the siege, with some one
hundred and eighty persons and nearly three millions of letters. All
reached a point of safety.
Professor Wise, the most noted American aeronaut, has made, during the
last forty years, nearly five hundred voyages, and one in particular, in
1859, of nearly 1200 miles--perhaps the longest on record--with three
companions, from St. Louis, Mo., to New York State. This trip was made
partly in the midst of a tornado, while above Lake Erie, during which
time some twenty sailing crafts succumbed to the effects of the storm,
yet the intrepid aeronauts alighted in safety. M. Green, who was the
first to use coal gas, instead of pure hydrogen, and has also made
hundreds of successful ascensions, was carried from London to Weilburg,
in the central part of Germany, about seven hundred miles in eight
hours, without the slightest mishap. Lastly, Arban, crossed the Alps
from Marseilles to Turin, four hundred miles, in stormy weather during
the night. Mont Blanc to the left, on a level with the top of which he
was, resembled an immense block of crystal--sparkling with a thousand
fires; while the moon occasionally seemed to have borrowed the light of
the sun.
VI.--CHARM OF AERIAL TRAVEL.
Nothing can equal the beauty of an aerial voyage, that most wonderful,
easy and luxurious mode of locomotion, with its entire absence of
dizziness--this sensation being lost with the separation from earth, as
soon as the last cord, which unites us with the world below, is cut.
In rising from the ground, the feelings are absorbed in the novelty and
magnificence of the spectacle presented, while the ears are saluted with
the buzz of distant sound until the clouds are reached, when all is
still as death. The scene is sublime. Around and beneath, the clouds
roll in magnificent grandeur. They form pyramids, castles, reefs,
icebergs, ships and towers, and again dissolve into chaos. The half
obscured sun shedding his mellow light upon the picture, gives it a rich
and dazzling lustre. Reverence for the work of nature, the solemn
stillness, an admiration indescribable, all combined, seem to make a
sound of praise.
The earth, which is never lost sight of at any hight, except clouds
interfere or night sets in, seems to be concave, like the inside of a
flattish hollow globe, instead of the outside, as would naturally be
supposed. The reason for this optical delusion is, that the horizon
appears on a level with the aeronaut, while the distance downwards
remains unaltered, making the surface below appear like a valley. The
earth presents the panoramic view of an immense map, such as the
enchanted Alladdin must have enjoyed. The coloring, designating the
various products of the soil, is lively and exquisite. Variegated
grass-plats, the golden tinge of waving grain fields, the more sombre
foliage of the trees, the glossy surface of the water dazzling in the
sunbeams, with occasional white specks for sailing craft; the
innumerable villages, with tastefully decorated and tinny, toy-like
houses, the numerous roads tortuously spreading over the surface and
looking like chalk lines on a gaudy carpet, fairy-like carriages
seemingly drawn by mice and guided by liliputian little things. Such is
the beauty of this glorious earth. Yet, when mountains appear like ant
hills, and Niagara a neat little cascade in a pleasure garden--instead
of the raging grandeur, only a frothy bubble--man must be forcibly
reminded that he is but the minutest animalcule, and not of so much
importance as he presumes himself to be.
No less impressive is the scene at night. The sublime exhibition in the
vast solitude and darkness of night creates the most stupendous effect
upon the lonely aeronaut.
The earth's surface, as far as the eye can reach, absolutely teems with
the scattered fires of a watchful population, and exhibits a starry
spectacle below, that rivals in brilliancy the lustre of the firmament
above. A city looming up in the distant horizon gradually appears to
blaze like a vast conflagration. On drawing near, every street is marked
out by its particular line of fires; the forms and positions of the
theatres, squares and markets are indicated by the presence of larger
and more irregular accumulations of light, and the faint murmurs of a
busy population still actively engaged in the pursuits of pleasure or
the avocation of gain; all together combined form a picture, which, for
beauty and effect, can not be conceived.
Again, higher up, or when clouds intervene, the sky, at all times darker
when viewed from an elevation, seems almost black with the intensity of
night; while, by contrast, the stars redoubled in their lustre, shine
like sparks of the whitest silver, scattered upon the jetty dome around.
Nothing can exceed this density of night. Not a single object of
terrestrial nature can anywhere be distinguished, and an unfathomable
abyss of "darkness visible" encompasses one on every side. It seems like
cleaving the way through an interminable mass of black marble, and a
light lowered from these dizzy hights appears to absolutely melt its way
down into the frozen bosom of the surrounding inkiness. The cold is here
intense.
VII.--AERIAL VOYAGES HEALTH PROMOTING.
But while the charm of floating in the air is so fascinating these
delightful ascensions will be even more beneficial in sanitary respects.
Atmospheric pressure, exerting nearly 30,000 pounds upon a human being
of full growth, has much to do with the mechanical functions of life. At
a moderate elevation, one-tenth of this weight can be relieved, and at
greater hights, even one-third, as balloon experiments have sufficiently
proven. This pressure, then, diminishing upon the muscular system,
allows it to expand. The lungs at once become more voluminous and
breathing purer air; the freedom with which all the circulating fluids
of the system are allowed to act in the rare atmosphere, intensely
quicken the animal and mental faculties; the novelty of the voyage, and
the most sublime grandeur opening to the eye and mind of the invalid;
all assist to promote health, impart new life, inspire ideas and
invigorate soul and body.
VIII.--PARACHUTES.
This simple contrivance often forms an adjunct to balloons. Its
appearance is generally that of a huge family umbrella of revolutionary
times. It is likewise concave underneath, because such form, above all
others, condenses a column of atmosphere more rapidly and retards its
velocity in the descent immensely. The ribs are generally of whale-bone
or bamboo covered with strong domestic muslin, and a light wicker basket
is fastened some twelve feet underneath for the aeronaut, who may cut
himself loose from the balloon with perfect safety at any hight, and
descend slowly to the ground, if the parachute is strongly made and
perhaps fourteen feet across when open.
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
aerostation 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 aerial
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.
The fact in favor of mechanical flight is certainly incontrovertible
that less surface and less power is required and flight maintained the
longest, in proportion to heavier bodies.
It must be convincing, therefore, that it is possible for man to apply
the laws of flight to industrial purposes in the same manner as he has
been able, in these days, to apply all the other grand physical laws
that he has taken the trouble to study and fathom. The law of surface
and force reigns in the most absolute and exact manner over all flying
animals. It does not stop here. Nature, whose laws are general and
universal, has not created this one only for the restricted compass of
the winged animate beings. The law which sustains on the water the leaf
and the straw is the same for the gigantic Great Eastern; and the
mechanical law of the forces which drives the wheelbarrow also conducts
on its iron line the locomotive and its endless train.
XVII.--MECHANICAL PRACTICABILITY OF ARTIFICIAL FLIGHT.
Living beings have been, in every age, compared to machines, but it is
only in the present day that the bearing and justice of this comparison
are fully comprehensible. Modern engineers have created machines which
execute more difficult and various operations than animate beings are
capable of; yet it is always from nature first that man has to draw his
inspirations.
Of the different functions of animal mechanism, that of locomotion is
certainly one of the most important and interesting; and as we have
brought this art on land and water, by successfully imitating the
natural movements of walking and swimming, to quite a high state of
perfection, the next great problem, equally possible, because flight is
a natural movement, remains to be solved.